US2021734A

US2021734A - Transmission line network for radio receiving antennae

Info

Publication number: US2021734A
Application number: US611376A
Authority: US
Inventors: William W Macalpine
Original assignee: International Communications Laboratories Inc
Current assignee: International Communications Laboratories Inc
Priority date: 1932-05-14
Filing date: 1932-05-14
Publication date: 1935-11-19
Anticipated expiration: 1952-11-19
Also published as: BE392535A; FR746441A; GB415687A

Description

NOV. 19, 1935. w w c m 2,021,734

TRANSMISSION LINE NETWORK-FOR RADIO RECEIVING ANTENN/E Filed May 14, 1932 23 FIG. I 28 J II I INVENTOR WILLIAM W. MACALPINE ATTORNE Patented Nov. 19, 1935 UNITED .STATES PATENT. or-Pics amass D10 RECEIVING WllIiamW.llacalpino,East0n-nge.

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New York The present invention relates to transmission lines and networks for interconnecting radio receivers and the antenna: supplying energy thereto.-

At the present time the receiving antenna for a radio receiver is placed as near the receiver as is plrvsicallypossible. This in many instances means that the antenna. is placed in a location where the level of interfering signals is high and the reception consequently poor. This invention makes it possible to locate the antenna at a point remote from the radio receiver and to transmit the signals received on that antenna to the receiver without picking up extraneous noise.

One of the objects of this invention is the provision of means whereby an antenna may be located ata point remote from the receiver in a location where interfering signals are not pres-'- ent or are present to only a slight degree.

Another object of the invention is to transmit,

received signals from a receiving antenna to a remote radio receiver without appreciable distortion.

A further object of the invention is to provide means whereby the input energy supplied to a receiver from a remote antenna is substantially unchanged in amount regardless of the frequency of the signals to which the receiver is tuned.

Further objects of the invention will appear from the following description taken in connection with the drawing.

In the drawing:

Fig. 1 shows the antenna, transformer network, transmission line and receiver, particularly designed and adapted for reception of signals in the broadcast range, that is to say signals of frequencies ranging from 600 to 1800 kilocycles.

Fig. 2 is similar to Fig. 1 except that the transformer network is adapted to thereception of signals in the short wave band, that is frequencies from 1.5 to 20 megacycles.

Fig. 3 shows an arrangement for operation over a wider frequency hand than the arrangement of Figs. 1 and 2. I

Fig. 4 shows a modified arrangement of the receiver input transformers adapted to feed two receivers from a single transmission line when those receivers are operating over different frequency ranges.

Fig. 5 shows an arrangement for operating a number of receivers from the same tron line and antenna.

7 Referring to Fig'. 1 the receiving antenna designated HI, has in series herewith the two tuned circuits II and lljcrmnected inseries opposition between the antenna and ground. Tuned circuit ll comprises an inductance coil It and condenser i4 and similarly, tuned circuit i2 comprises the coil II and condenser-ll.- Coils I3 and I! are closely coupled and form the primaries of a transformer network, the secondarim ,of which are designated, respectively, I! and 20; Tunedcircuit II is tuned to a frequency near the upper end and within the broadcast band. that is to a frequency of about 1500 kilocycles.

Tuned circuit l2 has a resonant frequency near the lower end of and within the broadcast band,

that is about 600 kilocycles. The coils I9 and to the transmission line 2|. The capacity shield 22 is inserted between the primaries and sec- 1 ondaries of thecoils and is grounded at 23. It

is apparent from the above that there is close 20 coupling between primary l8. and secondary l9 and between primary l1 and secondary 20. Sec- 7 ondary II is smaller than secondary 20, and this together with the fact that condenser 24 is in series with secondary i9, serves to prevent the g shortcircuiting of coil 20 at the low frequencies,

while at the high frequencies, coil 20 being larger has little effect on signals in coil i9. At frequencies between the resonant peaks mentioned, namely 1500 and 600 kilocycles, and to some 30 extent at all frequencies, energy is transferred from the antenna to the line through both l3l9 and "-20. It is to be noted that while coils l3 and II are connected in'series opposition, coils I9 and 20 are connected in parallel aiding 5 relation.

