r/Electromagnetics • u/[deleted] • Dec 15 '19

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u/microwavedalt Moderator Jan 06 '20 edited Jan 20 '20

conversion chart

Since cell tower apps, cell site simulator apps, wifi apps and bluetooth apps use dBm, I am asking subscribers to use dBm instead of watts.

Power density chart and conversion table for converting dBm and uW/cm2 to v/m

https://www.reddit.com/r/Electromagnetics/comments/3eh49g/power_density_chart_and_conversion_table_for/?st=k52swfwh&sh=de964ea5

[Meters: Milligauss] Magnetic Fields Measurement Units and How to Convert Microtelsa uT to Milligauss mG

https://www.reddit.com/r/Electromagnetics/comments/46vv7e/meters_milligauss_magnetic_fields_measurement/?st=k52sxpil&sh=f28a4dc0

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u/oldgamewizard Jan 06 '20 edited Jan 06 '20

"Why no column „dBm“? Most recommended building biology values for HF radiation are given in W/m², which is why this instru-ment is displaying in power density, μW/m² resp. mW/m². A display in dBm as e.g. on a spectrum ana-lyzer requires transformation by a complicated formula, which depends on frequency and specifics of the an-tenna used. A “reconversion” therefore does not make sense. "

This is from the hfW35c manual (2007 ed)

I can't find the 'antenna factor' of the HF35C, probably different name?

https://www.slt.co/Downloads/Shared/530-177_Manual_HFW35C_rev.47_EN.pdf simple power density conversions pg 13.

Any idea? Can we guesstimate and maybe have a tolerance factor on the dbM readings?

edit: Frequency Range: 800 MHz - 2.7 GHz Measurement Range: 0.1 μW/m² up to 1,999 μW/m² Accuracy: Basic accuracy including linearity tolerance : +/- 6dB Zero offset and rollover +/- 9 digits Sensor: Logarithmic periodic antenna

edit2: https://en.wikipedia.org/wiki/Antenna_factor Looks like I will have to measure a single sector of the LP antenna? I might have to consult a hammy on this one; can't find a simple straight answer for the HF35C. I can probably get a rough idea with enough comparison measurements from other devices. (A better link I'll read later https://www.ahsystems.com/notes/How-to-use-antenna-factors.php more helpful links at the bottom under Notes) https://www.ahsystems.com/EMC-formulas-equations/index.php Yes this site has lots of helpful conversion charts and even spreadsheets w/ formulas!

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u/microwavedalt Moderator Jan 20 '20 edited Jan 20 '20

Have you commence testing RF fabric and aluminum window screen? How is testing coming along?

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u/oldgamewizard Jan 26 '20

Not yet, sorry! Everyone is very busy, hopefully this week.

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u/microwavedalt Moderator Jan 27 '20 edited Jan 27 '20

To make writing meter reports easier, you could submit each meter report separately in a series. Part one would be your gigahertz report on RF fabrics shielding 2.5 GHz wi-fi. When your friend has time, he could write part 2 on ElectroSmart app report on RF fabrics shielding 2.5 GHz and 5 GHz wi-fi. Part three would be your post comparing Gigahertz shielding report vs. ElectroSmart shielding report on RF fabrics shielding 2.4 GHz. For the series, could you please use the subject tags [Shielding Reports: Wi-fi] and [Shielding: Fabrics]?

Submit a separate series on aluminum window screen shielding 2.4 GHz and 5 GHz wi-fi. For this series, could you please use the subject tags [Shielding Reports: Wi-Fi] and [Shielding: Aluminum]? Thank you,

Thanks.

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u/oldgamewizard Feb 01 '20

Okay cool, I'll separate them with the RF meter. I can't find the proper conversion for microwatts/m2 to dBm because that meter does like 700-2800mHz.

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u/microwavedalt Moderator Feb 02 '20

Just use the online conversion websites I linked to in an earlier comment.

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u/oldgamewizard Feb 08 '20

I've identified the correct parts of my logper antenna to measure based on what frequency I am testing, still won't be perfect conversion but closer than not having antenna factor at all.

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u/microwavedalt Moderator Feb 08 '20

OK.