How to monitor 5G field strength - Page 1
Forum section: electronics / rf-microwave

author: IconicPCB
author_rank: Super Contributor
timestamp: September 16, 2019, 02:00:50 am
content: Is there a relatively painless and inexpensive solution to monitoring 5G field strength both in-band and out of band or more to the point from about 800MHz to 5GHz.I appreciate the nature of the wide-band signal and a requirement to measure signal level within this constraint...butcould a 5G modem be pressed into service such that the signal level pin usually found on modems of this kind if available could provide an indication of field strengthandcould this pin be calibrated to provide this information?

author: coppercone2
author_rank: Super Contributor
timestamp: September 17, 2019, 04:00:43 am
content: don't modems tell you signal power in dbm on a channel?

author: TheUnnamedNewbie
author_rank: Super Contributor
timestamp: September 17, 2019, 05:18:51 am
content: Field strength is not the same as signal power. I guess in the far field they are related though, by the free-space impedance. But field strength technically just refers to the magnitude of the E and H field, not necessarily the power propagating.

author: radiolistener
author_rank: Super Contributor
timestamp: September 17, 2019, 07:15:35 am
content: Signal level depends on antenna size, efficiency and field strength. So, you can use your modem with dBm indication for measurement. But you're needs to calibrate it with some known field strength level. When you know dBm value for known field strength on specific modem, you can use it to measure field strength

author: jujun
author_rank: Regular Contributor
timestamp: September 17, 2019, 12:39:03 pm
content: Because the 5G use dynamic beamforming you cannot.It's a big problem, because you cannot know is you are under the limits fixed by the laws.

author: radiolistener
author_rank: Super Contributor
timestamp: September 17, 2019, 01:24:06 pm
content: Quote from: jujun on September 17, 2019, 12:39:03 pmI think it will not affect field strength measurement with modem power level dBm indication.The only problem here is that field strength may be significatly changed some time after measurement.For exampel, you're measured power density 10 mW/cm^2, but a hour later it may be changed. So, you cannot be sure that it is always 10 mW/cm^2.

author: jujun
author_rank: Regular Contributor
timestamp: September 17, 2019, 05:00:51 pm
content: The changes in strength will be so quick that your measurement will not have any meaning.The beamforming occurs at a very high speed, because it must be able to track cars.And there is also all the reflections from all this beams, it's a big mess, changing quickly.

author: radiolistener
author_rank: Super Contributor
timestamp: September 17, 2019, 05:45:18 pm
content: jujun, but when it is measured by modem, it will be always at main lobe of the beam. The beam will be changed after transmission, when measurement is already performed

author: IconicPCB
author_rank: Super Contributor
timestamp: September 27, 2019, 01:19:33 am
content: Thank You all for Your opinions.I intend to use the so called simple Spectrum analyser available on ebay/alibaba/taobao...While the gear is a bit deaf it still boasts a 50dB dynamic range which should be sufficient for my purposes.