HIGH SPEED ANTENNA
Original Publication Date: 1993-Mar-01
Included in the Prior Art Database: 2002-Jan-30
Preliminary data on voice quality for digitally coded high speed, the error correcting code can compensate portable radios indicate that they lose the equivalent of for deep fades provided they only occur a small per- 4 to 8 dB when they are in a slowly moving Rayleigh centage of the time. I believe that an effective field stir- field. The radios use VSLEP coding and TDMA to com- rer could be made by putting a passive antenna element bine up to 6 voices in a 25 kHz channel. The loss occurs near the active antenna. ?he passive antenna would be because deep fades may last for several milliseconds, terminated with an electr&ically variable capacitor that which is a large part of a TDMA time slot. The tradi- could be driven with a 20 to 100 Hz sinusoidal control tional answer is a diversity system consisting of two or signal. The change in capacitance would cause the pas- more antennas. I am proposing an alternate approach sive element in the two elkment array to vary between a which in effect causes the portable to appear as ifit was directive and a reflective klement. Figure 1 shows two moving at a relatively high speed, say 30 to 60 mph. of the effective antenna patterns that could be created When the portable is moving through a Rayleigh field at by the two element array.