Coaxial LC phase-shifter for phase-controlled television broadcast switching circuit

摘要: A television broadcast transmitter includes two power amplifiers or transmitters, a dummy load and an antenna. noncontacting switching arrangement directional couplers hybrids operated as controllable phase-shifters under the control of pairs variable reactive terminations. Signals arriving at antenna port by paths combine in-phase to couple signal that port, out-of-phase cancel signal. If condition is inaccurate, cancellation may be incomplete, resulting in crosstalk. To avoid need for accurate positioners position termination providing desired phase-shift, particular structure used. The short-circuited coaxial line with axial gap center conductor less than one quarter operating frequency wavelength from short circuit. hollow around lined insulating material, elongated conductive slug actuated selectively occupy positions within conductor, remote whereby minimum series capacitance results, second straddling gap, increases. rod passing through rate change phase-shift function actuator small near extremes actuation positions, errors do not affect phase-shift.