CA2426243A1 - Vehicle light bar antennas - Google Patents
Vehicle light bar antennas Download PDFInfo
- Publication number
- CA2426243A1 CA2426243A1 CA 2426243 CA2426243A CA2426243A1 CA 2426243 A1 CA2426243 A1 CA 2426243A1 CA 2426243 CA2426243 CA 2426243 CA 2426243 A CA2426243 A CA 2426243A CA 2426243 A1 CA2426243 A1 CA 2426243A1
- Authority
- CA
- Canada
- Prior art keywords
- antenna
- light bar
- housing
- antennas
- plastic
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Abstract
An arrangement and method for incorporating one or more communications antennas in the light bar of an emergency vehicle. The antennas can be totally within the light bar or partially within and extending out from the light bar. The antennas can be incorporated in light bars having either metal or plastic covers or tops. Various ground planes such as the light bar metal top, the track within the light bar or a metal strap secured to the top of a plastic light bar cover can be utilized. Both capacitive and direct feed methods for the antennas cam be employed and at any frequency.
Known filtering arrangements are provided to accommodate the various communication bands involved.
Known filtering arrangements are provided to accommodate the various communication bands involved.
Description
VEHTCF.,E LIGHT BAR ANTENNAS
Applicant. hereby claims priority based on United States Provis~_onal Patent Application No. 6U/374,071 filed April 1f3, 2002 and entitled "vehicle Fight Bar Antennas" which is incorporated herein by reeference.
Background Of The Invention This znvc_ntion relates to the art of vehicle antennas, and more particularly to a new and improved arrangement and method for ~.ncorporating on~~ or more l0 antennas into a vehicle l:i-ght bar.
Signal lights for emergency vehicles such as police cars, fzre trucks, ambulances, tow trucks and the like have progressed from simple dome lights to elaborate light bars which include a variety of types of signals and special purpose lights. An example of a light bar is found in United States Patent No. 6,081.,191 issued June 27, 2000 the disclosure of which is incorporated by reference.
Such emergency vehicles have need for one or more antenna depending upon the nature of the communication requirements, i.e. UHF, VHF, cellular etc. Attaching such antenna: to the body of the vehicle by means of mounting holes and the like can adversely affect the surface appe<~rance of the vehicle thereby potentially reducing its resale value.
Accordingly, it would be advantageous to incorporate the one or more communication antennas requixed by the vehicle in the light bar s~~ that no additional holes or other surface damage are made in the body of the vehicle. An important consideration in accomplishing the foregoing is optimizing the performance of the antenna in i.ts location.
Summary Of The Invention The invention provides an arrangement and method far incoz~porating one ox more communications antennas in the light bar of an emergency~vehicle. The antennas can be totally within the light bar or partially within and extending out from the light bar. The antennae can be 1o incox-porated in light bars having either metal or plastic covers or tops. various ground planes such as the light bar metal top, the track within the light bar or a metal scrip secured to the top of a plastic light bax cover can be utilized. Both capacitive and direct feed methods for the antennas can be employed and at any frequency_ Known filtering arrangements are provided to accommodate the various communication bands involved.
The following detailed description, when read in eon~u.nction with the accompanying drawing, is in such full, clear, concise and exact terms as to enable any persor~ skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the invention.
Brief Description Of The Drawings Fig. 2. is a diagrammatic perspective view of a vehicle provided with a light bar antenna according to one embodiment of the invention;
Fig. 2 is an enlarged diagrammatic perspective view of the light bar antenna of Fig. l;
Applicant. hereby claims priority based on United States Provis~_onal Patent Application No. 6U/374,071 filed April 1f3, 2002 and entitled "vehicle Fight Bar Antennas" which is incorporated herein by reeference.
Background Of The Invention This znvc_ntion relates to the art of vehicle antennas, and more particularly to a new and improved arrangement and method for ~.ncorporating on~~ or more l0 antennas into a vehicle l:i-ght bar.
Signal lights for emergency vehicles such as police cars, fzre trucks, ambulances, tow trucks and the like have progressed from simple dome lights to elaborate light bars which include a variety of types of signals and special purpose lights. An example of a light bar is found in United States Patent No. 6,081.,191 issued June 27, 2000 the disclosure of which is incorporated by reference.
Such emergency vehicles have need for one or more antenna depending upon the nature of the communication requirements, i.e. UHF, VHF, cellular etc. Attaching such antenna: to the body of the vehicle by means of mounting holes and the like can adversely affect the surface appe<~rance of the vehicle thereby potentially reducing its resale value.
Accordingly, it would be advantageous to incorporate the one or more communication antennas requixed by the vehicle in the light bar s~~ that no additional holes or other surface damage are made in the body of the vehicle. An important consideration in accomplishing the foregoing is optimizing the performance of the antenna in i.ts location.
Summary Of The Invention The invention provides an arrangement and method far incoz~porating one ox more communications antennas in the light bar of an emergency~vehicle. The antennas can be totally within the light bar or partially within and extending out from the light bar. The antennae can be 1o incox-porated in light bars having either metal or plastic covers or tops. various ground planes such as the light bar metal top, the track within the light bar or a metal scrip secured to the top of a plastic light bax cover can be utilized. Both capacitive and direct feed methods for the antennas can be employed and at any frequency_ Known filtering arrangements are provided to accommodate the various communication bands involved.
The following detailed description, when read in eon~u.nction with the accompanying drawing, is in such full, clear, concise and exact terms as to enable any persor~ skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the invention.
