GB1008210A - Improvements in and connected with television receiving antennae - Google Patents

Abstract

1,008,210. Aerials; transistor tuned amplifiers. AUSTENNA PROPRIETARY Ltd. May 22, 1962 [June 9, 1961], No. 19683/62. Headings H3T and H4A. An indoor television aerial assembly comprises an aerial mounted on a hollow tubular base containing a transistorized amplifier the input impedance of which is matched to the aerial impedance, the amplifier being tuned to cover at least one television channel. In the embodiment illustrated, aerial 2 comprises arms 20 fitted into a hollow portion 19 of a member 17 having a socket 18 passing over a ball 16 on a plug member 14 fitted to the upper end of a sleeve 12. The sleeve is fitted at its lower end into a base 5 which carries legs 7; lugs 8 are provided to hold the legs stable. A conductive helix 21 is wound about, and insulated from, the aerial. A transistorized amplifier is fitted within sleeve 12 and its circuit is shown in Fig. 3; the base of transistor T is " floating," to maintain aerial balance, a matching circuit comprises inductors L1, L2, L3 and capacitor C1, coupling capacitors C2, C3 prevent D.C. passing to the aerial, and the D.C. operating conditions for the transistor are set by resistors R1, R2, R3. Choke RC1 isolates R.F. currents. The collector load consists of two tuned circuits: one, comprising inductor L6 and capacitor C6, is for lower-frequency channels and the other, comprising inductor L4 and its self-capacitance, is for higher-frequency channels. Output coupling is effected by coils L7, L5 and associated capacitors C7, C8. Chokes RC2, RC3 block signal currents. Diode D protects the transistor should D.C. of incorrect polarity be applied to the circuit. The power supply may be a battery or be derived from the associated receiver. Alternative aerials are conductive elements spaced from each other and adjustable both in length and angle, a conducting loop, and a ferrite rod having at least one coil wound thereon.