RF Switches

[yanir]

Hi, for the RF gurus out there:
I'd like to share a single 2.4Ghz antenna between two RF transceiver IC's (Wifi, and BLE). I only need one operating at a time and can handle graceful handover in software.

My question is:
Can I use an RF switch like this to switch the antenna path from one to the other?:
http://www.mouser.com/ds/2/249/MASWSS0115-318361.pdf

I assume this part is bidirectional and would work, but after reading the datasheet I wasn't totally sure. If this is not the correct part, any recommendations would be greatly appreciated. Also, if you think this is a terrible idea, please tell me. I'm not an RF engineer, but I have done successful layouts for RF IC's including basic (app note guided) antenna layout.

Thanks!

Yanir

[German_EE]

If you look at the datasheet you will see that they do not specify which are the input and which are the output ports, the switch is bidirectional. It will probably work in your application but at these frequencies you will need to be very careful when it comes to matching and use 50 ohm lumped lines everywhere.

Disclaimer: My RF expertise stops at about 500 MHz, I am therefore far outside my comfort zone here.

[yanir]

Thanks German_EE,
The datasheet labels them as
RF Port 1 - I'd use for Wifi
RF Port 2 - I'd use for BLE
RF Input - I'd use for the Antenna

Doesn't RF Input imply input only? I want to be wrong, and hopefully it's just poorly labeled.

[jlmoon]

How about one of these? 

http://www.minicircuits.com/pdfs/VSW2-33-10W+.pdf

or even this one if you don't need the power characteristics

http://www.minicircuits.com/pdfs/VSWA2-63DR+.pdf


They make some great stuff.
You will need to match the part to your interfaces through the associated matching networks

[krenzo]

I've worked with several RF switches, and I've never heard of one that is unidirectional.

[yanir]

I've worked with several RF switches, and I've never heard of one that is unidirectional.

It makes sense, but since I've never used one before I am proceeding with caution . I did find a vendors brochure that stated their switches are generally bidirectional implying they sell some that aren't.

How about one of these? 

http://www.minicircuits.com/pdfs/VSW2-33-10W+.pdf

or even this one if you don't need the power characteristics

http://www.minicircuits.com/pdfs/VSWA2-63DR+.pdf

They make some great stuff.
You will need to match the part to your interfaces through the associated matching networks

Thanks, I'll take a look. The first one is definitely beefy. More than I need for this.

[yanir]

Another question regarding specs.
Reflective VS Absorptive? After doing some reading I think I understand that If the switch is open it can either be a reflective or absorptive (with a 50ohm load). So when I have BLE 'off' and disconnected, if it attempted to transmit, it could either get a full reflection or be absorbed. Am I correct?

Continuing this thought, I need to check the data sheet for the part and see what kind of power it could handle being reflected back on the RF line. If it's absorptive, I don't care.
Also, since I can control in software whether or not they are transmitting during the off state I should be able to avoid any problems, but bugs happen...