When measuring radiation inside the shield box....

RE: When measuring radiation inside the shield box....

Andreas — Mon, 31 Aug 2020 09:55:06 GMT

Hi,

[quote user="moon.kim"]Any way, I guess it's important to keep the antenna and device position constant at all times.[/quote]

Exactly. This is an inaccurate way of measuring output power, but if you are able to compare with a golden device it should work ok. This requires that the devices are placed identically each time.

Best regards,

Andreas

RE: When measuring radiation inside the shield box....

moon.kim — Mon, 31 Aug 2020 09:16:13 GMT

HI.

Thank you.

I wanted to know how to place the antenna in the shield box so that it is less affected by reflected waves.

Because, Output power was measured low on certain frequency channels depending on device location.

This is because you have to measure a lot of devices and get a uniform result for comparison.

Any way, I guess it's important to keep the antenna and device position constant at all times.

RE: When measuring radiation inside the shield box....

awneil — Mon, 31 Aug 2020 09:04:13 GMT

[quote userid="83275" url="~/f/nordic-q-a/65336/when-measuring-radiation-inside-the-shield-box/267129"]I can't understand Awneil and your advice[/quote]

Sounds like you really need to get someone who knows how to do RF measurements to help you with this.

RF work is a specialist area!

RE: When measuring radiation inside the shield box....

Andreas — Mon, 31 Aug 2020 08:48:09 GMT

Hi,

It's hard to recommend anything without knowing what your goal is, what are you trying to do?

The walls will reflect the radio signals, exact how they reflect and how the signals have to propagate to get to the spectrum analyzer antenna depends on the position of the device and the antenna. Typically I would place the device and antenna not this close to the walls, but as long as you place them similarly for each measurement you should get consistent results.

Best regards,

Andreas

RE: When measuring radiation inside the shield box....

moon.kim — Mon, 31 Aug 2020 07:21:00 GMT

Hi, Andreas

Sorry. I can't understand Awneil and your advice.

First, The shield box I use is not anechoic.

Does this mean that it is okay if there is a distance of 12.5cm or more from the shield box wall?

[quote userid="6462" url="~/f/nordic-q-a/65336/when-measuring-radiation-inside-the-shield-box/266954"]Remember: at 2.4GHz, the wavelength is only 12.5cm ...[/quote]

And you say....

[quote userid="9102" url="~/f/nordic-q-a/65336/when-measuring-radiation-inside-the-shield-box/266976"]The position of the device and the antenna will change how much is reflected and transmitter within the box and possibly detune the antennas if placed close to the walls.[/quote]

You mean it should be placed like this?

RE: When measuring radiation inside the shield box....

Andreas — Fri, 28 Aug 2020 11:22:51 GMT

Hi,

As Awneil kindly mentions, a shielded box is not necessarily anechoic, especially in the 'box size'. The position of the device and the antenna will change how much is reflected and transmitter within the box and possibly detune the antennas if placed close to the walls.

Best regards,

Andreas

RE: When measuring radiation inside the shield box....

awneil — Fri, 28 Aug 2020 10:21:40 GMT

What, exactly, are you using as the "shielded box" ?

In particular, is it anechoic at the test frequency?

Remember: at 2.4GHz, the wavelength is only 12.5cm ...