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Half duplex RF tranceiver by using LINX RF modules

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darvaish

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I have got RF modules ,TXM-418-LR(transmitter) and RXM-418-LR(receiver) and the antenna ANT-418-PW-RA.

Now i want to make a half duplex tranceiver by using these RF modules.For that i can understand that i will need a SPDT RF switch to connect a single antenna to the transmitter and receiver module.
But for some reasons i cant go for above solution.Now if i will place the transmitter and receiver modules side by side then i can manage to get a very small distance (around 8mm) between the antenna feed pins of both modules.Now if i connect both antenna feed pins through a tab very near to the modules on the PCB and connect a single antenna to that tab and then control my transmitter and receiver through a microcontroller using the power down pins of modules such that only one of them remain active at a time
Will this thing work properly as a Half duplex tranceiver?

Dtasheets can be consulted for reference at following links:

https://www.linxtechnologies.com/images/products_cat/rf_modules/lr_series/lr-rxm_manual.pdf

https://www.linxtechnologies.com/images/products_cat/rf_modules/lr_series/lr_txm_manual.pdf

https://www.linxtechnologies.com/in...tennas&subcategory=monopole&series=ra_series


Thanking in anticipation
 
darvaish said:
I have got RF modules ,TXM-418-LR(transmitter) and RXM-418-LR(receiver) and the antenna ANT-418-PW-RA.

Now i want to make a half duplex tranceiver by using these RF modules.For that i can understand that i will need a SPDT RF switch to connect a single antenna to the transmitter and receiver module.
But for some reasons i cant go for above solution.Now if i will place the transmitter and receiver modules side by side then i can manage to get a very small distance (around 8mm) between the antenna feed pins of both modules.Now if i connect both antenna feed pins through a tab very near to the modules on the PCB and connect a single antenna to that tab and then control my transmitter and receiver through a microcontroller using the power down pins of modules such that only one of them remain active at a time
Will this thing work properly as a Half duplex tranceiver?

As I understand it, you are wanting to simply join both aerial connections from the modules together?, and then connect a single aerial to that point?.

This is going to cause a severe mismatch!.

I suggest you look for 'pin diode' switches, which will switch between the two without using a relay.
 
Yes you are right that i simply want to join both aerial connections from the modules together, and then connect a single aerial to that point.

Can you please explain how this will cause a mismatch even when only one of the modules i.e either transmitter or receiver will be ON at a time
I will switch off the transmitter while receiving and also receiver will be switched off while transmitting

Thanks
 
darvaish said:
Can you please explain how this will cause a mismatch even when only one of the modules i.e either transmitter or receiver will be ON at a time
I will switch off the transmitter while receiving and also receiver will be switched off while transmitting

Because they are still connected! - removing the power doesn't disconnect them.

Assuming they are 50 ohms impedance, adding the receiver in parallel with the aerial places a 25 ohm load on the transmitter.
 
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