Abstract: An RF input tuning circuit in a UHF electronic tuner uses a semicoaxial resonant cavity circuit which feeds amplifier and other tuning circuits not of the semicoaxial type, such as lumped constant or strip-line types.

Abstract: To minimize overmodulation in an active window antenna and radio receiver system, an amplification control voltage is produced in the active antenna, i.e., directly behind the antenna pre-amplifier, and is used to control the amplification of the pre-amplifier.

Abstract: An electrical frequency responsive circuit comprising a first coil constructed of wire having an insulating coating thereon wound in a single layer about an axis of generation, and a second coil, also constructed of wire having an insulating coating thereon wound about an axis of generation in a single layer, said coils being axially related and having diameters and/or pitch to provide inductance and capacitance between the coils which is at least initially adjustable whereby the circuit is responsive to an electric signal having a predetermined electrical frequency imposed across the coils to provide frequency band suppression about the predetermined frequency.

Abstract: The front end circuit is constituted by first and second signal paths for transmitting a high frequency signal received by an antenna, and a transfer switch for selecting either one of the signal paths depending upon the state of the received signal, and a circuit for converting the frequency of either one of the selected signals to an intermediate frequency signal. Two signal paths have different filtering attenuating and amplifying characteristics, thereby providing an optimum condition for either a local or distant reception of radio wave signals.