RF exposure from CB radio use

[FPR1981]

We all know that RF is hazardous, in varying degrees based on frequency, output power and distance away from antenna. Is the guy who has a dipole indoors exposing himself to dangerous levels of RF?

What about the channel 6 guys who are running kilowatts of power? Are they cooking their neighbor's insides with RF?

Interested to read the spread of responses.

 

[KB4MSZ]

When thinking logically about the phenomenon surrounding channel 6, this hypothesis could explain a great many things.

 

[nd5y]

We all know that RF is hazardous, in varying degrees based on frequency, output power and distance away from antenna. Is the guy who has a dipole indoors exposing himself to dangerous levels of RF?

Probably not.

What about the channel 6 guys who are running kilowatts of power? Are they cooking their neighbor's insides with RF?

If that was possible there would be lots of reports of people dying from CB exposure.

A long time ago I worked at a goverment installation that had a two mile long antenna array of inverted V dipole antennas over an aluminum grid ground plane. Over 2000 antennas spaced 4 ft. apart (1 wavelength at 216.98 MHz). Each dipole had a 200 W amplifier under it.
It didn't affect the people who worked around it.
It didn't kill the sparrows that build nests between the antennas and ground plane.
It didn't kill the bugs and spiders that lived on it.

Before that I had a job inspecting and calibrating medical equipment. Electrosurgery units put out up to about 100 W or so at frequencies of about 500 kHz to 1 MHz if I remember right. That small amount of power at the tip of a hand held probe will cut and cauterize (burn) skin and internal tissue, but you can climb live AM broadcast station towers that operate at the same frequencies with thousands of watts and not get burned.

 

[FPR1981]

Probably not.

If that was possible there would be lots of reports of people dying from CB exposure.

A long time ago I worked at a goverment installation that had a two mile long antenna array of inverted V dipole antennas over an aluminum grid ground plane. Over 2000 antennas spaced 4 ft. apart (1 wavelength at 216.98 MHz). Each dipole had a 200 W amplifier under it.
It didn't affect the people who worked around it.
It didn't kill the sparrows that build nests between the antennas and ground plane.
It didn't kill the bugs and spiders that lived on it.

This is good information, and exactly what I was looking for.

 

[2e0mfp]

I've had an RF burn from a CB, when I was holding the antenna to go portable (years ago), but you're not meant to be that close, lol.

Regarding RF exposure, our local regulatory body here in the UK, OFCOM, has sent an email to all amateurs regarding compliance with "International Commission on Non-Ionizing Radiation Protection (ICNIRP) Guidelines for the protection of the general public from electromagnetic fields (EMF)" and we're supposed to work out the exposure to protect the general public, including putting up warning signs if the public comes within the 'danger zone'. They even supply a spreadsheet for download to work out the exposure levels.
here's the requirements: Guidance on EMF compliance and enforcement
and here's the calculator: EMF calculator
if you want to have a look.
Coming to a country near you soon, maybe, 'public safety' and all that.

 

[WB9YBM]

Is the guy who has a dipole indoors exposing himself to dangerous levels of RF?

What about the channel 6 guys who are running kilowatts of power? Are they cooking their neighbor's insides with RF?

question #1 depends on 1) power level & 2) distance from the antenna.

on question #2, I once heard someone working at--I think it was CBS--spent a lot of time behind a UHF dish antenna & ended up dying from cancer; the article I read linked the two.

Since, a few years ago, the FCC implemented a rule that the amateur radio community had to be aware of (and limit) RF exposure they came up with a formula and/or table showing maximum suggested exposure limits based on frequency & distance from the antenna. Either the FCC or the American Radio Relay League (ARRL) should have details. Here are a few I found:
RF exposure limits (fcc.gov)
Radiofrequency and Microwave Radiation - Standards | Occupational Safety and Health Administration (osha.gov)
47 CFR § 1.1310 - Radiofrequency radiation exposure limits. | CFR | US Law | LII / Legal Information Institute (cornell.edu)
RF Exposure (arrl.org)
Radio Frequency Safety | Federal Communications Commission (fcc.gov)
RF Exposure - Evaluating Your Station | Ham Radio School.com
How Much RF-EMR Exposure is Safe? – Scientists for Wired Technology (scientists4wiredtech.com)
Radiofrequency Exposure Limits Revised: FCC Proposes Expanding Rules to Cover Higher Frequencies | CommLawBlog

 

[FPR1981]

I read an argument online somewhere, under the theory of "frequency matters" that alleged the 11-meter frequencies generated less harmful RF than something like VHF or UHF. I wish I could find it.

 

[prcguy]

I think it would be difficult if not impossible to exceed the exposure limits with a stock CB radio. Not only do you have a time limit of exposure over 6 minutes in the formula, you also have to consider the energy spread out over the length of a human body. At 146MHz or 446MHz, 5 watts into a 7" long loaded VHF antenna or a full length 6" quarter wave as typically found on a hand held is right at the limit for occupational/controlled exposure limits at 3 to 4" from your head with 6 minutes of continuous transmitting. In both cases all the RF is concentrated in a fairly small area of your head.

Its hard to get that close to a CB antenna and if you could hug a 5ft long Firestick it may not exceed the limits. The lower portion of the antenna, maybe the lower 1/3 will have more radiation than the top. The energy will be spread out over a larger area due to the longer wavelength and size of the antenna. You would have to probe it with a RF exposure measuring meter to know for sure, but I believe a stock CB would be safe at any distance from the antenna.

 

[prcguy]

The 30 to 300MHz range have the same levels in the FCC calculation. Above 300MHz it takes less energy to exceed the spec. At 27MHz its only a few % less energy needed to reach the spec.

I read an argument online somewhere, under the theory of "frequency matters" that alleged the 11-meter frequencies generated less harmful RF than something like VHF or UHF. I wish I could find it.

 

[RFI-EMI-GUY]

I would be more concerned about staring at my food cooking in a microwave oven than occasional use of a CB radio.

 

[slowmover]

I would be more concerned about staring at my food cooking in a microwave oven than occasional use of a CB radio.

I thought everyone leaned forehead against oven door re-heating yesterday’s coffee first thing in the morning. Inter & Intra Cellular Physical & Chemical Excitation achieved after downing that first cup.

Hell, don’t you wet the sponge before using it?

.

 

[RFI-EMI-GUY]

I thought everyone leaned forehead against oven door re-heating yesterday’s coffee first thing in the morning. Inter & Intra Cellular Physical & Chemical Excitation achieved after downing that first cup.

Hell, don’t you wet the sponge before using it?

.

I am trying to respect my blood brain barrier these days.

 

[Duckford]

When thinking logically about the phenomenon surrounding channel 6, this hypothesis could explain a great many things.

View attachment 101683

Watching some of these radio types on the Youtube, listening to some of them talk, looking at their peaked out eyes. Listening to some of the babbling on high power CB channels. I swear some of those folks have cooked themselves with some serious levels of RF.

I used a calculator that figures the US regulations for RF exposure, and it basically stated that nobody should stand within 20 feet of my 2 meter omni base station setup while in operation. I'm not sure how reliable that formula is or not, but I think it is best I keep my distance with my G7.
Some of those guys with super amps, and who get on those things for hours at a time talking to themselves while watching their wattmeters, I can truly believe might have some heat damage self inflicted through their bold activities.