US2094475A - Collapsible antenna for vehicles - Google Patents

Description

Sept. 28, 1937. P. J. SCHWARZHAUPT COLLAPIBLE ANTENNA FOR VEHICLES Filed Jan. 26, 1935 Inventor Paul J. 5chwar-zhaugpt Attorney.

Patented Sept. 28, 1937 UNITED STATES COLLAPSIBLE ANTENNA FOR VEHICLES Paul J. Schwarzhaupt, Scotia, N. Y., assignor to General Electric Company, a corporation of New York Application January 26, 1935 Serial No. 3,623

8 Claims.

My invention relates to antenna systems for radio-equipped vehicles, particularly to antennas of the mast type for use with radio apparatus installed on motor cars, and its object is to provide '5 an antenna of this character which is not liable to damage or impaired efliciency while the vehicle is moving at any speed.

It is common practice in radio equipped motor cars such as police prowl cars to mount a transmitting antenna at the rear of the car. Such an antenna may comprise a tubular structure or mast several feet in height, eight feet for example. A considerable portion of an antenna mast of this character therefore projects upwardly two or three feet above the roof level of the car, and the mast is endangered, during travel of the vehicle, by overhanging limbs of trees, low doorways, or other obstacles. It is desirable therefore that a flexible mounting of the mast be provided so disposed that in case a bending force due to the striking of the mast against an obstacle is exerted thereon, the mast or a portion thereof may bend and pass under the obstacle, thereafter returning immediately to normal operating position.

In accordance with my invention the projecting upper end or upper portion of the mast is flexibly mounted on a lower portion, a flexible joint being provided between the two portions, together with a spring means associated with the cooperating upper and lower mast portions to return the upper portion to normal position after being bent and to hold the upper portion thereafter rigidly in position on the lower portion. Preferablya ball member is provided which is held in position between the two portions of the mast by the spring means, which may be mounted within the mast, the ball member and the ends of the mast portions thereby forming a ball-andsocket joint.

; It is further desirable in the above-describedantenna systems which are designed particularly for-short-wa-ve police radio transmission, that a capacitance member or area be provided at the top of the antenna and an inductance member or coil be connected between'the capacity member and the antenna proper. Important advantages maybe obtained by such an arrangement of inductance coil and capacitance area, the coil and capacity being proportioned to produce desired current distribution in the radiating portion of the antenna. The arrangement of inductance coil and capacitance area per se is described and claimed in a co-pending application, Serial No.

727,409, entitled Antennae, filed on May 25, 1934 by Clifford A. Nickle, and assigned to the same assignee as my present application.

In the latter patent application the capacitance area is shown as constituted by a spherical body or by a hollow cylinder. I have found, however, that with capacitance members of such form used on the antenna of a radio equipped vehicle, the wind pressure when the vehicle is moving tends to tip the antenna and thereby to decrease its effective height. In accordance with 0 my present invention this difiiculty :is overcome by making the capacitance memberof streamlined form. The member vis preferably hollow to enclose the inductance coil which is electrically connected between the capacitance member and the antenna mast. In its preferred form the streamlined capacitance member is so mounted on the mast as to extend rearwardly therefrom, thereby eliminating the possibility of damage or the ripping off of the member due to catching in the limbs of trees or by contact with other obstacles.

My invention will be better understood from the followingdescription when considered in connection with the accompanying drawing andits 5 scope will be pointed out in the appended. claims.

Referring 'to'the drawing, Fig. 1 is a fragmentary side-elevational view of a radio-equipped motor vehicle provided with a transmitterantenna in which my invention has been embodied; Fig. 2 is a fragmentary enlarged view in section of the flexible joint portion of the transmitter mast shown in Fig. 1; Fig. 3 is a side elevational view, partially in section, of a streamlined capacitance member for a radio mast, in accordance with my invention; and Fig. 4 is a top plan sectional view of a streamlined-capacitance member having a modified form of mounting on the radio mast.

In Fig. 1, the numeral l0 indicates a vehicle '40 which may be a police prowl car, equipped with radio apparatus comprising transmitter equipment ll within the vehicle and a transmitter mast or rod antenna l2 of aluminum or other suitable tubing supported by a lower or step insulator l3 which is fastened on a bracket l4, and by an upper insulator l5 fastened on a bracket I6. The mast l2 comprises, in the present embodiment of the invention, a lower or fixed portion I! and an upper portion l8 which isbendable with respect to lower portion 11 in a manner to be described hereinafter. Suitable connection of the mast l2 with the transmitter equipment H is established by a clamp IS, a lead 20 and-a lead-in bushing 2|. The clamp I9 .39. It 35 of the casing and gain access to the inside of tubing of the same diameter as that of the lower portion i'i.

