Bandwidth Efficient Synchronous Tuning (BEST) for Improved Very-Low-Frequency and Low-Frequency (VLF/LF) Communications.

摘要

Synchronously tuning a transmit antenna to the instantaneous tones of a frequency modulated waveform can result in enormous improvements in radiated power efficiency and data detection. The best performance is obtained when the modulation waveform tones are phase continuous and when the maximum tone separation is much smaller than the operating frequency. Both of these conditions are satisfied by most systems. The advantages in using Bandwidth Efficient Synchronous Tuning (BEST) are realized by a significant reduction in the loss and distortion affects usually associated with fixed tuned antennas. This paper characterizes the performance of continuous-phase frequency-shift-keying (FSK) and minimum-shift-keying (MSK) modulated waveforms with synchronous tuning of the transmit antenna. Analysis and computer simulation results support the conclusion that there is less than 0.5 dB degradation in the bit-error-probability performance for instantaneous antenna bandwidths(B) several orders of magnitude less than the modulation bandwidth (1/T). Also, the radiated power can be increased by as much as 7 dB, for time-bandwidth (BT) products as low as 0.3, through the elimination of the flat loss and amplitude distortion usually associated with fixed tuned antennas. Reprints. (RRH)