Brief Description Of The Drawings Fig. 2. is a diagrammatic perspective view of a vehicle provided with a light bar antenna according to one embodiment of the invention;
Fig. 2 is an enlarged diagrammatic perspective view of the light bar antenna of Fig. l;
fig_ 3 is an enlarged diagrammatic pE~rspective view, with pax~ts removed, Further illustrating the light bar antenna of Fig. 2;
Fig. 4 is a diagrammatic view of a vEhicle provided with a light. bar antenna according to another embodiment of the invention;
Fig. 5 is an enlarged diagrammatic perspective view of the light: bar antenna of Fig_ ~;
Fig. 6 is an enlarged diagrammatic pE:rspective 1o view, with parts removed, further illustrating the light bar antenna of Fig. 5;
Fig_ '7 is a perspective view illustrating a light bar antenna according to another embodimer~t of the invention wherein the light bar metal covE~r is used as the ground plane;
Fig_ 8A is a perspective view illustrating a light bar antenna according to another embodiment of the invention wherein a ground plane is provided under the plastic light bar cover;
2o Fig_ 8F3 is a perspective view, partl~~ diagrammatic and with parts removed, further illustrating the arrangement of Fig. 8A;
Fig_ 8C is an enlarged elevational v~_ew of a portion of F?ig_ 8B;
Fig. 8D is a fragmentary developed view further illustrating the antenna of Fig. 8A;
Fig. 4 is a diagrammatic view of a vEhicle provided with a light. bar antenna according to another embodiment of the invention;
Fig. 5 is an enlarged diagrammatic perspective view of the light: bar antenna of Fig_ ~;
Fig. 6 is an enlarged diagrammatic pE:rspective 1o view, with parts removed, further illustrating the light bar antenna of Fig. 5;
Fig_ '7 is a perspective view illustrating a light bar antenna according to another embodimer~t of the invention wherein the light bar metal covE~r is used as the ground plane;
Fig_ 8A is a perspective view illustrating a light bar antenna according to another embodiment of the invention wherein a ground plane is provided under the plastic light bar cover;
2o Fig_ 8F3 is a perspective view, partl~~ diagrammatic and with parts removed, further illustrating the arrangement of Fig. 8A;
Fig_ 8C is an enlarged elevational v~_ew of a portion of F?ig_ 8B;
Fig. 8D is a fragmentary developed view further illustrating the antenna of Fig. 8A;
Fig. 9A is a perspective view of a light bar antenna according to another embodiment of the invention wherein the _bight bar bottom track is used as the ground plane;
Fig. 9B is a developed view further i-Llustrating the antenna of Fig. 9A;
Fig. 9C is a developed view further i:~lustrating a portion of the antenna of Fig. 9B;
Fig. 10 is a side elevational view of a light bar antenna arx-angement according to the invention wherein different types of antennas are incorporated in the light bar;
Fig_ 11 is a fragmentary plan view showing a capacitively fed ground plane for use in the antenna of the invention;
Fig. 12A and 128 are side elevational and developed views, respectively, of an antenna of the inventa.on wherein a light bax- metal cover is used as a ground plane;
Fig. 13 is a diagrammatic fragmentary side elevational view, partly in section, illustrating capacitive «nd direct antenna Eeeds, respectively, through the plastic light bar cover in accordance with the invention;
Fig. 1~A is a perspective view of a light bar antenna according to another embodiment of: the invention;
Fig. 1413 is a developed view Further :illustrating the antenna c~f Fig . 14A;
Fig. 14c~ is a developed view further :illustrating a portion of the antenna of Fig. 14B;
Fig. 15 i.s a schematic diagram of a tt~st set up for use on an antenna of the invention;
Fig. 16 is a swept gain plot showing :cesults of a teat performed with the set up of Fig_ 15;
Fig. 17 is an arrangement of data from the test set up of Fig. 15;
Figs. 18 - 22 are pattern plots showiz~g the directivity of the antenna used in the test set up of Fig. 15;
Fig. 23 is a graph further illustrating the data from the test set up of Fig_ 15;
Fig. 24 is a pattern plot illustrating UHF data from one form of light bar antenna of the invention; and Fig. 25 is a pattern plot illustrating UHF data from a light bar of the invention employing e~cternal capacitive feed.
Detailed Description Of The Invention In accordance with the invention, one or more communications antennas are incorporated in the light bar of an em~exgency vehic~.e such as a police car, fire truck, ambulance or tow truck. One advantage of the invention is that_,incorporating the antennas) in the light bar avoids providing additional mounting holes or similar defects in tYie vehicle body which could otherwise adversely affect the body surface and ultimately th.e vehicle resale value. Another advantage is that the a.ntenna(s) is located in the best place for optimum performance on the vehicle. Fender locations can cause nulls in the antenna radiation pattern. A
further advantage is that the location also eliminates the possibility of injury to persons walking near the 1o vehicle whicx~ otherwise is possible with fEnder or trunk mount styles. Still another advantage is that this antenna location will reduce the number of antenna replacements due to breakage in car washes and other extreme environments. A further advantage is that this antenna system provides a much more effect.i.ve use of vehicle ground place :surface area.
Referring now to Fig. 1, there is shown an emergency vehicle l0, such as a police car, provided with a light bar 12 on the roof 14 thereof. The 2_0 enlarged view of Fig. 2 shows the light bar- plastic cover 16 and two communications antennas incorporated within the l:~ght bar in accordance with the: invention_ Tn this embodiment of the invention, :3hown in further deta:~.l in fig. 3, each antenna radiating element is totally contained inside the light bar, i.e. totally within the p:Lastic cover 16. Fig_ 3 shows two short quarter wave antennas 20 and 22. Each '/ wave antenna 20 and 22 is a cop loaded folded monopole that= uses the light bar track 24 as a ground plane. Eaclz antenna is fed by a coaxial cable (not shown in Fig. :3) that is transitioned to coplanar wave-guide or a c.i.rcuit board, i.e. the circuit boards 26 and 28 for antennas 20 and 22, respectively, which feeds the antenna. Low pass, high pass and/or band pass filtering is provided, as needed, for i;~olation. The number of antennas and the arrangements for feeding the antennas shown and described in Figs_ 2 and 3 are merely illustrative, and fewer or greater numbers of antennas and alternative feeding arrangements can be employed.
Referring now to Fig. 4 there is shown another l0 vehicle 40, such as a police car, px-ovided with a light bar 42 on the root 44 thereof. The enlarged view of Fig. 5 shows the light bar plastic cover 46 and three communications antennas 48, 50 and 52 incorporated in the light bar in accordance with the present invention.
In this embodiment of the present invention, shown in further deaail in Fig. 6, each antenna 48, 50 and 52 is partially within and extends fxom the light baz~.
Each antenna uses a ground plane inszde the light bar cover 46. It: is mounted just below the top of the plastic cove- 46 above the light bar cornpor~ents. In particular, t:he brass sheets 54 and 56 are the ground planes for the antenz~as 50 and 52, respectively.
Another similar brass sheet (not shown in Fig. 6) serves as the ground plane for antenna 48. As shown in Fig. 6, the base of e=ach antenna is mounted to the brass sheet ground plane, and the whip of each antenna extends out through an o~~ening provided in plastic cov<sr 46. The antenna whips can be made with nickel titanium wire to resist bending, and they will spring back t=o a vertical.
position after being flexed.
