US3599214A

US3599214A - Automobile windshield antenna

Info

Publication number: US3599214A
Application number: US805517A
Authority: US
Inventors: John Altmayer
Original assignee: NEW TRONICS CORP
Current assignee: NEW TRONICS CORP
Priority date: 1969-03-10
Filing date: 1969-03-10
Publication date: 1971-08-10
Anticipated expiration: 1988-08-10

Abstract

A nondirectional automobile receiver antenna which may be utilized on either the low frequency broadcast band or the very high frequency, frequency-modulated (FM) band, and which is adapted to be adhesively attached to or embedded within the windshield of an automobile.

Description

United States Patent John Altmayer Euclid, Ohio Mar. 10, 1969 Aug. 10, 1971 New-Tronics Corporation Brook Park, Ohio Inventor Ap l. No. Filed Patented Assignee AUTOMOBILE WINDSHIELD ANTENNA .12 Claims, 7 Drawing Figs.

' U.S; C l 343/713, 343/722, 343/724, 343/803 Int. Cl H0lq 1/32 Field of Search 343/711,

References Cited UNITED STATES PATENTS 3,414,902 12/1968 Shaw 343/713 FOREIGN PATENTS 800,577 8/1958 Great Britain Primary Examiner-Eli Lieberman Atrorney-Meyer, Tilberry and Body ABSTRACT: A nondirectional automobile receiver antenna which may be utilized on either the low frequency broadcast band or the very high frequency, frequency-modulated (FM) band, and which is ada pted'to be adhe'sively attached to or embedded within the windshield of an automobile' PATENTED AUBIOIBYI 3,599,214

I NVEN TOR. JOHN ALTMAYER I4 46 m Mam,

ATTORNEYS ous applications which require a nondirectional, multiband radio antenna.

In thepast, substantially all automobile radio antennas have been of the vertical type, and have generally been mounted on an external surface, such as a fender, of the automobile. Such antennas are inherently subject to being broken upon striking stationary objects, such as tree branches, etcetera.

Automobile antennas of the type to which this invention pertains have heretofore normally included a generally looptypeantenna designed to be embedded within, the glass pane around the perimeter of an automobile wind shield. Since the antenna element must be embedded in the glass pane at the time the windshield is manufactured, it is not practicable to install an antenna of this type after the automobile has beenassem bled. In addition, these generally loop-type antennas have exhibited the characteristic of having extremely directional reception characteristics, i.e., the signal strength of the received signal was dependent upon the alignment of the automobile with respect to the radio station. Astill further problem associated with this type of antenna is that the antenna is of a configuration such that the antenna could ,be utilized on only a single band of frequencies, for examplegthe'amplitude-modulated (AM) band, which is generally a relative low band of frequencies, such as 550 to 1600 kilohertz.

The present invention'is directed toward a new and improved antenna which overcomesall of the above referred-to problems. and others, and provides an antenna'which is simple in construction andinstallation.

'ln accordance with the present invention there is provided a multiband antenna adapted to be attached to or embedded within a dielectric support, such as an automobile window or windshield, and comprising a first and second elongated, generally U-shaped conductive member each having a pair of terminals; one of the terminals of the first U-shapedmember being connected to a corresponding terminal of the second U- shaped conductive member and the other terminal of the first U-shaped member being adapted to be coupled to one conductor of a transmission line; and capacitance means associated with the second U-shaped conductive member and exhibiting the characteristic of providing a capacitive reactance with respect to the second U-s'haped conductive member, and the capacitance means being adapted to be connected to the other conductor of the transmission line. The capacitance has a value such that at the lower frequencies, it presents a high impedance or open circuit and the antenna functions as a folded long wire antenna, and at the higher frequencies the capacity presents a low impedance or short circuit and the antenna functions as a folded dipole usually resonant at or near the frequency being received. In accordance with a more limited aspect of the present in vention, the second U-shaped conductive member has a first.

and second leg. the first leg of the second U-shaped conductive member is connected to one of the terminals the first U- shaped conductive member; and, the capacitance means inof the capacitor is adapted to be coupled to the other conductor of the transmission line.

In accordance with a still more limited aspect-of the present invention, the U-shaped conductive members carry means for adhesively attaching the conductive members to an automobile window, one of the U-shaped members is attached to the window of an automobile in a generally vertical plane, and the other U-shaped member is attached to the window in a generally horizontal plane to thereby provide an antenna which exhibits substantially nondirectional reception characteristics.

