Design, Implementation and Test of a Wideband HF Receiving Subsystem

The High-Frequency (HF) band has increased in popularity in recent years. Present receive subsystem designs are capable of covering the entire band, and are often engineered to be collocated with HF transmitters. Because of the high levels of atmospheric and galactic noise encountered in the HF band, proper receive subsystem design does not attempt to provide minimum noise figure as is the case at UHF and SHF. Rather a tradeoff is attempted between external noise and subsystem noise. Ideally the receive subsystem is external noise limited, but just barely so. This paper considers that tradeoff, discusses system noise figure with a mismatched receive antenna, and also discusses the design of a receive subsystem.