Tim wrote: > Not a radio guy, but have noticed that some use a second antenna, so > matching to a radio/transponder (?) is not as critical, as the 'splash > back' (returning energy ) is reduced by the extra antenna......Correct or > Somewhat Correct? > > CldLk-Tim > INCORRECT. If two antennas are found there must be either an impedance matching device between the transponder and the paralleled antennas (not a common practice) or the transponder will have an internal sensing circuit which will switch to the antenna with the strongest received signal automatically (accepted practice). This type of unit normally has two antenna outputs on the rear or one antenna output and an external switching unit with 3 RF connectors (Ant 1, Ant 2, RF to/from transponder). in addition it will have an antenna select control signal wire connected between it and the transponder by which the circuits in the transponder will select the antenna with the strongest received signal. Any other arrangement is incorrect and will damage the transponder transmitting section as well as produce poor reception.
-- Glenn Martin KR2 N1333A 13238 Hudson-Krohn Rd. Biloxi, MS, 39532 rep...@martekmississippi.com