The transmission line, designated 2|, connects to the secondaries i9 and -20 and extends to the desired position of the radio receiver at which point it terminates in the primary 26 of 'trans- 40 former 25. The center points of secondary 20 and of primary 26 are connected to ground to equalize and cancel out extraneous capacitive and inductive effects on the line. The transformer 25 has a capacity shield 28 between its 45 windings 26 and 21. Secondary winding 21 is connected to the signal input circuit of the receiver. The transformer design is such that the impedance of the receiver matches the impedance of the line, the receiver impedance considered tocoil II and coil ll tocoil 20. Inpractice this close coupling is accomplished, in the case of coils l3 and l9, l1 and II by winding coils l8 and 2| side by side upon the same form after which a sheet of foil shielding material is wrapped about these coils, the foil being insulated by suitable paper insulation in a well known manner. Coils II and I! are then wound above their respective secondaries I! and 2.. Transformer 2! is constructed in the same manner, this transformer however having but two coils 2i and 21, wound one above the other with paper and foil between.

The constants of the transformer network are so chosen that the input to the receiver is substantially the same at all frequencies. The mode of connecting coils i3, i1, is and III is such that the currents in the transmission line are additive in phase. This serves to eliminate the regions of very low energy transfer which would occur if the currents were out of phase.

Fig. 2 shows an arrangement for shortwave operation. In this instance it has been found unnecessary to supply two secondary windings. Hence the secondaries is and 20 of Fig. 1 are replaced by a single center tapped secondary 30. Condenser 29 may be omitted in this arrangement, since at these high frequencies the capacity of the antenna to ground shown in dotted lines -at 32 suffices, together with coil 33, to form a resonant circuit at the higher frequencies of the band. The operation of this circuit is exactly similar to that described above in connection with Fig. 1.

Fig. 3 shows an alternative transformer network for covering a wider frequency band than that for which the above described arrangements are suitable. In this arrangement there are three tuned circuits one of which is tuned to a frequency near the upper limit of the band to be received, the second to a frequency near the middle of the band and the third to a frequency near the lower limit of the band. The receiver input transformer may be of the form described in connection with Figs. 1 and 2 or of the alternative form described below. The condenser to tune the high frequency coil may be omitted in some cases.

Fig. 4 shows an alternative arrangement of the transmission line and receiver input transform-v ers. This arrangement is adapted for use when the two receivers are operating on different frequency bands. It comprises two transformer primaries connected in parallel to the line, with a blocking condenser connected in series with one winding of one of the transformers. This condenser servos mainly to prevent this transformer primary, whichis adapted to transmit high frequencies, from acting-as a short circuit around the other parallel transformer primary.

Fig. 5 shows a transmission line along which several receiving sets are located. These receiving sets are connected to the transmission line by transformers similar in every respect to transformer of Fig. 1. In this case it is however desirable that the resultant of the impedances of the several receiving sets be approximately equal to the line impedance.

The transmission line proper may be of any one of several forms as twisted pair wire, sheathed wires, 9. transposed pair or in some cases parallel open wires. The particular form of the transmission line forms no'part of the invention and is shown merely for clarity.

The foregoing is given for the purpose of descriptiononly,andisinnowaytolimittlie scope of the appended claims.

What is claimed is:

1. In a on line system for frequencies within a band of frequencies, an antenna, 5

a radio receiver, a pair of transformer primary windings in series opposing relation connected to said antenna to receive energy therefrom, a tuning condenser in shunt to each primary winding whereby the windings are tuned to different freo quencies within said band, secondary windings inductively coupled to said primary windings, a transmission line connected to said secondary windings to receive energy of all frequencies within said band, and means for coupling said trans- 15 mission line to said radio receiver.

2. In a transmission line system for frequencies within a band of frequencies, an antenna, a radio receiver, a pair of transformer windings in series opposing relationship connected to said go antenna to receive energy therefrom, a tuning condenser in shunt to each of said windings whereby the windings are tuned to different frequencies within said band, a secondary winding coupled to said first mentioned windings to re- 25 ceive therefrom energy of all frequencies within said band, a transmission line connected to said secondary winding, and means for coupling said transmission line to said radio receiver.

3. In a transmission line system for frequencies within a band of frequencies, a receiving antenna, a transmission line receiving energy therefrom, a doubly resonant circuit connected in series with said antenna and comprising trans-- former primary windings connected in series opposing relation, said windings being tuned to different frequencies within said band, and means for transferring energy of all frequencies within said band from said doubly resonant circuit to said transmission line, said means comprising 40 transformer secondary windings connected in parallel aiding relationship.

