High-power Electronic Tuning
Small Business Information
Green Mountain Radio Research (Currently Green Mountain Radio Research Company)
50 Vermont Ave Fort Ethan, Allen, Colchester, VT, 05446
Dr. Frederick H. Raab
AbstractTunable HF/VHF filters capable of operating at high power levels are needed for preventing a jammer from interfering with nearby friendly communications, high-speed antenna tuners, and output filters for high-efficiency power amplifiers (PAS). Filter systems presently employ either relays or pin-diode switches to select one filter from a bank of filters that spans the operating frequency range. Tuning systems similarly select combinations of inductors or capacitors. The problems with the present approach include: slow switching, especially if relays are used; size and weight; imperfect match (SWR) in band; use of inefficient class-B PAs that require no, tuning; and use of low-efficiency resistively loaded antennas. High-power electronic tuning can therefore benefit a variety of military and civilian applications. The proposed program will investigate the feasibility of high-power electronically tuned filters. The investigation includes: filter topology, semiconductors that exhibit voltage-variable capacitance, variable ceramic-chip capacitors, and variable toroidal inductors. The proposed program brings together experts on both RF-power circuits (Dr. Frederick H. Raab) and semiconductors (Dr. Krishna Shenal). Use of fewer filters makes possible reductions in size, weight, and cost. Precise tuning boosts the efficiency of RF-power amplifiers in general and makes high-efficiency (class-D, -E) amplifiers readily useable. Electronic tuning simplifies antenna tuners and makes possible the use of antennas with better gain.
* information listed above is at the time of submission.