US2129514A - Radio antenna apparatus - Google Patents

Description

Sept. 6, 1938. s. M. WERTHEIMER RADIO ANTENNA APPARATUS Filed March 25, 1936 2 Sheets-Sheet 1 7 Samuel [17.

INVENTOR.

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ATT NEY.

Sept. 6, 1938. 5 wERTHElMER 2,129,514

RADIO ANTENNA APPARATUS Filed March 25, 1936 2 Sheets-Sheet 2 Z 5 9 r/dq Z 44 %4 a a J4 INVEN TOR.

BY @EY Patented Sept. 6, 1938 UNITED STATES RADIO ANTENNA APPARATUS Samuel M. Wertheimer, Brooklyn, N. Y., assignor to Birnbach Radio Company, Inc., New York,

N. Y., I a corporation of New York Application March 25, 1936, Serial No. 70,862

4 Claims.

This invention relates to electrical apparatus generally. More particularly, this invention relates to radio antenna systems and coupling systerms for connecting same to signaling apparatus.

An object of this invention is to provide an antenna arrangement for signaling apparatus which will function efficiently over one or more bands of signal frequencies which may be widely separated.

Another object of this invention is to provide an antenna arrangement for signaling systems, particularly receivers, which is simple in construction, easily installed, and adapted to function efiiciently on any one or more of a number of different frequencies or frequency bands.

Another object of this invention is to provide an antenna transformer adapted to be connected into the antenna pick-up conductor at or near the midpoint thereof and render the antenna more efficient as a collector or absorption circuit for signals of widely different frequencies.

Still another object of this invention is to provide an antenna having two sections of electrical unequal length, divided by an electrical network whereby the whole antenna may be used as an efficient absorption member for relatively long waves and only the short section may be used as an absorption member of waves of shorter length. 30 A further object of this invention is to provide a high frequency transformer and coupling unit having a pair of windings adapted to be connected in series with sections of the antenna pick-up conductor and having an impedance adapted to couple the sections of the antenna as a loading element at low signal frequencies and function as a choke at higher signal frequencies.

Other and further objects of this invention 40 will be apparent from the following specification and claims.

In accordance with this invention I provide a coupling network for connecting an antenna to signaling apparatus in an efficient and effective manner. My invention may be employed with antenna. systems of conventional design, particularly those embodying a length of wire supported between two or more insulators well above the ground, roofs, and similar objects. In one form of this invention, which is the preferred form, the antenna is divided into two substantially unequal sections and a winding of the coupling network is connected between these sections. In another form of this invention the antenna sections are made substantially equal and windings of the coupling network are connected between these sections and the lead-in. conductors. In the latter form these windings of the coupling network are connected substantially at their midpoints to an impedance unit which serves as a loading coil at relatively low signaling frequencies, for example, the frequencies now used for program broadcasting purposes. At the higher frequencies, for

example, five megacycles, this impedance unit serves as a choke coil and the antenna functions as a doublet antenna.

Further details of this invention will be set forth in the following specification and drawings in which, briefly, Fig. 1 illustrates the circuit 5 diagram showing an embodiment of my invention; Fig. 1a, shows another form of this invention; Figs. 2 and 3 are views of the exterior of the antenna coupling network casing; and Figs. 4,

5, and 6 show details of construction of the network coils and. housing.

Referring in more detail to Figure 1 of the drawings, reference numeralsland II designate sections of an antenna conductor, supported by the insulators l2 and I3 attached to the free ends of the conductor sections. A coupling unit l4, having a housing of insulation material as more clearly illustrated in the following figures of the drawings, is connected to the antenna sections I and II, respectively, and coil 11 connected between points IB and I9 of'coils l and I6, respectively. Thus the inductance l1 joins the points I8 and I9 which are substantially in the electrical centers of the coils I5 and Hi. The antenna conductor section I 0 connected to one end of the coil I5, is of substantially the same length as the conductor II which is connected to one end of the coil I6, although it is obvious that,

sections may be of different lengths depending upon the surroundings in which the antenna is used.

Ends 22 and 23 of the twisted conductors 20 and 2| are connected to the opposite ends of the coils l5 and I6. These conductors 20 and 2| are insulated from each other by rubber or similar material and twisted in order to reduce their efficiency as interference pick-up members and if desired, straight conductors encased in a flexible shield of braided metallic material, which isconnected to ground, may be used in place of twisted condu'ctors.

Also, if desired, coaxial or concentric conductors may be used instead of the twisted cable. Coils 26 and 21 are connected to the ends 24 and 25 of the conductors 20 and 2|. These coils 26 and 21 arealso connected together andto the inductance. unit 28 by the wire29 for the purpose of bringing the signal energy from the antenna system to the signal receivingapparatus 33. The inductance. 28, forming the secondary of the transformer 32, is connected bywires 30and 3l to the posts A and G of the signal receivingset,

which designate the antenna and ground terminals, respectively, and should be of sufficient inductance to present a relatively high impedance to the signal frequency which it is desired to receive on the receiving apparatus 33.