The foregoing ground plane arrangement isolate:
each antenna 48, 50 and 52 preventing the light bar components from affec_aing t:he directiv:ity of the antenna. This is believed to provide improved performance over antennas using the light bar track 60 as the ground plane. Each antenna 48, 50 amd 52 is fed directrly by ~~ coaxial cable (not shown in Fig_ 6). Low pass, high pGiss and/or band pass filtering is provided, as needed foe: isolation. The number of antennas can be fewer or gx'eater than that shown in Figs. ~E-6 and alternative arrangements for feeding the antennas can be employed_ The light bars shown in Figs. 1-6 are of the type having plastic tops. There are also vehicle light bars of the type having metal tope. Fig. 7 shows an antenna 70 according to the present invention inco:cporated in a light bar having a metal top 72 which is u~~ed as the antenna ground plane_ The antenna base 74 is mounted to the light bar metal top 72 and the anteruia whip 76 extends outwardly therefrom. This type is similar to a NMO mount, and the antenna whip length typically will be a quarter wavelength. While only one antenna is shown, more than one can be provided, each being fed by a coaxial cable such as that designated 78 in Fig. 7. Low pass, high pass and/or band pass filtering is provided, as needed, for isolation.
Fig_ 8 shows in further detail an arrangement according to the invention wherein one or more antennas are incorporated in a light bar having a plastic cover and ground ~~lane is provided under the plastic cover.
The metal gx-ound plane is designated 80 ire Fig. B with -~ 9 -antenna 82 beaing mount=ed thereto. The light bar plastic cover is des:i.gnated 84. The overall length of ground plane 80 is J~/2 with the antenna 82 being located at the a/4 mid-po~.nt~ between the ends. The antenna 82 ~.s ~/4 in length. The width dimension of ground plane 80 will_ be constrained by the width of the light bar, but the width of ground plane 80 should be made as large as possible_ Antenna 82 is fed by a capaciti~~re feed 86 and a coax 88, and the coax should pass under nhe ~/4 length section of the ground plane 80 to prevent ~,urrents on the outer surface of the coax from adverse:Ly affecting the antenna ~~peration. The capacitive feed through the plastic dome or cover 8g leaves the light bar integrity intact and protects the internal components from exposure to and damage from water, road salt and the like. This antenna arrangement for operation at and above UHF frequencies demonstrated a good ;Pattern with no bandwidth issues. More than one antenna can be Included in the arrangement, each being fed by a coax as shown, and low pass, hicgh pass and/or band pass filtering is provided, as needed, for isolation.
Fig. 8C shows in further detail the capacit~.ve feed 86 including a capacitive plate 90 and a Mylar cover 92, the covet- being shown in spaced relation from plate 90 for illustra.ta.ons, ~.?~ being understood that cover 92 is secured over' plate 90 after fznal assembly. Fig. 8D
shows the components of one illustrative .dorm of thf~
antenna 82 i.nclud~.ng an end cap 9~ and nut 95, a shrink down component 96, a memory wi,xe 97, an exaernal nut 98, base plate ~~9, screw loo and tape 10~..
For operation at. and below V'HF frequencies, due to the size of the ground plane needed for V~IF~, it is believed that use o~ the light bar track far the ground plane is the best choice. If the light baz~ track is mounted to the roof of a vehicle in a mannE:r such that the track is electrically connected to the roof and hence the body of the vehicle, the light bar track ground plane may be suitable for low band operation.
Such an arrangement i.s shown in Fig. 9 whei:e a light bar 13.o comprise~~ a cover or housing 122 and a light bar track 7.14_ ~~ capacitively-fed antenna 116 uses the light bar bottom txar_k 1.14 as the ground plane. Rs shown in Fig. 9$, antenna x_16 comprises a mast assembly 118 supported by a base assembly 120 mounted on the light bar corer or top 112. A spring base assembly 122 is located between antenna base assembly 1:20 and bottom track 114. :Fig. 9C shows the spring base ,assembly 122 in detail in~=luding a base 124 which is se,~ured to bottom track 114 by screws 125, a Teflon insulator 126, a first coil 127, a second coil 128, a contact pin 129 and a coil housing 130_ A coaxial cable (not shown) ~.s provided for feeding the antenna. This arrangement provides easy transition to coax, easy addition of filters and easy mounting to the light bar track.
Additional antennas can be included in the arrangement.
Low pass, high pass and/or band pass filtering is provided, a~ needed, fox isolation.
Fig. 1Cs il~.ustrates an arrangement according to the invention wherein different antenna stylew can be employed iri a single light bar 140. The v~iF antenna i4a on the left-hand side of_ the arrangement shown in Fig.
l0 utilizes the la,ght bar track 144 as. them ground plane _ 11 in a manner similar t« that illustrated in l~ig. 9. A
bobbin 146 as seen in Fig. ~.0 is included f«r providing a base ~.oadin~~ connection to the VHF antenna as in the arrangement of_ Fzg. 9. The UHF antenna 148 on the right:-hand side of the arrangement shown in Fig. 10 utilizes a UHF ground plane 150 added to the light bar plastic cover 152 in a manner similar to that il3ustrated in Fig. 8. This is illustrated in further detail in Fig. 11 which shows the UHF ground plane 150 added to the plastic cover 132, the UHF feed point 154 for the antenna and the coaxial cable 156 connection thereto for feeding the antenna, and the Mylar cover 158 for proteetirag the capacitive antenna feed_ Fig. 12 provides a detailed showing of haw a light bar metal cover antenna is assembled_ Antenna 170 is mounted on ttae light bar metal top 172 which serves as the ground plane arid a coaxial cable 174 i:c connected to the antenna. Components of antenna x.'70 ex.t:ernal to the light bar corer or housing are the outer end cap 176, mast 178, nut 180, Delr~.n washer 182, external. nut 184 and center conductor 186. Components of antenna 170 internal to 'the light bar covet or housing are a pair of washers 188 and 190, a ground sleeve 192 and an insulator 194.
Fig. 13 illustrates capacitive and direct antenna feeds according to the invention through the plastic light bar cover. A pair o~ antennas 200 and 202 are located on the exterior of a plastic light bar cover 204 and axe Eed by coaxial cables 20& and 208, respectively located within cover 20g. Antenna 200 illustrates the Capacitive feed method according to the ir_vention and antenna 202 illustrates the direct fieed method according to the invention. llntenna 200 includes a whip 210 (a portion of the length being shown) extending ~rom a base structure 212 which is mounted on the cover 204. A pair of metal, i.e. brass, plates 214 and 216 on. opposite surfaces of cover 204 function as the capacitor plates and the plast-is light bar cover 204 furt.ctions as the capacitor dielectric. The center conduetox~ 220 of cable 206 is connecaed to plate 214, and antenna whip 210 is connected elE~ctrically to plate 216.
Antenna 202 illustrates the direct feE.d method according to the present invention and ineJ.udes a whip 224 (a portion of the length being shown) extending from a base structure 226 which is mounted on the cover 204.
