Quarix During the experiment, I tested all the small items I had. The testing platform was AV3656A, with a test frequency range of 10 MHz to 3 GHz. After performing SOLT calibration, I conducted the measurements. First, the original antenna for the QuanSheng UVK6: 140 MHz and 458 MHz are the frequencies with the lowest reflection, while there are also valleys at 2.0 GHz and 2.7 GHz. Next are the original small antennas for the ADALM PlutoSDR: A 433MHz antenna for a few yuan on Taobao: A 433 MHz dual SAW BPF claiming a bandwidth of 2.5 MHz on Taobao: As the actual bandwidth increases to 10 MHz, the insertion loss also becomes significant. Finally, I found a SMA to copper coaxial cable on Taobao for only a few yuan, and surprisingly, it worked quite well. The power loss at 3 GHz is approximately 0.989 dB.
BI1NIZ Based on my observations, the first antenna seems completely unusable. It doesn't have any proper resonance points, and I suspect the testing method is incorrect. This should be done using a test fixture to simulate handheld operation.
Quarix BG5VQE Thank you for the reminder. I was also curious about why the S-parameters of the mobile antenna changed significantly during testing. If possible, I would like to test it again with a similar enclosure to see if that makes a difference.
debain Thank you for sharing the test results; I learned a lot from it. Thank you for your hard work.
BG7MHZ The testing was hard work, but unfortunately, the method was incorrect. I've borrowed a picture from a HAM friend on the "借本坛" forum.
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