Variable reactance type active receiver aerial - uses two electronic reactance elements kept at equal ambient temp. to facilitate tuning tracking of aerial and oscillator

摘要

The active reception aerial comprises an electronic reactance arranged across the output of a passive aerial. The impedance of the reactance is voltage-controlled to provide resonance at the input circuit of a transistor amplifier. Exact tracking of aerial and oscillator tuning is achieved so as to allow single-dial control. - A mixer stage (U2,T3) is connected to the oscillator (U3, C2, T2) at the output of the amplifier and the frequency setting circuit of the oscillator is provided with a second electronic reactance (D2). The latter's impedance can be varied via a d.c. voltage (UR). Both electronic reactances D1,D2) have, at the same temp., approx. equal reactance characteristics; thus devices are provided to provide the reactances (D1,D2) with approx. the same ambient temp. PS(1/4)