Automatic antenna switching circuit using RF switch

Thread Starter

nadirEatsKoukies

Joined Dec 11, 2020
2
Hi all,
I am very new to the field of RF so excuse me if my post is not the most detailed.

I am tasked with creating a circuit which automatically switches between two antennas. In this case Antenna 1 has precedence, if it is plugged in it should be the priority, Antenna 2 is a back up and should only be switched to when Antenna 2 is not connected. Ideally the circuit should be fully analog.
I was provided with this switch https://www.mouser.co.uk/ProductDetail/Qorvo/QPC7512TR13?qs=GedFDFLaBXGSmuRUCJmdeQ==
But I can ask for another one if it is not the most suitable.

Honestly, I have no idea where to start so any help is appreciated.
Thanks
 

Papabravo

Joined Feb 24, 2006
14,831
Hi all,
I am very new to the field of RF so excuse me if my post is not the most detailed.

I am tasked with creating a circuit which automatically switches between two antennas. In this case Antenna 1 has precedence, if it is plugged in it should be the priority, Antenna 2 is a back up and should only be switched to when Antenna 2 is not connected. Ideally the circuit should be fully analog.
I was provided with this switch https://www.mouser.co.uk/ProductDetail/Qorvo/QPC7512TR13?qs=GedFDFLaBXGSmuRUCJmdeQ==
But I can ask for another one if it is not the most suitable.

Honestly, I have no idea where to start so any help is appreciated.
Thanks
I have to wonder why you were given this task when you "have no idea where to start". If I were you I would ask for a more precise statement of the requirements. The reason for this is that it is the only way you can be confident that you know what done means. If you just need one of something that works that is one possible answer. If you're going to make 100,000 of them you'll need to gather a bit more information. Some performance specifications would be helpful, for example how much attenuation of the signal is allowed?

Next you have to make a decision on what control power supply voltage you intend to use between 2.7 and 5.5 volts, followed by what kink of control logic family might be appropriate. I highly recommend getting a couple of the eval boards for the part.

Next how are you going to make the switching decision?
What information is available to inform that decision?
How are you going to power this device?

That should keep you off the streets for a while.
 
Last edited:

vu2nan

Joined Sep 11, 2014
166
Here's a scheme, based on sensing high SWR.

1.JPG

To start with, the default antenna is '1'.

When it goes bad, the 'SWR High' pulse sets the magnetic latch relay K1, which energises the coaxial relay K2, to make '2' the default antenna.

K1 is to be reset, after rectifying '1', to make it the default antenna once again.

The SWR sensing circuit is to be worked out. Freewheeling diodes are not shown.

Nandu.
 
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