How can I measure LTEM TX power after the antenna impedance matching circuit

RE: How can I measure LTEM TX power after the antenna impedance matching circuit

mathiaso — Tue, 18 Mar 2025 09:11:57 GMT

Great to know!

Have a nice day, you too!

RE: How can I measure LTEM TX power after the antenna impedance matching circuit

Carla31zv — Tue, 18 Mar 2025 08:08:30 GMT

Hello,

I've found the answer on this post NRF9160 LTE RX/TX Functionality test - XREFTEST so I close this ticket.

Have a nice day!

RE: How can I measure LTEM TX power after the antenna impedance matching circuit

mathiaso — Mon, 17 Mar 2025 14:12:06 GMT

param1 in both the TX and RX tests should let you decide which frequency to test. However, I'm not sure what you want to TX while measuring?

RE: How can I measure LTEM TX power after the antenna impedance matching circuit

Carla31zv — Thu, 13 Mar 2025 16:25:04 GMT

Precision in measurement is not a top priority for me. I was trying to use the AT command %XRFTEST RX to enable the RF receiver and measure the signal power sent by another devkit. However, I believe this isn't feasible because one devkit transmits on uplink frequencies, while the other receives on downlink frequencies

RE: How can I measure LTEM TX power after the antenna impedance matching circuit

mathiaso — Thu, 13 Mar 2025 16:20:59 GMT

[quote user="Carla31zv"]I would like to know—as mentioned in this ticket—whether it's possible to measure the transmitted signal power from one nRF9160 DK using another nRF9160 DK.[/quote]

Ok, understood. For this purpose, you should use a spectrum analyser, rather than a DK. The DK would likely not give very precise measurements, but I don't know what you're planning to use them for?

If using the TX test %XRFTEST at any time, beware of the caution about restricted bands.

RE: How can I measure LTEM TX power after the antenna impedance matching circuit

Carla31zv — Thu, 13 Mar 2025 09:13:23 GMT

Thanks for the explanation.

I would like to know—as mentioned in this ticket—whether it's possible to measure the transmitted signal power from one nRF9160 DK using another nRF9160 DK.

Also, can these operations be performed using the AT command %RFTEST?

RE: How can I measure LTEM TX power after the antenna impedance matching circuit

mathiaso — Wed, 12 Mar 2025 15:34:55 GMT

Thank you, Carla.

What was the reasoning behind adding that matching network, with those specific values?

As can be read in the PS, the ANT pin is already matched to 50 ohms. Your connector, differently from what would be the case if it were an antenna, likely has an impedance of 50 ohms as well. This is also the reason why the nRF9160 DK has a matching network for the antenna but not for the connector.

RE: How can I measure LTEM TX power after the antenna impedance matching circuit

Carla31zv — Wed, 12 Mar 2025 13:45:15 GMT

Hello, yes it is after antenna's matching network of my custom board, pin ANT_4G. Here you can see my setup:

RE: How can I measure LTEM TX power after the antenna impedance matching circuit

mathiaso — Wed, 12 Mar 2025 13:39:12 GMT

Hi, Carla.

I'm not quite sure I'm following why you would want to measure the output power after the antenna's matching network. Do you mean between the ANT pin and the antenna-matching network, where the connector is placed on the nRF9160 DK? Would you be able to illustrate and/or describe your setup and what you want to achieve more in detail?

Best regards,
Mathias