The center conductor 230 of cable 208 is connected to one end of a connector element 232 which i:~ threaded through an opening provided in cover 204 and which has the other end thereof connected electrical:Ly to whip 224_ 'rhe direct feed method also can be employed when cover 204 is of metal- in which case connecLer element 232 would be insulated from cover 204.
Both the capacitive and direct feed m~athods according to the invention can be used for any frequency. Both methods also can be employed when the light bar track is used as the ground plane as well- as in situations where the ground plane is located just below the light bar plastic cover.
Fig. 14 shows an arrangement similar to that of Fig. 9 but with components added to the ante~zna to increase versatility. In particular, a spring assembly may be incorporated into the external antenna whip to absorb lateral forces and prevent breakage.
Fuz~thex-more, an e~cternal loading coil may be added to reduce the length of the VHF antenna thereby decreasing the moment arm and reducing the chance for breakage_ Referring first to Fig. 14A, there is shown. a light bar cover or housing 240 which in this example is of plastic, and an antenna mast 242 extending out from housing 240. A loading coil 244 is connected at one axial. end to the antenna nut 246, and coil 244 is connected at the other end to one axial end of a spring assembly 248,. The other end of spring assE~mbly 248 is joined to a base component 250, as shown in Fig. 14B. A
pair of plate's 252, 254 is provided on opposite surfaces of plastic cover 240 to establish a capacit:ive feed in the manner previously described. The arrangement also includes a spring base assembly 260 within cover 240 like the arrangement of Fig. 9. As shown :en Fig. 14C, spring base ,assembly 260 ir~cludes a base W>2 secured to bottom track 264 by screws 266, a Teflon insulator 268, a fix-st coil 270, a second coil 272, a contact pin 274 and a coil housing 2'76.
The invention is illustrated further by the following information obtained from an azimuth pattern z5 and swept gain comparison test conducted vn a light bax-VHF antenna unit. The test set up is shown in F'ig. 15 and she antenna used in the test was a capacitive loaded folded mono>ole for VHF was fitted inside a light bar.
The light bar plastic cover was attached to a track. A
bobbin was mounted at one end to a circuit:. board-planar waveguide combination. which, in turn, was mounted to the track..' The: other end of the bobbin was caupled~:
_ ~L~ _ electrically to the antenna for a base loading connection. The track served a9 the antenna ground plane.
One of the objecti~res of the test is to determine haw the antenna W 11 perform when installed in a light bar. Gain arid directivity of the antennas performance need to be cr~aractex~i zed to show haw the ar~tenna W 11 perform. Then the results are compared to a 1/ wave antenna refex-ence that ie widely used by tree police l0 where the pez~formance is known.
The fol~Lowing equipment was used in the test:
Hewlett Pack<3rd 8753ES network analyzer wil:h an N
calibration lcit, two coaxial test cable as;~emblies, one 20 foot, one 120 foot, each using LMR 300 ~~oax terminated with N connectors. As shown in Fig. 15, the light bar with the V~IF unit installed and ,designated 280 in Fig. Z5 was mounted an a ~0" diameter ground plane that rotated. A log periodic dipole array 282 was set up at 100 feet from the light bax on the ground plane.
The view of the two antennas is unobstructed and the Iog periodic dipole array pointed at the ground plane. The network analyzer was set up near the ground plane. The 20-foot cable was attached in between the VHF unit and the analyzer. Then the 120-foot cable was attached in between the log periodic dipole array and the analyzer.
The analyzexv was then set up for a transmission measurement with markers set up at lSo thZ-ough 170 MHz with SMHz spacing. Marker values were recorded in dB
beginning at: 0 degrees and every 20 degz~ee~s following.
3o When this p<>rtion of the teat was completcad the light bar was removed from the ground plane. Then in the ~.
i center of the ground plane a ,~ wave antenna was installed. This antenna is the reference that the light bar antenna will be compared to. Marker data was taken of this antenna from only one direction. Being mounted in the center of: a round ground plane th~~ antenna will give equal results from any direction. 'hhe results were entered in a excel spreadsheet and plotted. The network analyzer w<~s then set up for a SWR measu:cement of the VHF unit. A standax-d calibration was pe:cformed.
to The swept gain plot of Fig. 7.6 is the result of a transmission measurement from the anaLyzc:r. The data for the raw data crzarts of Fig. 17 comes from thin measurement. The swept gain measurement shows a drop in amplitude at 157 M~~z. At this weak point: the s~.gnal to noise levea_ ~.s h~.gta creating extra error for the 155 MHz plot. Thi~a weak point may have been due to a problem with the log periodic dipole array antenna. The azimuth polar radiation plots reveal no nulls_ At 150 MHz the average gain is -- 1.7 d8. At the other frequencies the gain level.c are low.
To plat the data in the form of. Figs:. 18-22 it needs to be normalized to the / wave ref~:rence antenna_ A ~/ wave ar~tenna in theory is equal to 0 dB at its horizon_ ~'o normalizing the date the reference level is subtracted from the antenna under test measured level.
This makes the reference equal to 0. The outer circle of the plot is 0_ This makes the outer circle of the polar plot equal to the performance of: the 1/ wave antenna. In theory a shortened antenna w~.7.1 always be less than a 1/ wave so they will remain inside the outer circle. The plots of Figs. 23-27 show how the antenna i interacts with the light bar. They indicate if the Light bar shows the antenna creating nulls, and if it does how much. In the normalized data the average gain shows how closely the antenna will perform compared to the 1/ wave antenna.
Tn particular, the 150 M~Tz plot of 'F'ig. 7.8 shows good performance. Performance begins to drop off at 155 MH2 as indicated in Fig. 19 and continue:5 at higher frequencie>> as shown by the plots of Fig:3. 20-22 _ A
1U narrow band swept gain by comparison should reveal the width of the band through which the antenna gain remains adequate. Accordingly, the antenna design described hereinabove~ appears to be a good choice i=or Vt-TF. The SWR plot oi= Fig_ 23 shows how well the antenna tunes.
The. pattern plot of Fig _ 2~# illustrates ITHF data from an internal 1}ght bar antenna of the invention. The pattern plot of Fig. 25 illustrates UfTF data from an external light bar of the a.nvention provided with capacitive feed_ 2o It is therefore apparent that the irwention accomplishes its intended objectives. Wr~ile embodiments of the invention have been described in detail, that has been done t~or the purpose of illustration, not limitation. In addition, the various antenna mounting arrangements and antenna feed arrangements and methods Shown and described herein may have application to other situations in addition to the light bar applications disclosed herein.