4. A receiving system for frequencies within the broadcast range comprising a radio broadcast receiver, an antenna for supplying energy thereto, a transmission line coupled to said radio receiver, means for matching the impedance of said receiver with the impedance of said line, a circuit resonant to a frequency near the upper and to a frequency near the lower limit of the broadcast range connected to said antenna, said circuit containing two inductances in opposing relation, and means for coupling said resonant circuit to said transmission line so as to transfer thereto energy of all frequencies within said band. 5

5. A receiving system for frequencies within a band of frequencies comprising a radio receiver, impedance matching means, a transmission line coupled to said radio receiver thru said impedance matching means, a tuned network 0 coupled to said transmission line and comprising a plurality of transformer windings each connected in series opposing relationship to the preceding windings, the windings being tuned to different frequencies within said band, whereby 5 energy of all frequencies within said band is transferred to said transmission line and an antenna circuit connected with said network.

6. A receiving system for frequencies within a band of frequencies comprising a receiving an- 7 tenna circuit, a plurality of tuned oscillation circuits having coupled inductances in seriesopposing relation connected in said antenna circuit, said oscillation circuits being tuned to different frequencies within said band, a transmission line,

and means comprising secondary inductances connected to said line in parallel aiding relationship to each other for transferring energy of all frequencies within said band from said tuned circuit inductances to said line.

7. A transformer network for interconnecting a receiving antenna and a transmission line comprising a pair of opposed inductances connected in series with said antenna, means to tune one of said inductances to a frequency near the upper end of a band of frequencies to be received, means to tune the other of said inductances to a frequency near the lowerend of a band of frequencies to be received, and a plurality of means connected in parallel for coupling said inductances to said transmission line so as to transmit thereto energy of all frequencies within said band.

8. A transformer network for interconnecting a receiving antenna and a transmission line comprising a pair of opposed inductances connected in series with said antenna, means to time one of said inductances to a frequency near the upper end of a band of frequencies to be received, means to tune the other of said induetances to a frequency near the lower end of a band of frequencies to be received, and means for coupling said inductances to said transmission line.

said primary windings to receive therefrom energy of all frequencies within a band including said different frequencies, means for connecting said secondary windings in parallel to said transmission line, and a condenser in series with one of said secondary windings only.

10. A network for coupling an antenna circuit to a transmission line and comprising a plurality of tuned oscillation circuits having coupled inductances in series opposing relation for connection to said antenna circuit, each oscillation circuit being tuned to a different frequency within a band of frequencies and one of said oscillation circuits being tuned to a frequency near the upper limit and another to a frequency near the lower limit of said band, and means comprising secondary inductances connectable to said line in parallel aiding relationship to each other for transferring energy of all frequencies within said band from said tuned circuit inductances to said line.

11. A network for coupling an antenna circuit to a ton line comprising a plurality of tuned oscillation circuits having coupled inductances in series opposing relation for connection to said antenna circuit, each oscillation circuit being tuned to a different frequency within a band of frequencies and one of said oscillation 5 circuits being tuned to a frequency near the upper limit and another to a frequency near the lower limit of said band, and means comprising a secondary inductance coupled to said tuned oscillation circuits to 'receive therefrom energy of all frequencies within said band and connectable to said transmission line to transfer said energy thereto.

12. A network for coupling an antenna circuit 1 to a transmission line comprising two tuned oscillation circuits having coupled inductances in opposing relation for connection to said antenna circuit, one oscillation circuit being tuned to a A frequency near the upper limit of a band of frequencies to be received and the other being tuned to a frequency near the lower limit of said band, and a secondary-inductance coupled to said oscillation circuit inductances to receive therefrom energy of all frequencies within said band and connectable to said transmission line for trans-- ferring said energy thereto.

13. A network for coupling an antenna circuit to a transmission line comprising two tuned oscillation circuits having coupled inductances in opposing relation for connection to said antenna circuit, one oscillation circuit being tuned to a frequency near the upper limit of a band of frequencies to be received and the other being tuned to a frequency near the lower limit of said band, and two secondary inductances coupled to 85 said oscillation circuit inductances to receive therefrom energy of all frequencis within said band, said secondary inductances being connectable in parallel aiding relationship to said transmission line, one of said secondary inductances being smaller than the other, and a condenser connected in series with the smaller of said secondary inductances.

14. A network for coupling an antenna circuit to a transmission line so as to transfer from the former to the latter energy of all frequencies within a band of frequencies and comprising a plurality of tuned oscillation circuits having coupled inductances connected in opposing relation in said antenna circuit, each oscillation circuit being tuned to a different frequency within said band and one of said oscillation circuits being tuned to a frequency near the upper limit and another thereof to a frequency near the lower limit of saidband, and a secondary inductance coupled to said oscillation circuit inductances and connectable to said transmission line.

WILLIAM W. MACALPINE.