A small relay with low series inductance is probably the easiest, next
choice would be
a pin diode.  Coaxial relays are expensive. (Depends on your application.)

If you use a relay then the normally closed contact would be the receive side.

Some extra hints, if you are connecting to an external antenna, put some
thought
into lightning protection. Transient suppression and a resistor to ground.


>
>Just casting about for ideas here ....
>
>I want to build an Rx/Tx master/slave system using a PIC, 16F84
>probably, and a pair of RF Rx/Tx modules that are available these
>days. But it seems grossly inelegant to use two aerials for separate
>channels.
>
>One idea that occurred to me was :-
>
>
>\|/ Aerial
> |________________|Switch|_____|Rx    |_______|Decoder|____|   |
>                  |      |     |module|       |145026?|    |   |
>                  --------                                 |PIC|
>                      |________|Tx    |_______|Encoder|____|   |
>                               |module|       |145027?|    |   |
>
>OK, the switch would have to pass a VHF signal in either direction,
>depending on whether the PIC was sending or receiving. You'd only get
>half-duplex with this arrangement, but that's OK. You'd be
>sending\receiving binary data, not analogue but that's also OK. You
>MUST keep the Rx module's input isolated when the Tx module is Tx-ing.
>Obviously. You'd control the switch with a PORTA pin, probably.
>
>So what about the RF switch? Any ideas for that come to mind?
>
>Many thanks for ideas!
>
>Regards - Ian Hynes
>
>PS: May I wish PICers everywhere all the best for the New Year?
>
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>
>
>

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