Fig. 9B is a developed view further i-Llustrating the antenna of Fig. 9A;
Fig. 9C is a developed view further i:~lustrating a portion of the antenna of Fig. 9B;
Fig. 10 is a side elevational view of a light bar antenna arx-angement according to the invention wherein different types of antennas are incorporated in the light bar;
Fig_ 11 is a fragmentary plan view showing a capacitively fed ground plane for use in the antenna of the invention;
Fig. 12A and 128 are side elevational and developed views, respectively, of an antenna of the inventa.on wherein a light bax- metal cover is used as a ground plane;
Fig. 13 is a diagrammatic fragmentary side elevational view, partly in section, illustrating capacitive «nd direct antenna Eeeds, respectively, through the plastic light bar cover in accordance with the invention;
Fig. 1~A is a perspective view of a light bar antenna according to another embodiment of: the invention;
Fig. 1413 is a developed view Further :illustrating the antenna c~f Fig . 14A;
Fig. 14c~ is a developed view further :illustrating a portion of the antenna of Fig. 14B;
Fig. 15 i.s a schematic diagram of a tt~st set up for use on an antenna of the invention;
Fig. 16 is a swept gain plot showing :cesults of a teat performed with the set up of Fig_ 15;
Fig. 17 is an arrangement of data from the test set up of Fig. 15;
Figs. 18 - 22 are pattern plots showiz~g the directivity of the antenna used in the test set up of Fig. 15;
Fig. 23 is a graph further illustrating the data from the test set up of Fig_ 15;
Fig. 24 is a pattern plot illustrating UHF data from one form of light bar antenna of the invention; and Fig. 25 is a pattern plot illustrating UHF data from a light bar of the invention employing e~cternal capacitive feed.
Detailed Description Of The Invention In accordance with the invention, one or more communications antennas are incorporated in the light bar of an em~exgency vehic~.e such as a police car, fire truck, ambulance or tow truck. One advantage of the invention is that_,incorporating the antennas) in the light bar avoids providing additional mounting holes or similar defects in tYie vehicle body which could otherwise adversely affect the body surface and ultimately th.e vehicle resale value. Another advantage is that the a.ntenna(s) is located in the best place for optimum performance on the vehicle. Fender locations can cause nulls in the antenna radiation pattern. A
further advantage is that the location also eliminates the possibility of injury to persons walking near the 1o vehicle whicx~ otherwise is possible with fEnder or trunk mount styles. Still another advantage is that this antenna location will reduce the number of antenna replacements due to breakage in car washes and other extreme environments. A further advantage is that this antenna system provides a much more effect.i.ve use of vehicle ground place :surface area.
Referring now to Fig. 1, there is shown an emergency vehicle l0, such as a police car, provided with a light bar 12 on the roof 14 thereof. The 2_0 enlarged view of Fig. 2 shows the light bar- plastic cover 16 and two communications antennas incorporated within the l:~ght bar in accordance with the: invention_ Tn this embodiment of the invention, :3hown in further deta:~.l in fig. 3, each antenna radiating element is totally contained inside the light bar, i.e. totally within the p:Lastic cover 16. Fig_ 3 shows two short quarter wave antennas 20 and 22. Each '/ wave antenna 20 and 22 is a cop loaded folded monopole that= uses the light bar track 24 as a ground plane. Eaclz antenna is fed by a coaxial cable (not shown in Fig. :3) that is transitioned to coplanar wave-guide or a c.i.rcuit board, i.e. the circuit boards 26 and 28 for antennas 20 and 22, respectively, which feeds the antenna. Low pass, high pass and/or band pass filtering is provided, as needed, for i;~olation. The number of antennas and the arrangements for feeding the antennas shown and described in Figs_ 2 and 3 are merely illustrative, and fewer or greater numbers of antennas and alternative feeding arrangements can be employed.
Referring now to Fig. 4 there is shown another l0 vehicle 40, such as a police car, px-ovided with a light bar 42 on the root 44 thereof. The enlarged view of Fig. 5 shows the light bar plastic cover 46 and three communications antennas 48, 50 and 52 incorporated in the light bar in accordance with the present invention.
In this embodiment of the present invention, shown in further deaail in Fig. 6, each antenna 48, 50 and 52 is partially within and extends fxom the light baz~.
Each antenna uses a ground plane inszde the light bar cover 46. It: is mounted just below the top of the plastic cove- 46 above the light bar cornpor~ents. In particular, t:he brass sheets 54 and 56 are the ground planes for the antenz~as 50 and 52, respectively.
Another similar brass sheet (not shown in Fig. 6) serves as the ground plane for antenna 48. As shown in Fig. 6, the base of e=ach antenna is mounted to the brass sheet ground plane, and the whip of each antenna extends out through an o~~ening provided in plastic cov<sr 46. The antenna whips can be made with nickel titanium wire to resist bending, and they will spring back t=o a vertical.
position after being flexed.
The foregoing ground plane arrangement isolate:
each antenna 48, 50 and 52 preventing the light bar components from affec_aing t:he directiv:ity of the antenna. This is believed to provide improved performance over antennas using the light bar track 60 as the ground plane. Each antenna 48, 50 amd 52 is fed directrly by ~~ coaxial cable (not shown in Fig_ 6). Low pass, high pGiss and/or band pass filtering is provided, as needed foe: isolation. The number of antennas can be fewer or gx'eater than that shown in Figs. ~E-6 and alternative arrangements for feeding the antennas can be employed_ The light bars shown in Figs. 1-6 are of the type having plastic tops. There are also vehicle light bars of the type having metal tope. Fig. 7 shows an antenna 70 according to the present invention inco:cporated in a light bar having a metal top 72 which is u~~ed as the antenna ground plane_ The antenna base 74 is mounted to the light bar metal top 72 and the anteruia whip 76 extends outwardly therefrom. This type is similar to a NMO mount, and the antenna whip length typically will be a quarter wavelength. While only one antenna is shown, more than one can be provided, each being fed by a coaxial cable such as that designated 78 in Fig. 7. Low pass, high pass and/or band pass filtering is provided, as needed, for isolation.
Fig_ 8 shows in further detail an arrangement according to the invention wherein one or more antennas are incorporated in a light bar having a plastic cover and ground ~~lane is provided under the plastic cover.
