HF receiver antenna with programme tuner - has controlling fourpole matching circuit between antenna and main impedance transformer

摘要

TheHF receive antenna has a broadband impedence transformer coupled after the passive part of the antenna. It is made extremely small and eliminates the effects of extremely powerful unwanted transmitters. A fourpole network is connected between the passive part of the antenna and the impedance transformer. This matches the antenna output impedance to the input impedance of the impedance compared to the receiver impedance. The fourpole is tuned by programme selector. The impedance transformer may be a low-noise amplifier or a wound transformer.