Accession Number : ADA118861

Title :   Improved Airborne HF Receive Antenna - An ILIR Report - FY-81.

Descriptive Note : Technical rept.,


Personal Author(s) : Brune,John F ; Gratalo,John G

PDF Url : ADA118861

Report Date : Jul 1982

Pagination or Media Count : 46

Abstract : An investigation of improvement of signal-to-noise ratio in an Airborne High Frequency Single Sideband (HF SSB) system by use of an 'active', dedicated, receive antenna function, in addition to a combination transmit/receive mode now commonly provided (shorted-loop). The approach described is an optional receive mode of the shorted-loop antenna, where electronic tuning, a stage of RF gain and a stage of matching is provided in lieu of passive tuned function normally provided by the HF SSB amp/coupler. The results obtained in this study show a possible improvement of 5 to 10 dB in the signal-to-noise ratio over the passively tuned antenna. This translates in raising an intelligibility reading of a 2 to 5. It is anticipated that this improved sensitivity can provide a doubling of the width of the 'window' in some cases. A second advantage is to permit very rapid scanning over a broad range of frequencies within a portion of the 2-30 MHz HF Band while using a 'High Q' device. The present shorted-loop design is passively tuned by cumbersome mechanically driven capacitors, thus preventing a rapid receive scan mode. (Author)

Descriptors :   *Aircraft antennas, *Loop antennas, *Radio equipment, *Tuning devices, *Helicopters, Signal to noise ratio, Single sideband communications, High frequency, Impedance matching, Electronic equipment, Antenna feeds, Width, Functions, Radio receivers, Windows, Avionics, Intelligibility, Gain, Reading, Capacitors, Antennas, Airborne

Subject Categories : Helicopters
      Electrical and Electronic Equipment
      Radio Communications

Distribution Statement : APPROVED FOR PUBLIC RELEASE