US2229949A - Radio aerial installation - Google Patents

Description

Jan. 28, 1941. N. WELLS RADI O AERIAL INSTALLATIQN Filed Jan. 21, 19159 {X y INVENTOR GW NORMAN WELLS BY /g ATTORNEY Patented Jan. 28, 1941 PATENT OFFICE RADIO AERIAL INSTALLATION Norman Wells, Epsom Downs, England, assignor to Radio Corporation of America, a corporation of Delaware ApplicatiDn January 21, 1939, Serial No. 252,130 In Great Britain January 22, 1938 6 Claims.

This invention relates to aerial installations and has for its object to provide improved installations suitable for use where the aerial height is limited and where the transmitting and/or receiving apparatus associated with the aerial is required to be installed well above ground level.

In many cases, notably in airport radio stations, the permissible height of a radio aerial is 10 relatively low, and, moreover, the associated radio apparatus is often required to be installed on an upper floor of the airport buildings. In known installations such conditions involve the use of a long earth lead and low efiiciency generally. The present invention seeks to improve the efficiency of radio installations required to be installed in adverse circumstances such as those just mentioned.

According to this invention a radio aerial installation comprises an aerial capacity carried approximately horizontally at the maximum allowable height above ground; a two conductor feeder, the conductors of which are so arranged that the net radiation from the feeder as a whole is zero or nearly so; a connection between the aerial capacity and one conductor of the feeder at one end thereof; and an active aerial consisting of a down conductor connected between earth and the other conductor of the feeder at the said end thereof, the two feeder conductors being arranged for connection, at the other end of the feeder, to the transmitting or receiving apparatus, as the case may be.

The invention is illustrated in the accompanying drawing in which Figure 1 shows an embodiment and Figure 2 another embodiment.

Referring to Figure 1 which shows one way of carrying out the invention, an aerial capacity which may consist, in the simplest case, of a single wire, but normally will be a twin wire or three wire capacity top suspended horizontally at the maximum allowable height, by means of any convenient arrangement of masts. In Figure 1 this is a three wire top T suspended between masts M1 and M2. This aerial capacity is connected to its associated receiving or transmitting apparatus-installed, for example, on an upper floor of a building B-by means of a feeder which consists of two parallel conductors F1, F2

run close together and, for example, one above the other as shown. One end of the upper conductor F1 is directly connected by connector C to the middle of the aerial capacity and is suspended thereby, while the corresponding end of the lower conductors F2 is suspended from the middle of the aerial capacity by means of a suitable in sulator I and is connected to the upper end of a vertical down lead DL which constitutes the active aerial and whose lower end is directly earthed in the usual manner, e. g. by means of 5 a radial or other pattern of ground wires GW or the like. The other ends of the feeder wires F1, F2 are brought to lead-in insulators L1, L2 on the building-this should preferably be at least 20 metres distant from the active aerial 10 or down lead DLand from these insulators connection is made to a suitable coupling coil or coupling circuit (not shown) associated with the transmitter or receiver, (not shown) as the case may be. Other insulators I are provided as re- 15 quired between F1 and F2.

In the modification shown in Figure 2 a mast or tower DL' serves the same purpose as the down lead DL of Figure 1--i. e. acts as the aerial proper-and is provided with a capacity top T 20 carried from the mastradiator by insulators I" on arms A. One feeder wire F1 is connected to the top T and the other on the upper end of the mast-radiator.

These arrangements have the merit of making 25 substantially the whole height effective since it converts what would otherwise be a long earth lead, taking away from the effective height of the aerial, into the active radiator. Since currents in the twin feeder wires F1, F2 are substan- 30 tially equal and opposite, the length of feeder between aerial and building is substantially nonradiating and, therefore, substantially will not set up undesired counter-phase effects.

Having now particularly described and ascer- 35 tained the nature of my said invention and in what manner the same is to be performed, I declare that what I claim is:

1. Aradio aerial installation comprising an aerial capacity carried approximately horizon- 4o tally at the maximum allowable height above ground; a two conductor feeder the conductors of which are so arranged that the net radiation from the feeder as a whole is substantially zero;

a connection between the aerial capacity and 5 one conductor of the feeder at one end thereof; and an active aerial consisting of a down conductor connected between earth and the other conductor of the feeder at the said end thereof, the two feeder conductors being arranged for 50 connection, at the other end of the feeder, to the transmitting or receiving apparatus.

2. An installation as claimed in claim 1 wherein the capacity top is suspended horizontally and the down conductor is carried vertically between 55 substantially the middle thereof and a pattern of ground wires, or the like, being insulated from said top.

3. An installation as claimed in claim 1 wherein the capacity top is carried at and insulated from the top of a mast which acts as the down conductor and is connected at its lower end to a pattern of ground wires or the like.

4. A radio aerial comprising a vertical radiating member grounded at its lower end and nonradiating feeder means for energizing said member coupled to its upper end.

5. A radio aerial comprising a vertical radiating member grounded at its lower end and means for energizing said member at its upper end, said means including a two conductor non-radiating feeder having one conductor connected to said member and the other connected to a horizontal capacity member.

6. A radio aerial comprising a vertical radiating member grounded at its lower end and means for energizing said member at its upper end, said means including .a non-radiating two conductor feeder having one conductor connected to said member and the other conductor connected to a horizontal capacity member closely adjacent the upper end of said antenna.

NORMAN WELLS.

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