Is it possible to estimate the gain of an antenna in this way?

haha丶

Is it possible to estimate the gain of an antenna in this way? [Copy link]

As shown in the figure, this is about using a signal generator and a spectrum analyzer to estimate the gain of an antenna by its transmit and receive power without a microwave darkroom.

When I want to measure the antenna in the picture above, after drilling holes at the marked points to connect them to the ground, won’t that short-circuit the microwave source, and won’t that burn the microwave source?

Can I test this way?

w494143467

I remember that when we tested the antenna gain, we directly connected the spectrum analyzer to the antenna output without transmitting the signal through the air. If we were worried that the gain was too high to be detected, we could add an attenuator.

w494143467

The method you show seems to be used for signal detection.

haha丶

w494143467 Published on 2021-7-9 13:36 I remember that when we tested the antenna gain, we directly connected the spectrum analyzer to the antenna output without transmitting the signal through the air. If we were afraid that the gain would be too large and we couldn't detect it, we could...

Thank you for your reply. Where do you usually connect the antenna output? I don't quite understand it.

chunyang

w494143467 Published on 2021-7-9 13:36 I remember that when we tested the antenna gain, we directly connected the spectrum analyzer to the antenna output without transmitting the signal through the air. If we were afraid that the gain would be too large and we couldn't detect it, we could...

What you get by doing this is output power, which has nothing to do with the antenna.

chunyang

The estimation method mentioned in the original post is probably difficult to implement. The method I have used is the comparison method.

First, use an antenna with known gain as a benchmark. This method requires two versions of the same front-end circuit, one with SMA or other connector output for connecting to a standard antenna, and one with a PCB antenna. Under the same test environment, adjust the output power of the front-end circuit so that the curves of the standard antenna board and the PCB antenna board on the spectrum analyzer overlap, and then the approximate gain of the PCB antenna can be obtained based on the power difference. It is even simpler if the spectrum supports direct reading, and there is no need to change the output power of the standard antenna board. This method can only be roughly estimated, but the operation is relatively simple, especially when both use external antennas. I use this comparison method for antenna evaluation, and the results are clear at a glance, very close to the measurement results of professional instruments, but the values are slightly rough (the resolution can only reach one decimal place), but it is usually sufficient.

btty038

The gain of this antenna can be measured by the comparison test mentioned by the teacher on the 6th floor. You can compare the antenna to be tested with the standard antenna to know the gain and various indicators of the antenna to be tested.

btty038

You can test the radiation signal in space. No matter how high the antenna gain is, the signal you receive will be weak. Even if it is high-power radiation, the antenna is generally not that big.

w494143467

chunyang posted on 2021-7-9 20:49 What you get by doing this is the output power, which has nothing to do with the antenna.

Yeah, that’s a bit off topic.

btty038

haha丶

Thanks for the help, I have read all the suggestions you gave me before, but now I find that there is no reply. Thanks again for your help, thank you very much!!!