The sections I0 and II of the antenna are connected to the input of the signal receiving apparatus through the electrical network 14, the conductors 20 and 2|, and the electrical network 32, such as, a transformer including primary coils 26 and 21 and secondary coils 28, as was described in the preceding paragraphs. Signal energy of frequencies corresponding, for example, to those used for broadcast purposes, intercepted by the antenna conductor sections l0 and II is impressed upon half of the windings I5 and I6 and the inductance II. An electromotive force is induced into the other half section of each of the windings I5 and I6, that is, those half sections connected to the conductors 22 and 23, from the aforesaid half sections connected to the antenna sections l0 and II and this induced potential is transmitted through the wires 20 and 2| to the coupling transformer unit housed in casing 32 including the windings 26 and 21, which are connected to the wires 20 and 2|, and the secondary winding 28 which is connected across the input circuit of the signal receiving set 33. The inductance I1 is designed to be of such value that it functions as a loading coil at the lowest frequencies, that is, the broadcast frequencies, which it is desired to received. That is, at these frequencies its impedance is relatively low and permits a relatively large current to pass, and it is of the proper value to tune the system to approximately the received frequency. Thus the antenna is more efficient as a signal pick-up or absorption member for these frequencies because this inductance tunes it thereto. This tuning may be rather broad and cover a relatively large band of frequencies depending upon the inductance and resistance and distributed capacity of the antenna conductors l0 and II.

The antenna is also rendered more efficient as a pick-up for the higher frequency signals, that is, frequencies higher than those used exclusively for broadcast purposes. The coil I1 is designed to act as a choke at frequencies higher than those at which it functions to tune the antenna. and signals of these high frequencies are caused to pass through the coils l5 and I6 down through the conductors 20 and 2| to the input transformer 32. The length of the antenna sections l0 and H is made such that the antenna may be resonant or approximately resonant to the high frequencies it is desired to receive. In this manner the antenna dimensions may be made of the proper length so that the antenna will function efficiently on a number of different frequency bands widely separated. It is also apparent that this invention is not limited to use with broadcast receivers inasmuch as it is adapted for use with any type of receiver and frequencies other than those used exclusively for broadcast reception.

The apparatus 33 also may be of any approved or conventional design using electron discharge device amplifiers and detectors and an electromagnetic device 34 for reproducing the sound at any desired loudness level. Receiving apparatus of the crystal or other detector type either with or without amplifiers also may be used if desired, with satisfactory results.

In Fig. 1a I have shown a form of this invention which I prefer to use in practicing the invention. The coupling winding I of the unit M in this case is coupled between the long antenna wire section It) and the short antenna wire section II. These sections are attached to insulators l2 and I3, respectively, as are the sections l0 and II shown in Fig. 1, and to the coupling unit housing l4, shown in Fig. 2. The end 4 of the winding is connected to the wire l0 and the end 5 is connected to the wire The purpose of this inductance winding in this embodiment of the invention, is to load the antenna inductively and make it more eflicient in the reception of long waves, such as, broadcast wave lengths and at the same time divide the antenna into two sections ID and II, enabling the use of the section for short wave reception. This section II is made of a length suitable for the eflicient reception of short waves and is connected to the electrical midpoint of the inductance winding 2 of the coupling unit l4, through the wire 3, which facilitates the use of this short section for short wave reception. Where desired, a small condenser may be connected into this wire 3, especially if the wire II is longer than necessary, but I prefer to eliminate the condenser.

An important function of the inductance is to couple the antenna to the secondary winding 2 for the reception of the longer wave signals, for example, signals now transmitted in the broadcast band of frequencies between 200 and 500 meters. Electromotive forces corresponding to the signals intercepted by the antenna are induced into the secondary 2, and cause currents corresponding thereto to flow through the conductors 2|] and 2|. These conductors 20 and 2| are connected to the ends 6 and 1, respectively, of the secondary 2 and to the winding 8, of the transformer 9 positioned adjacent or in the signal receiving apparatus.

Signal energy is impressed from the winding 8 upon the windings 9a and 9b of the transformer 9 and on the input circuit terminals A and G of the signal receiver.

In Figs. 2, 3, 4, 5, and 6 I have shown an antenna coupling unit embodying features of this invention. The antenna conductor sections I0 and I are attached to the ends of the insulation casing l4 around the ribs I41" and I43 and connections are provided between these antenna sections l0 and II and the terminals Md and Me, respectively, projecting from the housing M. An aperture is formed in the bottom of the casing M to receive the twisted conductors 20 and 2| and support same. These conductors 20 and 2| are connected to the terminals I40 and Mia which also project from the housing M, as shown in 3. On the interior of the casing I4 in a hollowed-out portion is positioned a transformer or coupling network comprising the coil windings l5, l5, and H as shown in Fig. 5. The terminals Mg and |4d are connected to the winding I5 and the terminals |4h and Me are connected to the winding l6 of the coupling network. It is, of course, obvious that the manner in which these terminals are arranged is more or less a matter of choice as long as the circuit obtained is that shown in Fig. 1.