The metal gx-ound plane is designated 80 ire Fig. B with -~ 9 -antenna 82 beaing mount=ed thereto. The light bar plastic cover is des:i.gnated 84. The overall length of ground plane 80 is J~/2 with the antenna 82 being located at the a/4 mid-po~.nt~ between the ends. The antenna 82 ~.s ~/4 in length. The width dimension of ground plane 80 will_ be constrained by the width of the light bar, but the width of ground plane 80 should be made as large as possible_ Antenna 82 is fed by a capaciti~~re feed 86 and a coax 88, and the coax should pass under nhe ~/4 length section of the ground plane 80 to prevent ~,urrents on the outer surface of the coax from adverse:Ly affecting the antenna ~~peration. The capacitive feed through the plastic dome or cover 8g leaves the light bar integrity intact and protects the internal components from exposure to and damage from water, road salt and the like. This antenna arrangement for operation at and above UHF frequencies demonstrated a good ;Pattern with no bandwidth issues. More than one antenna can be Included in the arrangement, each being fed by a coax as shown, and low pass, hicgh pass and/or band pass filtering is provided, as needed, for isolation.
Fig. 8C shows in further detail the capacit~.ve feed 86 including a capacitive plate 90 and a Mylar cover 92, the covet- being shown in spaced relation from plate 90 for illustra.ta.ons, ~.?~ being understood that cover 92 is secured over' plate 90 after fznal assembly. Fig. 8D
shows the components of one illustrative .dorm of thf~
antenna 82 i.nclud~.ng an end cap 9~ and nut 95, a shrink down component 96, a memory wi,xe 97, an exaernal nut 98, base plate ~~9, screw loo and tape 10~..
For operation at. and below V'HF frequencies, due to the size of the ground plane needed for V~IF~, it is believed that use o~ the light bar track far the ground plane is the best choice. If the light baz~ track is mounted to the roof of a vehicle in a mannE:r such that the track is electrically connected to the roof and hence the body of the vehicle, the light bar track ground plane may be suitable for low band operation.
Such an arrangement i.s shown in Fig. 9 whei:e a light bar 13.o comprise~~ a cover or housing 122 and a light bar track 7.14_ ~~ capacitively-fed antenna 116 uses the light bar bottom txar_k 1.14 as the ground plane. Rs shown in Fig. 9$, antenna x_16 comprises a mast assembly 118 supported by a base assembly 120 mounted on the light bar corer or top 112. A spring base assembly 122 is located between antenna base assembly 1:20 and bottom track 114. :Fig. 9C shows the spring base ,assembly 122 in detail in~=luding a base 124 which is se,~ured to bottom track 114 by screws 125, a Teflon insulator 126, a first coil 127, a second coil 128, a contact pin 129 and a coil housing 130_ A coaxial cable (not shown) ~.s provided for feeding the antenna. This arrangement provides easy transition to coax, easy addition of filters and easy mounting to the light bar track.
Additional antennas can be included in the arrangement.
Low pass, high pass and/or band pass filtering is provided, a~ needed, fox isolation.
Fig. 1Cs il~.ustrates an arrangement according to the invention wherein different antenna stylew can be employed iri a single light bar 140. The v~iF antenna i4a on the left-hand side of_ the arrangement shown in Fig.
l0 utilizes the la,ght bar track 144 as. them ground plane _ 11 in a manner similar t« that illustrated in l~ig. 9. A
bobbin 146 as seen in Fig. ~.0 is included f«r providing a base ~.oadin~~ connection to the VHF antenna as in the arrangement of_ Fzg. 9. The UHF antenna 148 on the right:-hand side of the arrangement shown in Fig. 10 utilizes a UHF ground plane 150 added to the light bar plastic cover 152 in a manner similar to that il3ustrated in Fig. 8. This is illustrated in further detail in Fig. 11 which shows the UHF ground plane 150 added to the plastic cover 132, the UHF feed point 154 for the antenna and the coaxial cable 156 connection thereto for feeding the antenna, and the Mylar cover 158 for proteetirag the capacitive antenna feed_ Fig. 12 provides a detailed showing of haw a light bar metal cover antenna is assembled_ Antenna 170 is mounted on ttae light bar metal top 172 which serves as the ground plane arid a coaxial cable 174 i:c connected to the antenna. Components of antenna x.'70 ex.t:ernal to the light bar corer or housing are the outer end cap 176, mast 178, nut 180, Delr~.n washer 182, external. nut 184 and center conductor 186. Components of antenna 170 internal to 'the light bar covet or housing are a pair of washers 188 and 190, a ground sleeve 192 and an insulator 194.
Fig. 13 illustrates capacitive and direct antenna feeds according to the invention through the plastic light bar cover. A pair o~ antennas 200 and 202 are located on the exterior of a plastic light bar cover 204 and axe Eed by coaxial cables 20& and 208, respectively located within cover 20g. Antenna 200 illustrates the Capacitive feed method according to the ir_vention and antenna 202 illustrates the direct fieed method according to the invention. llntenna 200 includes a whip 210 (a portion of the length being shown) extending ~rom a base structure 212 which is mounted on the cover 204. A pair of metal, i.e. brass, plates 214 and 216 on. opposite surfaces of cover 204 function as the capacitor plates and the plast-is light bar cover 204 furt.ctions as the capacitor dielectric. The center conduetox~ 220 of cable 206 is connecaed to plate 214, and antenna whip 210 is connected elE~ctrically to plate 216.
Antenna 202 illustrates the direct feE.d method according to the present invention and ineJ.udes a whip 224 (a portion of the length being shown) extending from a base structure 226 which is mounted on the cover 204.
The center conductor 230 of cable 208 is connected to one end of a connector element 232 which i:~ threaded through an opening provided in cover 204 and which has the other end thereof connected electrical:Ly to whip 224_ 'rhe direct feed method also can be employed when cover 204 is of metal- in which case connecLer element 232 would be insulated from cover 204.
Both the capacitive and direct feed m~athods according to the invention can be used for any frequency. Both methods also can be employed when the light bar track is used as the ground plane as well- as in situations where the ground plane is located just below the light bar plastic cover.
Fig. 14 shows an arrangement similar to that of Fig. 9 but with components added to the ante~zna to increase versatility. In particular, a spring assembly may be incorporated into the external antenna whip to absorb lateral forces and prevent breakage.
Fuz~thex-more, an e~cternal loading coil may be added to reduce the length of the VHF antenna thereby decreasing the moment arm and reducing the chance for breakage_ Referring first to Fig. 14A, there is shown. a light bar cover or housing 240 which in this example is of plastic, and an antenna mast 242 extending out from housing 240. A loading coil 244 is connected at one axial. end to the antenna nut 246, and coil 244 is connected at the other end to one axial end of a spring assembly 248,. The other end of spring assE~mbly 248 is joined to a base component 250, as shown in Fig. 14B. A
pair of plate's 252, 254 is provided on opposite surfaces of plastic cover 240 to establish a capacit:ive feed in the manner previously described. The arrangement also includes a spring base assembly 260 within cover 240 like the arrangement of Fig. 9. As shown :en Fig. 14C, spring base ,assembly 260 ir~cludes a base W>2 secured to bottom track 264 by screws 266, a Teflon insulator 268, a fix-st coil 270, a second coil 272, a contact pin 274 and a coil housing 2'76.