Referring more particularly to Fig. 2, in order that the upper portion l8 may be bent withrelation to the lower portion to any desired degree and thereafter returned to and held rigidly in normal position as shown in Fig. 1, a flexible joint means is interposed between the upper and lower mast portions. This joint means, in the present embodiment of my invention, comprises a member 22, preferably of general ball shape, which may have a flange or rim portion 23 and which is adapted to be held rockably between end members, or the ends 24 and 25 themselves, of the upper and lower mast portions H and I8 respectively, the rim 23 being gripped between the edges of the tube ends 24, 25. A spring means 26 is provided, which is anchored at its extremities 21 and 28 to the upper and lower mast portions [1 and i8 respectively, to maintain a spring pressure tending to hold the ends 24 and 25 7 against opposite sides of the interposed ball member 22. Preferably the member 22 is provided with a central aperture 29 flaring outwardly to the upper and lower surfaces of the member, through which aperture passes a portion 30 of the spring means 26. preferably constituted by a coil spring 3| housed within one of the mast portions, as in lower portion l1, and the portion 30 which may be a cable passing into the other portion of the mast.

In assembling the above-described joint means for mast l2, the lower end of the spring 3| is anchored in a plug 32 which may be secured at the proper point in mast portion H by any suitable means. The upper end of spring 3| is hooked to the cable 30 which passes through the opening 29 of ball member 22 and into the upper mast portion or tube [8. The cable 30 is pulled with suitable power tools thus stretching the spring 3|. As soon as the tension of the spring is sufficient, the cable 30 is anchored in tube l8, as by locking, in proper position within the tube, a plug 33 to which the cable is connected.

In operation of the flexible joint means shown in Figs. 1 and 2, the tension of spring 3| holds the mast portions I1 and I8 in line in normal operation of the radio-equipped vehicle It). If, however, the upper portion [8 encounters an obstacle, the bending force exerted on member I8 causes the latter to swing about the resilient ball-andsocket joint constituted by the ball member 22 and, the ends 24, 25 of the fixed and movable mast portions H, I 8, the rounded ends of the aperture 29 in member ZZ'protecting the cable from damage due to short bends which might otherwise injure the cable strands. As soon as the bent over portion [8 is released from the obstacle as by passing thereunder, the pull of the spring 3i causes the upper mast portion l8 to snap back into normal position, in line with fixed lower mast portion II.

In Fig. 3 the numeral 34 indicates a capacie tance member in the form of a hollow casing having two halves 35 and 3% held together at their flanged edges as by screws 3! and enclosing an inductance coil 38 mounted is thus possible to remove the upper half the casing. Between the lower part 35 of the casing and the upper end of mast portion 18 is The spring means 26 is on a coil form .53, and lead 54 to the may be moved up or down to obtain proper tuninterposed an insulating member or plate 40 connected to the casing part 35 as by screws H. To fasten plate 49 to the mast portion [8 a plug 42 is driven into the end of mast portion l8 and held in place by a set screw 43, and the plate 40 is drawn against the plug 42 and the end of mast portion [8 as by a screw 44. The screw 44 extends considerably above the insulating plate 49 and supports a bracket 45 to which one end of coil 38 and of coil form 39 respectively are fastened. Coil form 39 is fastened at its otherend to thecasing part 35 by a bracket 46 to which the other end of coil 38 is connected.

With the mounting means for capacitance member 34 on theupper end of mast portion arranged as above described, the capacitance member 34 is not electrically connected directly to the antenna mast. On the contrary an inductance member, coil 38, is electrically connected between the extremity of the antenna mast and the capacitance member. By properly proportioning the area of the capacitance member 34 and the inductance of the coil 38 the desired current distribution in the antenna system for optimum transmission is obtained. For further description of the operation of the antenna system comprising such a capacitance area and inductance as shown herein, reference is made to the hereinbefore mentioned application, Serial No. 727,409.