The primary object of the present invention is to provide a nondirectional, multiband antenna adapted to be mounted on or embedded in a window orwindshield of an automobile.

Another object of the present invention is to provide a nondirectional, multiband antenna of a configuration adapted to be mounted on or embedded within the windshield or an automobile without obstructing the forward visibility of the driver. v t v 1 A still further object of the present invention is to provide an automobile antenna of an electrical configuration such that the antenna may be utilized with conventional amplitude modulated (AM), i.e,,-550 to 1600 kilohertz, and/or frequency modulated FM i. e., 88 to 108 megahertz, automobile receivers. I

In accordance with another object of the present invention, there' is provided an automobile radio antenna which is mounted within the interior of anautomobile, and whichjm ay be use as a direct replacement for conventional fendermounted automobile antennas. I i

in accordance with a still further object of the present invention, there is provided an antenna for an automobile receiver which may be located on the periphery of the automobile windshield, and which may be attached to the windshield after the automobile is assembled.

In accordance with a still further aspect of the present invention, there is provided an antenna which may be utilized with amplitude modulated (AM) and/or frequency modulated FM automabile. radios, which may be mounted within a window or windshield or anautomobile, and which is a direct replacement for conventional-fender-mounted automobile antennas.

These and other objects and advantages of the present invention will become apparentfrom the followingdescription of the preferred embodiment of the invention as read in connection with the accompanying drawings in which:

FIG. 1 is an elevational view illustrating the preferred embodiment of the present invention attached to an automobile windshield; v

FIG. 2 is a sectional view taken generally along line 2-2 of FIG. 1;

eludes an elongated conductive element which extends substantially parallel to the second leg of the second Ushaped conductive member, and the elongated conductive element includes a terminal adapted to be coupled to the other conductor ofthe transmission line.

In accordance with another embodiment of the present invention, the capacitance means is comprised of a capacitor having one terminal connected to the other terminal of the second U-shaped conductive member and the other terminal FIG. 3 is an expanded sectional view of the embodiment shown in FIG. 1; v

FIGS. 4, 5 and 6 are schematic illustrations of the embodiment of the present invention shown in FIG. 1; and, FIG. 7 is an elevational view illustrating a second embodiment of the present invention.

Referring now to the drawings wherein the showings are'for purposes of illustrating preferred embodiments of the present invention, and not for purposes of limiting same, FIG. 1 illustrates an antenna constructed in accordance with the present invention, and generally comprises an antenna element 10 attached to an automobile windshield l2, and connected to a feedline 14. The antenna element 10 is comprised of a pair of elongated, generally U-shaped

conductive members

16 and 18, each having a pair of

terminals

20, 22 and 24, 26, respectively. Preferably, U-shaped conductive members-l6 and 18 are comprised of'a thin, copper wire extendingin a generally elongated U-shaped fashion, and are preferably completely encased or embedded in thin, flexible, transparent, plastic rib--

bons

28 and 30, respectively. The thin

plastic ribbons

28 and 30 are attached to an automobile window or windshield with an adhesive material, although other suitable methods of attaching the U-shaped conductive members, within the scope of this invention, are contemplated. Further, it is also contemplated that the U-shaped

conductive members

16 and 18 could be completely embedded within the glass pane of an automobile window or windshield, and may take the form of wire conductors as shown or could be applied as thin film conductive material interposed within the glass pane.

As illustrated in FIG. 1, the U-shaped conductive member 16 is adhesively attached to the windshield in a generally vertical plane, and conductive member 18 is attached to the windshield in a generally horizontal plane, thereby providing a nondirectional antenna, as well as an antenna having a configuration such that the forward visibility of the driver is not obstructed. It is contemplated, however, that the U-shap ed conductive members could both extend either in a horizontal or vertical plane.

Reference is now made to FIG. 3, which more particularly illustrates the electrical circuit arrangement. Terminal 20 of U-shaped member 18 is connected to terminal 24 of 'U-shaped member 16, terminal 22 of U-shaped member 18 is connected to a conductor 38 of the feedline or transmission line 14, and terminal 26 of U-shaped member 16 is connected through a capacitor 40 to the other conductor 42 of transmission line 14. The U-shaped

conductive member

16 and 18 are of a length and'spacing between the legs thereof such that the antenna is approximately resonate when operated on the very high frequency band of frequencies.

Capacitor-40, as well as the circuit connections between the

conductors

38, 42 of transmission line 14 and't'erminals 20,

'22, 24, and 26 of U-shaped

conductive members

16, 18 is completely encapsulated in a disk-shaped enclosure 43, preferably formed of an epoxy material.

