GB748001A - Improvements in or relating to aerials for multi-band radio receivers - Google Patents

Abstract

748,001. Aerials. TELEFUNKEN GES., [formerly TELEFUNKEN GES. FUR DRAHTLOSE TELEGRAPHIE], Oct. 15, 1954 [Oct. 17, 1953], No. 29710/54. Class 40 (7). An aerial for a multi-waveband radio receiver comprises a rod R of magnetic material carrying a coil for the reception of signals in one waveband and a supplementary coil for the reception of signals in a longer waveband, wherein the coil for the shorter waveband is arranged to extend over a greater portion of the rod length than is the supplementary coil. Preferably each of the coils is sub-divided into two portions; the elongated winding M1 and short movable winding M2 forming the shorter waveband coil and the windings L1 and L2 forming the supplementary coil. The latter may be short-circuited by a switch S when not required or it may be completely disconnected or placed in parallel with the coil M1, M2. The inductances of the coils may be adjusted by moving the outer portions L2, M2, relative to the inner portions and so changing the mutual inductance. Movement of the outer portion of one coil does not substantially affect the inductance of the other coil. As shown, practically the whole length of the rod is used for longer waveband reception and about <SP>3</SP>/ 6 th of it for reception in the shorter band. The winding M1 need not be elongated as shown, but may be the same as winding M2 and spaced from the latter so that the whole coil extends over a large proportion of the rod length (Fig. 2, not shown). The invention can be applied to aerials for reception on three different wavebands.