Merge two transceiver on a single antenna

[mcdesca]

Hello everybody,

I have two 2.4Ghz transceivers transmitting and receiving from their own antenna on separate channels, and would like to know if it is possible to merge both on a single antenna.

I have seen "splitters/combiners" and "diplexers", but I don't know how effective they are. There are tons of cheap splitters/combiners, but no diplexers.

I have seen that a splitter/combiner just splits the power (dangerous for the transceiver?), whereas a diplexer filters different channels on each output.

Which direction do you recommend me to follow?


Thanks a lot.

[PA0PBZ]

You'd need 2 very sharp bandpass filters to do this, and since WiFi channels do overlap you also need to put them on channels that are quite separate from each other.
But generally I'd say it's not worth the effort, doing this is like 50 times as complex (and costly) as just using 2 antennas.

[thewyliestcoyote]

If the 2 radios are not trying to transmit and receive or transmitting and transmitting at the same you could just use a RF switch network. You will most likely take a 3 to 6 dB hit in the Rx sensitivity and the resulting network will be more trouble than a second antenna. You have not mentioned the application but I am going to awesome (maybe wrongly so) you are using printed or chip antennas. I.e. Cheaper than what is required to make than operate. Again I am making some assumptions here like this is not to do full duplex, antenna limited systems, very size limited, and so on.

Little note on odd numbered of port devices, they can be lossless, perfectly matched, and reciprocity. But they can only be 2 of those 2. If one device is transmitting and one is receiving you can use a device called a circulator. The are not cheap and are big.

http://www.microwaves101.com/encyclopedias/circulators

If you could provide a little more information about the application we maybe more able to help.

Best,
Wylie

[mcdesca]

Hello and thanks for the responses,

The goal is to study the feasability of eliminating one antenna, I am already taking into account that that is complex.

I am using two CC2500 from TI in separate channels, doing TX/RX (half duplex, internally controlled), with a 200mW amplifier downstream on each channel. I think they are used in ZigBee, 802.15.4, R/C toys and small area network architectures. The antennas are standard 5-6dBi RPSMA omnidirectional like those installed on AP's.

They could indeed transmit and receive at the same time. The TX will be amplified on both ends. And for the application, it is more feasible to install amplifiers than another antenna.

@thewyliestcoyote: What do you mean by "odd numbered of port devices", would you please explain that?

Many thanks.

[Christe4nM]

This video of W2AEW came to mind:


I suppose you could use it with two tranceivers as well? That said I have no meaningfull RF knowledge, so maybe others can tell you whether modifying this circuit to suit your needs is feasible at all.