Conductor 42 of transmission line 14 is. connected to the outer portion of a connector 46, which takes the form'of a conventional bayonet-type antenna plug, and the other con- 'ductor 38 of transmission line 14 is connected to the center portion of connector 46. 1 v

Reference is now made to FIG. 7 which illustrates a second embodiment of the present invention, and which is somewhat similarto the preferred embodiment as illustrated in FIG. 3; therefore, corresponding elements are designated with the same element numeral. As is apparent from FIG. 7, capacitor 40 in the preferred embodiment is eliminated and a single elongated conductive member of wire 50, which extends substantially parallel to the free leg of U-shaped member is substitutedtherefor. Thus, terminal 26 of U-shaped member 16 I terminates without being connected to any other circuit element, and elongated conductor 50 extends substantially parallel to the free leg of U-shaped member 16 and is connected to conductor 42 of transmission line 14.

Reference is now made to FIGS. 4 through 6 which illustrate a schematic diagram of the electrical circuit representative of the antennas shown in FIGS. 3 and 7. Capacitor 40, i which in the preferred embodiment is a 40 picofarad capacitor, exhibits the characteristic of providing a high impedance to the flow of current, as illustrated in FIG. 6, when the antenna is operated on the lower frequency bands, such as the amplitude-modulated (AM) broadcast band, i.e., 550 to 1600 kilohertz'. As is apparent from FIG. 6, when the capacitor exhibits a high impedance or approximately an open circuit impedance, the antenna appears as a folded,.long-wire type antenna connected to the center portion of connector 46. When the antenna is operated on a relatively higher frequency band, capacitor 40 exhibits the characteristic of providing a-low impedance to the flow of current as illustrated in FIG. 5. With capacitor 40 exhibiting a low impedance or approximately a short circuit impedance, the antenna appears to be a generally folded-dipole type antenna in which one of the legs extends in a vertical plane and the other leg extends in a horizontal plane. Since the antenna configurations resulting from low and high frequency operation include a generally vertical element as well as a horizontal element, the antenna exhibits a relatively high gain factor as well as nondirectional reception characteristics.

periorreception characteristics on the lower frequency; therefore, since capacitance element 40 exhibits the characteristic of providing a high impedance to the flow of current when the antenna is operated on the low frequency band, the antenna appears as a generally long-wire type antenna on this band of frequencies thereby providing superior reception on this band. In addition, since U-shaped member 16 extends in a generally vertical manner, the reception characteristics of the antenna are substantially nondirectional in nature. When the antenna is operated on a very high frequency band, for example the frequency-modulated FM band, capacitance element 40 exhibits the characteristic of providingsubstantially a short circuit to the flow of .current and the antenna appears as a generally folded dipole-type antenna which inherently pro- TABLE I APPROXIMATE ELEMENT VALUE OR DIMENSION Capacitor 40 40 picofarad Length of U-shaped 15 inches members Distance between legs 3/16 inch of U-shaped member The invention has been described in connection with the particular preferred embodiment, but is not to be limited to same. Various modifications may be made without departing from the scope and spirit of the present invention as defined by the appended claims.

Thus having described my invention, I claim:

'1. An antenna for receiving radio frequency signals which comprises a dielectric support member, a first and second elongated generally U-shaped conductive member each having one terminal in common and the other terminals located in spaced adjacent relationship to each other, said members operatively affixed along their full length to said 3 support member, the other of said terminals of said members adapted to be coupled to a transmission line, and capacitance means between the other terminal of one of said members and its respective transmission line which capacitance means is characterized by exhibiting an open circuit to the flow of current when the antenna is operated on a predetermined first band of radio frequencies and a short circuit when the antenna is operated on a relative high band of radio frequencies with respect to said first band of frequencies;

2. An antenna according to claim 1 where said capacitance means is operatively affixed to said support member, and where the support member is a windshield for use in a vehicle.

3. An antenna as defined in claim 1 wherein said second U- shaped conductive member includes a first and second leg, said first leg of said second U-shaped conductive member is connected to one of said terminals of said first U-shaped conductive member, said capacitance means is an elongated conductive element which extends substantially parallel to said second leg ofsaid second U-shaped conductive member; and,

said elongated conductive element includes a terminal adapted to be coupled to said other conductor of a said transmission line.

