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I'm currently using the RFD900 SMD version for an avionics bay for long range GPS capabilities. I have read the datasheet and saw this:

The RDF900ux(-SMT)/868ux(-SMT) modem has two antenna ports and firmware which supports diversity operation of antennas. During the receive sequence the modem will check both antennas and select the antenna with the best receive signal. The antenna selected during receive is then also used for subsequent transmission.

This implies that the antenna pin is able to act as a transceiver without the use of a balun. I'm just wondering from an electronics standpoint how this is possible, as I want to optimize the operation of the RFD900/smt as possible without using the shield due to size constraints (through the use of appropriate filtering, and LNA and a PA all through this singular ANT1/2)?

Datasheet for more information.

JYelton
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Lucas Webb
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  • Who says that there isn't a balun or some similar circuit or a different RX to TX frequency? – Andy aka Aug 11 '23 at 08:53
  • A value is typically used where a single-sided signal from an IC or other circuit needs to interface with an antenna that requires a differential signal, it has little to do with whether the device is transmitting or receiving. The RFF900 switches internally between tx and rx, and won’t do both at the same time. As the datasheet says, the diversity antenna doesn’t change this, the device will elect to use one antenna or the other, depending on which is giving the better reception. – Frog Aug 11 '23 at 09:13

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