Register Account

Login Help

Forum Home - Rules - Help - Login - Forgot Password
Members can access, post and reply to the forums below. Before you do, please first read the RULES.

Usable RF power density meter for safety?

Aug 4th 2018, 18:00


Joined: Jul 11th 2018, 12:26
Total Topics: 0
Total Posts: 0
Hi All,

First time posting. I have a 2-meter FM rig with an indoor antenna placed on a windowsill about 7-8 feet from the radio in a bedroom-sized room in my house. The antenna is a 5/8-wave telescoping vertical made for an HT. I commonly transmit with 25 watts, which is required to reliably hit the repeaters about 35 miles from here. (10 watts gets in only with fading and intelligibility issues.)

According to calculations, this arrangement should be safe for a controlled environment even under "worst-case" assumptions. But I question this. The distance is probably nearfield. Sometimes I'm between the antenna and the radio, and it's possible the radio acts as part of the antenna system (though I do have an isolator on the line). And this is a pretty small room containing lots of conductive objects--metal desk, metal workbench, etc.

So the RF power density in the room is--who knows?

I'm considering switching to a moxon antenna, which should direct most of its energy out the window, and which is more of a balanced antenna type. Still, I was thinking that in this kind of scenario, the only way to really be sure it's safe would be to take measurements.

Online there are a lot cheap RF meters for sale, which surely won't work. Most only have meaningful results in bands like 900 MHz and 2.4 GHz, despite their advertised bandwidths. One independent evaluation done by an EMC lab in Germany that I read rated every meter they tested as useless for almost everything--certainly for my purposes.

So I was wondering whether anyone here has had experience using a calibrated professional meter, and might point me in a helpful direction as far as where I might look for such a thing. Also, any other suggestions that might be helpful for my particular situation would be welcome.

Nov 6th 2021, 01:45


Joined: Dec 24th 2013, 05:58
Total Topics: 0
Total Posts: 0
Did you find an RF power density meter? I am asking because I have a nice Holaday HI-3012 from the 1990s. I think the FCC used them. However, I am not sure it is still calibrated and am looking for a way to check the calibration.
Richard AE6XO
Please reply to:
Nov 8th 2021, 07:38


Super Moderator

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
Narda Safety Test solutions has been a industry leader for decades.

Zak Lau W1VT
ARRL Senior Lab Engineer

Back to Top


Instragram     Facebook     Twitter     YouTube     LinkedIn