SImple switch to swap inputs and outputs

Question

I can't see this exact question answered elsewhere, so here goes...

I want to build an antenna switch that'll allow me to SWAP two antennas between two antenna sockets on the radio. Common Ground, by the way... STATE 1 - Antenna A to input A and Antenna B to input B STATE 2 - Antenna A to input B and Antenna B to input A

I'm sure there's a very simple diagram to solve this but I can't get my head around it! I may just use a passive switch or possibly use a relay if there are too many losses in a switch.

Thanks very much.

Answer 1

Is it this arrangement you're looking for? You need a DPDT switch or relay. Whether this works for your signals is a different matter, and there can be a lot of issues for antennas.

^{simulate this circuit – Schematic created using CircuitLab}

Answer 2

Low voltage RF signal switching is not like other low power circuits. Mismatched wire/transmission line impedances, stray capacitances, and connector characteristics can combine for significant signal degradation. Switches and relays that are purpose-built for RF switching are relatively expensive, but perform much better.

Ham radio websites have lotsa information about this, links to vendors, etc.

Because pc boards are so cheap these days, one approach is to use a small DPDT relay on a pc board with stripline or micro-stripline path routing and standard RF connectors. This can reduce most of the impedance and shielding issues.

What signal frequencies are you switching?

Update:

The original question mentioned a radio, but not a transceiver. For that, there are many RF and antenna switch boxes on ebay. Two SPDT units mechanically ganged together will give you the DPDT function you want.