The invention is illustrated further by the following information obtained from an azimuth pattern z5 and swept gain comparison test conducted vn a light bax-VHF antenna unit. The test set up is shown in F'ig. 15 and she antenna used in the test was a capacitive loaded folded mono>ole for VHF was fitted inside a light bar.
The light bar plastic cover was attached to a track. A
bobbin was mounted at one end to a circuit:. board-planar waveguide combination. which, in turn, was mounted to the track..' The: other end of the bobbin was caupled~:
_ ~L~ _ electrically to the antenna for a base loading connection. The track served a9 the antenna ground plane.
One of the objecti~res of the test is to determine haw the antenna W 11 perform when installed in a light bar. Gain arid directivity of the antennas performance need to be cr~aractex~i zed to show haw the ar~tenna W 11 perform. Then the results are compared to a 1/ wave antenna refex-ence that ie widely used by tree police l0 where the pez~formance is known.
The fol~Lowing equipment was used in the test:
Hewlett Pack<3rd 8753ES network analyzer wil:h an N
calibration lcit, two coaxial test cable as;~emblies, one 20 foot, one 120 foot, each using LMR 300 ~~oax terminated with N connectors. As shown in Fig. 15, the light bar with the V~IF unit installed and ,designated 280 in Fig. Z5 was mounted an a ~0" diameter ground plane that rotated. A log periodic dipole array 282 was set up at 100 feet from the light bax on the ground plane.
The view of the two antennas is unobstructed and the Iog periodic dipole array pointed at the ground plane. The network analyzer was set up near the ground plane. The 20-foot cable was attached in between the VHF unit and the analyzer. Then the 120-foot cable was attached in between the log periodic dipole array and the analyzer.
The analyzexv was then set up for a transmission measurement with markers set up at lSo thZ-ough 170 MHz with SMHz spacing. Marker values were recorded in dB
beginning at: 0 degrees and every 20 degz~ee~s following.
3o When this p<>rtion of the teat was completcad the light bar was removed from the ground plane. Then in the ~.
i center of the ground plane a ,~ wave antenna was installed. This antenna is the reference that the light bar antenna will be compared to. Marker data was taken of this antenna from only one direction. Being mounted in the center of: a round ground plane th~~ antenna will give equal results from any direction. 'hhe results were entered in a excel spreadsheet and plotted. The network analyzer w<~s then set up for a SWR measu:cement of the VHF unit. A standax-d calibration was pe:cformed.
to The swept gain plot of Fig. 7.6 is the result of a transmission measurement from the anaLyzc:r. The data for the raw data crzarts of Fig. 17 comes from thin measurement. The swept gain measurement shows a drop in amplitude at 157 M~~z. At this weak point: the s~.gnal to noise levea_ ~.s h~.gta creating extra error for the 155 MHz plot. Thi~a weak point may have been due to a problem with the log periodic dipole array antenna. The azimuth polar radiation plots reveal no nulls_ At 150 MHz the average gain is -- 1.7 d8. At the other frequencies the gain level.c are low.
To plat the data in the form of. Figs:. 18-22 it needs to be normalized to the / wave ref~:rence antenna_ A ~/ wave ar~tenna in theory is equal to 0 dB at its horizon_ ~'o normalizing the date the reference level is subtracted from the antenna under test measured level.
This makes the reference equal to 0. The outer circle of the plot is 0_ This makes the outer circle of the polar plot equal to the performance of: the 1/ wave antenna. In theory a shortened antenna w~.7.1 always be less than a 1/ wave so they will remain inside the outer circle. The plots of Figs. 23-27 show how the antenna i interacts with the light bar. They indicate if the Light bar shows the antenna creating nulls, and if it does how much. In the normalized data the average gain shows how closely the antenna will perform compared to the 1/ wave antenna.
Tn particular, the 150 M~Tz plot of 'F'ig. 7.8 shows good performance. Performance begins to drop off at 155 MH2 as indicated in Fig. 19 and continue:5 at higher frequencie>> as shown by the plots of Fig:3. 20-22 _ A
1U narrow band swept gain by comparison should reveal the width of the band through which the antenna gain remains adequate. Accordingly, the antenna design described hereinabove~ appears to be a good choice i=or Vt-TF. The SWR plot oi= Fig_ 23 shows how well the antenna tunes.
The. pattern plot of Fig _ 2~# illustrates ITHF data from an internal 1}ght bar antenna of the invention. The pattern plot of Fig. 25 illustrates UfTF data from an external light bar of the a.nvention provided with capacitive feed_ 2o It is therefore apparent that the irwention accomplishes its intended objectives. Wr~ile embodiments of the invention have been described in detail, that has been done t~or the purpose of illustration, not limitation. In addition, the various antenna mounting arrangements and antenna feed arrangements and methods Shown and described herein may have application to other situations in addition to the light bar applications disclosed herein.
Claims (10)
1. An antenna for incorporation in a vehicle light bar having a plastic housing and a metal track therein, t=he antenna comprising:
a) a radiating element totally contained within the light bar plastic housing;
b) the antenna radiating element being operatively associated with the light bar metal track such that the track serves as a around plane for the antenna; and c) means within the light bar hounding for providing a direct feed to the antenna.
a) a radiating element totally contained within the light bar plastic housing;
b) the antenna radiating element being operatively associated with the light bar metal track such that the track serves as a around plane for the antenna; and c) means within the light bar hounding for providing a direct feed to the antenna.
2. The antenna according to claim 1, having an electrical length of a quarter wavelength.
3. The antenna according to claim 1, in the form of a top loaded folded monopole.
4. The antenna according to claim 1, in combination with at least one additional antenna having a radiating element totally contained within the light bar housing, each of the antennas using the light bar metal track as a ground plane and each of the antennas having a direct feed within the light bar housing.