4. An antenna as defined in claim 1 wherein said capacitance means is comprised of a capacitor having one terminal connected to said other terminal of said second U- shaped conductive member and the other terminal of said capacitor being adapted to be coupled to said other conductor ofa said transmission line.

5. An antenna as defined in claim 1 including means carried by said each U-shaped conductive member for attachably securing said conductive member to a dielectric support member.

6. An antenna as defined in claim 5 wherein said securing means is an adhesive means carried by each said U-shaped member for adhesively attaching said U-shaped members to a said dielectric support member.

7. An antenna as defined in claim 6 wherein said U-shaped conductive members are attached to a dielectric sheet; and,

adhesive means is superimposed on said dielectric sheet for adhesively attaching said dielectric to a said dielectric support to thereby provide support for said U-shaped conductive members.

8. An antenna as defined in claim 6 wherein said U-shaped conductive members are completely encased in a dielectric sheet; and,

adhesive means is superimposed on said dielectric sheet for adhesively attaching said dielectric sheet to a said dielectric support to thereby support said U-shaped conductive members.

9. An antenna as defined in claim 6 wherein each said U- shaped conductive member is completely embedded in a flexible transparent dielectric ribbon; and,

adhesive means carried by each said dielectric ribbon for adhesively attaching each said ribbon to a said dielectric support member to thereby provide support for each said U-shaped conductive member.

10. An antenna as defined in claim 9 including a dielectric support member comprised of a sheet of transparent dielectric material; and,

each flexible dielectric ribbon is adhesively bonded to said sheet of transparent dielectric material.

11. An antenna as defined in claim 10 wherein said dielectric support member is an automobile windshield.

12. An antenna as defined in claim 1] wherein one of said U-shaped members is attached to said windshield in a generally vertical plane, and the other of said U-shaped members is attached to said windshield in a generally horizontal plane to thereby provide an antenna which exhibits substantially nondirectional reception characteristics.

Claims

1. An antenna for receiving radio frequency signals which comprises a dielectric support member, a first and second elongated generally U-shaped conductive member each having one terminal in common and the other terminals located in spaced adjacent relationship to each other, said members operatively affixed along their full length to said support member, the other of said terminals of said members adapted to be coupled to a transmission line, and capacitance means betWeen the other terminal of one of said members and its respective transmission line which capacitance means is characterized by exhibiting an open circuit to the flow of current when the antenna is operated on a predetermined first band of radio frequencies and a short circuit when the antenna is operated on a relative high band of radio frequencies with respect to said first band of frequencies.

3. An antenna as defined in claim 1 wherein said second U-shaped conductive member includes a first and second leg, said first leg of said second U-shaped conductive member is connected to one of said terminals of said first U-shaped conductive member, said capacitance means is an elongated conductive element which extends substantially parallel to said second leg of said second U-shaped conductive member; and, said elongated conductive element includes a terminal adapted to be coupled to said other conductor of a said transmission line.

4. An antenna as defined in claim 1 wherein said capacitance means is comprised of a capacitor having one terminal connected to said other terminal of said second U-shaped conductive member and the other terminal of said capacitor being adapted to be coupled to said other conductor of a said transmission line.

5. An antenna as defined in claim 1 including means carried by each said U-shaped conductive member for attachably securing said conductive member to a dielectric support member.

7. An antenna as defined in claim 6 wherein said U-shaped conductive members are attached to a dielectric sheet; and, adhesive means is superimposed on said dielectric sheet for adhesively attaching said dielectric to a said dielectric support to thereby provide support for said U-shaped conductive members.

8. An antenna as defined in claim 6 wherein said U-shaped conductive members are completely encased in a dielectric sheet; and, adhesive means is superimposed on said dielectric sheet for adhesively attaching said dielectric sheet to a said dielectric support to thereby support said U-shaped conductive members.

9. An antenna as defined in claim 6 wherein each said U-shaped conductive member is completely embedded in a flexible transparent dielectric ribbon; and, adhesive means carried by each said dielectric ribbon for adhesively attaching each said ribbon to a said dielectric support member to thereby provide support for each said U-shaped conductive member.

10. An antenna as defined in claim 9 including a dielectric support member comprised of a sheet of transparent dielectric material; and, each flexible dielectric ribbon is adhesively bonded to said sheet of transparent dielectric material.

12. An antenna as defined in claim 11 wherein one of said U-shaped members is attached to said windshield in a generally vertical plane, and the other of said U-shaped members is attached to said windshield in a generally horizontal plane to thereby provide an antenna which exhibits substantially nondirectional reception characteristics.