The radio services Seafarer (USA) on 76 hertz and ZEVS (Russia) on 82 hertz operate in this range, which is often incorrectly called Extremely Low Frequency (ELF). They both provide communication services for submarines at a certain depth.
PCs with sound cards are increasingly being used instead of radio receivers for this frequency range, because of their much smaller size and lower cost. Signals received by the sound card with a coil or a wire antenna are analysed by a software Fast Fourier Transform algorithm and converted into audible sound.
Antennas Extend Wireless Systems; Newer Antenna Designs Are Achieving Smaller Footprints and, at the Same Time, Broader Bandwidths, as More and More Antennas Are Asked to Handle Multiple Frequency Bands
Jun 01, 2011; Byline: JACK BROWNE | Technical Contributor ANTENNAS ARE OFTEN TAKEN for granted in a system design. While they lack the elegance...