The windings l5 and I6 are positioned between the insulation discs 35 and 36 shown in Figs. 4 and 5, and the winding H, which is connected between taps of the windings |5 and 6, is positioned between insulation discs 36 and 31. These discs may be made of fiber, phenol, or resin condensation products, wax impregnated cardboard or wood, or pressed board and. the like and they are supported together by a centrally disposed tubular rivet-like member 40 of thin metallic material or insulation. The discs 35 and 36 and tubular member 40 thus form a small spool divided in two by the disc 31, the windings I5 and I6 being placed on one side of the disc 31 and the winding I! being placed on the other. These windings may be wound directly on the spool thus formed or they may be wound first and assembled as the spool is assembled.

The windings I and 2 of the unit I4, Fig. la, are placed into the casing I4 in the same manner as the windings I5, I6, and II. The winding l is made to occupy the position of winding I5. Connections are provided between the terminals Md and Me and the coil I and similar connections are provided between the coil 2 and the terminals Mg and Hit. The connection 3 is attached tothe electrical center of coil 2 and the terminal I46.

The terminals I4d, I46, M71, and My are attached, respectively, by rivets 43, 44, 42, and 4|, for example, to the end pieces 35 and 31 of the winding spool or support, and in this way the windings, support and terminals form a unitary structure easily assembled and placed into the cavity provided therefor in the housing I4. A cover I 40 held in place by the belt Mi which fits into the hole Mk in said cover and the hole I411 in the casing, is provided for this cavity. This bolt I41, of brass or similar material adapted to resist corrosion, may be tightened to press the cap I40 tightly into the disc 39, which is of cork composition, rubber, or similar material. When the cap is pressed into this disc 39 the holes around the terminals Md and I4e, which project through the holes I41 and If, respectively, are sealed and the cap is made to fit and cover the mouth of the casing cavity in weathertight fashion. The disc 38, also of cork composition, rubber, or like material, is also pressed tightly against the terminals Mg and I4h extending out of the casing through the holes I41 and Mm, respectively, to seal any small hole that may exist around these terminals.

The casing I4 is thus made weather-proof and the coil windings protected from moisture and atmosphere. The casing I4 including the cover I40, illustrated in cross-section in Fig. 6, is preferably made of glazed porcelain which may be made readily into practically any desired shape and which is also mechanically strong and a good insulator. It is, of course, apparent that practically any plastic or ceramic materials, having good insulating properties and low moisture absorption characteristics, may be used.

While I have described a certain embodiment of this invention in detail, it is, of course, apparent that modifications within the spirit and scope of this invention may be made without departing therefrom. Therefore I do not de sire to limit this invention to the exact details described except insofar as those details may be defined by the claims.

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

1. An antenna adapted to receive signal energy of a plurality of different frequencies widely separated in the frequency spectrum comprising, an antenna conductor divided into two sections, a coupling networks connected between said two sections, said coupling network including a pair of inductance units, one of said units being connected to one of said antenna sections and the other of said units being connected to the other of said antenna sections, and .a coupling inductance connected between said pair of inductance units and adapted to load said antenna inductively at the lower frequencies to be received, and a pair of transmission conductors arranged to intercept little or substantially no effective signal or interference energy, and means for connecting said conduc tors to said pair of inductance units at points other than those to Which said coupling inductance is connected.

2. An antenna adapted to receive signal energy of a plurality of different frequencies widely separated in the frequency spectrum comprising, an antenna conductor divided into two substantially equal sections, a coupling network connected between said two sections, said coupling network including a pair of inductance units, one of said units being connected to one of said antenna sections and the other of said units being connected to the other of said antenna sections, and a coupling inductance connected between the electrical centers of said pair of inductance units and adapted to load said antenna inductively at the lower frequencies to be received, and a pair of conductors arranged to intercept little or substantially no effective signal or interference energy, said conductors being connected to said pair of inductance units and to signal receiving apparatus.

3. An antenna adapted to receive signal energy of a plurality of different frequencies widely separated in the frequency spectrum comprising, an elongated, substantially horizontal antenna conductor divided into two sections, a pair of lead-in conductors, a coupling network, said coupling network including a pair of inductance units, at least a portion of one of said inductance units being connected in series with one of said antenna sections and one of said lead-in conductors and at least a portion of the other of said units being connected in series with the other of said antenna sections, and the other of said lead-in conductors a coupling inductance connected between said pair of inductance units at points other than those to which said lead-in conductors are connected and adapted to load said antenna inductively at the lower frequencies to be received.

4,. An antenna adapted to receive signal energy of a plurality of different frequencies comprising, an antenna having at least two sections, a transformer network connected into said antenna for coupling said sections, said transformer network comprising a pair of inductances and an impedance unitconnected substantially between the electrical centers of said inductances for coupling and loading said antenna at the lower frequencies adapted to be received therewith, said impedance being adapted to act as a. choke at the higher frequencies adapted to be received with said antenna whereby said antenna is operated substantially as a doublet at said higher frequencies, and a pair of conductors connected to said pair of inductances independently for connecting said antenna to signal receiving apparatus.

SAMUEL M. WERTHEIMER.

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