It will be observed thatin practice a capacitance member mounted onthe top of a transmitting antenna such as herein described must provide considerable area. Further, it is desirable, in order to protect the coil and to provide an assembly as compact as possible, to mount the inductance coil within the capaci tance member. The capacitance member is, therefore, necessarily of considerable size. But since this member is mounted at the top of the antenna mast, the bending force due to the presence of this relatively large area of the capacitance member, which is acted on by Wind pressure when the vehicle is in motion, tends to overcome the restoring force of spring 3i, and to rock the upper mast portion is out of line with the fixed mast portion I7, thereby decreasing the effective height of the antenna. In order to overcome the tendency to bending of the mast by wind pressure acting on the capacitance member and at the same time to permit the use of a capacitance member of relatively large area at the top of the mast, I have provided that the casing 34 constituting the capacitance area be of streamline form, the casing being formed, for the purpose of providing an approximately true streamline shape, in substantially ellipsoidal form but havinga pointed end rearwardly of the mast, as shown in Fig. 3.

In Fig. 4.1 have shown an alternative means for mounting the capacitance member on the 7 radio mast l2. As in the arrangement shown inFig. 3, the capacitance member, designated by the numeral 47, is in the form of two halves 48, 49 heldtogether at their flanged edges. In Fig. 4, however, the streamlined casing 41 is supported at its leading endon one side of the upper end of the mast by'a clamp 50 and an' insulation member 5!. One end of the coil 38 in Fig. 4 is electrically connected through the coil-formsupporting bracket 46 to one section of the casing as in Fig. 3, but the other end of the 'coil in Fig. 4 is connected through supporting bracket 45, stud 52 insulated from the casing by insulator clamp 50 which'iselectrically connected to the upper portion l8 of the mast. Therefore in the form of the capacitance area and inductance coil mounting shown in Fig. 4, since the casing 4's is connected behind the mast and projects rearwardly therefrom as shown in Fig. l, the casing cannot be damaged or ripped from the mast by being caught in the limbs of trees or by contact with other like obstacles when the vehicle is in motion.

My invention has been described herein in particular embodiments for purposes of illustration. It is to be understood, however, that the invention is susceptible of various changes and modiiications, and that by the appended claims I intend to cover any such modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. The combination with a radio equipped vehicle, of an antenna extending in normal operation a substantial distance above said vehicle, said antenna comprising two portions and having a joint between said portions and spring means connected across said joint whereby the upper portion of said antenna is bendable from its normal position upon application of a bending force thereto and returnable to said normal position upon discontinuance of said bending force.

2. The combination with a radio equipped vehicle, of an antenna mast comprising an upper portion and a lower portion, means providing a flexible joint between adjacent ends of said portions, and resilient means connected between said portions, whereby said upper portion is bend able from its normal position upon application of a bending force thereto and whereby said upper portion is returned to and maintained rigidly in normal position upon discontinuance of said bending force.

3. An antenna mast comprising only two sections, each of said sections functioning throughout its length as an antenna, a ball-and-socket joint interposed between adjacent ends of said sections, and spring means connected to said sections whereby said mast is maintained in normal position until changed from said position by application of a bending force to the upper one of said sections.

4. An antenna mast comprising two hollow sections only, each of said sections functioning throughout its length as an antenna, and means whereby one section is bendable from its normal position with respect to the other section, said means including a perforated ball member havin a rim portion, said ball member being interposed between adjacent ends of said sections and forming with said ends a ball-and-socket joint, except for said rim portion said ball member being completely enclosed within said mast in normal position of said sections, and a resilient means within said sections anchored at its opposite extremities to said sections respectively and having .a portion passing through said perforated ball member.

5. The combination with a radio-equipped vehicle, of an antenna comprising a jointed antenna mast bend-able upon application thereto of a bending force and a capacitor substantially of ellipsoidal shape connected to said mast at the upper end thereof, the entire body of said capacitor extending rearwardly of said mast.

6. The combination with a radio-equipped vehicle, of an antenna apparatus comprising an antenna mast having its upper portion exposed to wind pressure and a capacitance member of substantially ellipsoidal shape connected to said upper portion of said mast, the entire body of said capacitance member extending rearwardly of said mast.

7. The combination with a radio-equipped vehicle, of an antenna apparatus comprising an antenna mast extending upwardly from said vehicle and a hollow capacitance member of substantially ellipsoidal form connected to said mast at a point adjacent the upper end thereof, the entire body of said capacitance member extending rearwardly of said mast.

8. An antenna apparatus for a radio-equipped vehicle comprising, an antenna mast bendable upon application thereto of a bending force, an inductance coil connected at one extremity thereof to the upper end of said mast, and a hollow capacitance member of substantially ellipsoidal form enclosing said coil, said capacitance member being mechanically connected to said upper end of said mast and electrically connected to the other extremity of said coil, the entire body of said capacitance member extending rearwardly of said mast.

PAUL J. SCHWARZHAUPT.

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