I'm 2 months into my RF and SDR learning, and I'm stuck in the middle of a project, looking for some clues:
First, as detailed here, I connected two 125kHz RFID antennas through a 5m, 2-wire copper cable (no coax), and I was able to relay the RFID signal through that link (my tag was recognized by the reader).
As a second step, I want to replace the copper cable link with a radio link:
[RFID transmitter antenna] - [RFID receiver antenna 1] - [HamItUp 1] - [HF antenna 1] - [HF antenna 2] - [HamItUp 2] - [RFID receiver antenna 2] - [RFID tag]
so I connected the input port of a HamItUp nano to one of the RFID antennas, and the output port to a 60cm antenna (300000000/125125000/4); using a remote HackRF with its own antenna, I was able to receive the signal from the RFID emitter -> HamItUp -> antenna over the air at 125.125MHz.
I then connected the input port of a second HamItUp nano to the second RFID antenna, and its input port to a second 60cm antenna, identical to the first; this way I was expecting the radio link to work, and being able to read my RFID tag at the second; however, despite having verified with HackRF that the signal is reaching the second RFID antenna, this time the tag is not recognized.
I already tried switching the input and output ports of the first and second HamItUp, with no luck; I feel I'm missing something, and would appreciate some guidance.