GB675096A - Improvements in or relating to wireless aerials - Google Patents

Abstract

675,096. Aerials. MASTERADIO, Ltd. Feb. 14, 1950 [Feb. 14, 1949], No. 3962/49. Class 40 (vii). A short-wave aerial comprises a length of the usual flexible lead connecting a receiver to the wiring system of a building, means for isolating the said length from the system at the radio frequency concerned by the introduction of a sudden change in the inductance or self-capacity in the lead, and means for transferring the voltage or current at the receiver end of the length to the first stage of the receiver. The length of lead chosen to constitute the aerial is arranged to be a quarter wavelength long or a multiple thereof. If the length is one quarter wave length or an odd multiple thereof there is a current maximum at the receiver end of the aerial and an " earth " must be provided. As there are two wires in the flexible supply lead the primary of the aerial coupling transformer 8 must be bifilar, the two wires being extended as at 9 to provide the operating power for the set. Condensers 10 between each wire and earth provide the earth connection. The sudden change in the mains lead isolating the aerial section may be provided by kinking the wire, close coiling it for a short length or by the use of a collar of highly permeable or high dielectric constant material fixed round it, or by a combination of these means. It is stated that by putting alternate collars of dielectric material and permeable material along a relatively short part of the mains lead a broad band effect is obtained and also that two or more fairly widely separated frequencies may be handled by the use of a similar number of suitably positioned discontinuities. Specification 598,165 is referred to.