5. An antenna for incorporation in a vehicle light bar having a plastic housing, the antenna comprising:
a) a whip section having one end located outside of the plastic housing and the opposite end extending through an opening in a surface of the housing, a major portion of the whip section being located external to the light bar housing;
b) a base section connected to the opposite end of the whip section and located adjacent an inner portion of the surface of the housing;
c) a metal ground plane element mounted to the antenna base and supported adjacent the inner portion of the surface of the housing; and d) means within the light bar housing for providing a direct feed to the antenna.
a) a whip section having one end located outside of the plastic housing and the opposite end extending through an opening in a surface of the housing, a major portion of the whip section being located external to the light bar housing;
b) a base section connected to the opposite end of the whip section and located adjacent an inner portion of the surface of the housing;
c) a metal ground plane element mounted to the antenna base and supported adjacent the inner portion of the surface of the housing; and d) means within the light bar housing for providing a direct feed to the antenna.
6. The antenna according to claim 5, in combination with at least one additional antenna having a whip section extending through an opening in the housing and having a base section mounted to a metal ground plane element supported adjacent the inner portion of the surface of the housing, each of the antennas having a direct feed within the light bar housing.
7. An antenna for incorporation in a vehicle light bar having a plastic housing, the antenna comprising:
a) an antenna base adjacent an external surface of the plastic housing and an antenna whip extending outwardly from the base;
b) a pair of metal plates provided on opposite surfaces of the plastic housing, one of the metal plates being located between the antenna base and the external surface of the plastic housing; and c) a conductor located within said housing and connected to the other of the metal plates for needing the antenna, the metal plates and plastic housing therebetween providing a capacitive feeding electrical connection between the conductor and the antenna.
a) an antenna base adjacent an external surface of the plastic housing and an antenna whip extending outwardly from the base;
b) a pair of metal plates provided on opposite surfaces of the plastic housing, one of the metal plates being located between the antenna base and the external surface of the plastic housing; and c) a conductor located within said housing and connected to the other of the metal plates for needing the antenna, the metal plates and plastic housing therebetween providing a capacitive feeding electrical connection between the conductor and the antenna.
8. An antenna for incorporation in a vehicle light bar having a housing, the antenna comprising:
a) an antenna base on an external surface of the housing and adjacent an opening extending through the housing:
b) an antenna whip extending outwardly from the base;
c) a conductor located within the housing for providing an electrical feed to the antenna;
and d) a connector element extending through the opening in the housing and connected to the antenna base and to the conductor for completing a direct feeding electrical connection between the conductor and the antenna.
a) an antenna base on an external surface of the housing and adjacent an opening extending through the housing:
b) an antenna whip extending outwardly from the base;
c) a conductor located within the housing for providing an electrical feed to the antenna;
and d) a connector element extending through the opening in the housing and connected to the antenna base and to the conductor for completing a direct feeding electrical connection between the conductor and the antenna.
9. The antenna according to claim 8, wherein the light bar housing is of plastic.
10. The antenna according to claim 8, wherein the light bar housing is of metal and the connector element is insulated from the housing.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US37407102P | 2002-04-18 | 2002-04-18 | |
| US60/374,071 | 2002-04-18 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2426243A1 true CA2426243A1 (en) | 2003-10-18 |
Family
ID=29270510
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2426243 Abandoned CA2426243A1 (en) | 2002-04-18 | 2003-04-17 | Vehicle light bar antennas |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2426243A1 (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7476013B2 (en) | 2006-03-31 | 2009-01-13 | Federal Signal Corporation | Light bar and method for making |
| US7746794B2 (en) | 2006-02-22 | 2010-06-29 | Federal Signal Corporation | Integrated municipal management console |
| US9002313B2 (en) | 2006-02-22 | 2015-04-07 | Federal Signal Corporation | Fully integrated light bar |
| US9346397B2 (en) | 2006-02-22 | 2016-05-24 | Federal Signal Corporation | Self-powered light bar |
-
2003
- 2003-04-17 CA CA 2426243 patent/CA2426243A1/en not_active Abandoned
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7746794B2 (en) | 2006-02-22 | 2010-06-29 | Federal Signal Corporation | Integrated municipal management console |
| US9002313B2 (en) | 2006-02-22 | 2015-04-07 | Federal Signal Corporation | Fully integrated light bar |
| US9346397B2 (en) | 2006-02-22 | 2016-05-24 | Federal Signal Corporation | Self-powered light bar |
| US9878656B2 (en) | 2006-02-22 | 2018-01-30 | Federal Signal Corporation | Self-powered light bar |
| US7476013B2 (en) | 2006-03-31 | 2009-01-13 | Federal Signal Corporation | Light bar and method for making |
| US7905640B2 (en) | 2006-03-31 | 2011-03-15 | Federal Signal Corporation | Light bar and method for making |
| US8636395B2 (en) | 2006-03-31 | 2014-01-28 | Federal Signal Corporation | Light bar and method for making |
| US9550453B2 (en) | 2006-03-31 | 2017-01-24 | Federal Signal Corporation | Light bar and method of making |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| EP1291967B1 (en) | Multifrequency antenna | |
| US5864318A (en) | Composite antenna for cellular and gps communications | |
| US6473056B2 (en) | Multiband antenna | |
| AU687064B2 (en) | Msat mast antenna with reduced frequency scanning | |
| EP0590955B1 (en) | Multiple band antenna | |
| DE102009051605B4 (en) | Highly integrated multi-band fin antenna for a vehicle | |
| CA1287916C (en) | Near-isotropic low-profile microstrip radiator especially suited for use as a mobile vehicle antenna | |
| EP0989629A1 (en) | Vehicular antenna | |
| US6853341B1 (en) | Antenna means | |
| DE602004010089T2 (en) | ANTENNA SYSTEM FOR A MOTOR VEHICLE | |
| EP0637094B1 (en) | Antenna for mobile communication | |
| EP0945917B1 (en) | Antenna arrangement and mobile terminal | |
| US5248988A (en) | Antenna used for a plurality of frequencies in common | |
| KR100871233B1 (en) | Integrated multiservice car antenna | |
| US20100013724A1 (en) | Antenna apparatus | |
| US20020149539A1 (en) | Helical antenna, antenna unit, composite antenna | |
| US6927736B1 (en) | System and method for integrating antennas into a vehicle rear-deck spoiler | |
| US5406296A (en) | Three-wave antenna for vehicles | |
| US5311201A (en) | Multi-band antenna | |
| DE112008001688T5 (en) | Antenna system for the remote control of an application in the automotive sector | |
| US20040036659A1 (en) | Multi-band vehicular blade antenna | |
| US20020020034A1 (en) | Windshield wiper arm | |
| CA1123511A (en) | Wideband antenna with frequency dependent ferrite core inductor | |
| CA2426243A1 (en) | Vehicle light bar antennas | |
| GB2400497A (en) | Vehicle antenna for dual band mobile communications and AM/FM reception |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Dead |