GB653876A - Improvements in and relating to short-wave aerials - Google Patents

Abstract

653,876. Aerial coupling arrangements. BEST, N. M., and ANTIFERENCE, Ltd. Aug. 11, 1948, No. 21173. [Classes 40 (v) and 40 (vii)] A dipole aerial system comprises an inductive loading in each arm of the dipole and an inductively-loaded matching stub connected thereto as shown either in Fig. 4 or Fig. 5. In Fig. 4, the dipole is connected to a receiver 13 and stub wires 25 and 26 are connected to the inner ends of the dipole. The stub wires each consist of brass tape and are separated by a polythene film, a portion of the length of each wire being coiled. In Fig. 5, the dipole comprises arms 27 and 28, the element 27 serving also as one of the stub wires, the other stub wire being shown at 29. In order to match the aerial system of Fig. 5, the impedance of which is approximately 20 ohms, to the receiver 13, a 50 ohm resistor is preferably connected in the lead to the receiver. Means may be provided for switching the resistor out of the circuit when it is desired to obtain as large a signal as possible. Fig. 9 shows a practical embodiment of the system illustrated in Fig. 5. This arrangement comprises two aluminium tubes 32 and 33 of semi-circular section, separated by a film of polythene 34. The tubes 32, 33 are short-circuited at 35 by a member which is made adjustable for tuning the stub. The tubes 32 and 33 are connected to brass strips 36 and 37 which are coiled upon the former 38 and insulated from one another by a polythene film. The aerial also comprises an aluminium tube 39 connected to a brass-tape coil 40 wound upon the former 38.