Charlie Tango 11m DX Radio Group Forum
Would you like to react to this message? Create an account in a few clicks or log in to continue.


Welcome to the Charlie Tango DX Group. The home of ALL things Radio - CB, 11m DX, Amateur, PMR446, PLD, Network and Data. We welcome all radio enthusiasts of all knowledge levels. Join today and claim your own unique World Famous CT Call-sign
 
HomeEventsCalendarFAQSearchRegisterLog in
New eQSL Email Service: Exchange eQSL cards quickly and easily with your very own eQSL email address like this... 26CT000@eQSL.me or 26CT000@charlietango.co.uk - See Latest News forum for more details.
Latest Buxton 2020 News: Unfortunately, due to the Covid-19 pandemic we have had to cancel this year's Buxton date. Sorry for any inconvenience.
Navigation
Useful Radio Sites
Log in
Username:
Password:
Log in automatically: 
:: I forgot my password
CT Bill Board





Views This Year
All Time Views
Classified Adverts

Latest topics
» Colt excalibur
Indoor CB-antenna - safe? Icon_minitimeYesterday at 10:11 pm by Colt

» RF Dummy Load - DIY
Indoor CB-antenna - safe? Icon_minitimeYesterday at 9:05 pm by Swadeyboy

» SS9900 and Power mic's
Indoor CB-antenna - safe? Icon_minitimeYesterday at 6:47 pm by blacklizard71

» 2 ele quad /P
Indoor CB-antenna - safe? Icon_minitimeYesterday at 3:15 pm by Alan Pilot

» Getting disillusioned
Indoor CB-antenna - safe? Icon_minitimeYesterday at 2:14 pm by Ethergoddle

» CRT 3900 - 27.305 on channel 16
Indoor CB-antenna - safe? Icon_minitimeYesterday at 12:48 pm by Alan - Mirror Man

» Call sign request
Indoor CB-antenna - safe? Icon_minitimeYesterday at 11:11 am by JB16170

» New member introduction. (Issued)
Indoor CB-antenna - safe? Icon_minitimeSat Sep 26, 2020 8:35 pm by John123

» PMR446 NET
Indoor CB-antenna - safe? Icon_minitimeSat Sep 26, 2020 6:53 pm by Addaz93

Keywords
Calling chart list radio tickets ss9900 midland Mobile alan president frequency bazooka power call division callsign Baofeng Mckinley yaesu ALINCO 9900 lincoln sign antenna Sirio tango
QRZ Database

 

 Indoor CB-antenna - safe?

Go down 
AuthorMessage
Wittfogel
New Member
New Member
Wittfogel

Call Sign : 21-CT-026
Posts : 5
Times Thanked : 0
Join date : 2020-03-28
QTH or Location : Stockholm, Sweden
Equipment Used : President McKinley

Indoor CB-antenna - safe? Empty
PostSubject: Indoor CB-antenna - safe?   Indoor CB-antenna - safe? Icon_minitimeWed Apr 01, 2020 7:06 pm

Hi friends,

I just installed my first TX-antenna in the window of my room (in an apartment). Far from optimal, I know, but it’s what’s possible at the moment.

It’s a magnet mount ”Sirio Hi Power 3000 N” which I put on a 1m long metal thing for now.

Anyway, I did some reading on RF-radiation and started to wonder how safe it would be to use at 12 watt SSB? My chair/table is about ~2m from the antenna.

Will I get fried? Some weird health issue? Will all the other tech in the room complain?

Thanks in advance,
Samuel
Back to top Go down
View user profile
Northern Crusader
Major contributor
Major contributor


Call Sign : M0GVZ / 26CT1760
Posts : 285
Times Thanked : 20
Join date : 2019-11-13
QTH or Location : IO94SA
Equipment Used : Icom 7300, TS480, President McKinley, Albrecht AE6110, CRT Mike
Age : 50

Indoor CB-antenna - safe? Empty
PostSubject: Re: Indoor CB-antenna - safe?   Indoor CB-antenna - safe? Icon_minitimeWed Apr 01, 2020 7:38 pm

Here's a handy RF Density Power calculator to let you know if you're within FCC safe limits. Whilst we're not covered by the FCC it's OK to use for an indicator.

http://hintlink.com/power_density.htm

Putting in your figures and assuming 0dB gain and 6ft from the antenna the power density is 0.0286 mW/cm2, well under the "uncontrolled environment" (where you have no control over people going near it) maximum permissable exposure limit of 0.2519 mW/cm2

Power density drops extremely rapidly even just a couple of feet from an antenna, it's why all those claims about people being fried by mobile phone masts, especially 5G, are laughable at best.

It is possible the other tech in the room will complain but that might be from "common mode RFI" from the lack of a suitable ground plane rather than RF from the antenna.
Back to top Go down
View user profile
Wittfogel
New Member
New Member
Wittfogel

Call Sign : 21-CT-026
Posts : 5
Times Thanked : 0
Join date : 2020-03-28
QTH or Location : Stockholm, Sweden
Equipment Used : President McKinley

Indoor CB-antenna - safe? Empty
PostSubject: Re: Indoor CB-antenna - safe?   Indoor CB-antenna - safe? Icon_minitimeWed Apr 01, 2020 7:55 pm

Thanks for the info, and a good tip!

I googled the gain, and here they say that the antenna has a 5 dBi gain: http://www.4x4cb.com/public/item.cfm?itemID=693

Which brings the power density up to 0.2312 mW/cm2... Still OK, but I mustn’t sit closer! Smile

Even if it was to exceed by a little, what would the effect be? Warm cheeks?
Back to top Go down
View user profile
Northern Crusader
Major contributor
Major contributor


Call Sign : M0GVZ / 26CT1760
Posts : 285
Times Thanked : 20
Join date : 2019-11-13
QTH or Location : IO94SA
Equipment Used : Icom 7300, TS480, President McKinley, Albrecht AE6110, CRT Mike
Age : 50

Indoor CB-antenna - safe? Empty
PostSubject: Re: Indoor CB-antenna - safe?   Indoor CB-antenna - safe? Icon_minitimeThu Apr 02, 2020 12:59 pm

Wittfogel wrote:
Thanks for the info, and a good tip!

I googled the gain, and here they say that the antenna has a 5 dBi gain: http://www.4x4cb.com/public/item.cfm?itemID=693

No it doesn't, it really doesn't at all. That's a marketing bollocks claim that is as valid as the one that claims an Antron A99 has 9.9dBi of gain, or in other words can radiate a signal 10 times stronger than the one fed into it which even a full size 3 element beam can't manage to do.

Even full size verticals like the 24ft 5/8 wave antennas with a perfect RF ground only have gain of 3 to 4 dBi and even then that is only at one angle of take of from horizontal. You've a short antenna with a poor RF ground so 0dBi is probably being very generous.
Back to top Go down
View user profile
Wittfogel
New Member
New Member
Wittfogel

Call Sign : 21-CT-026
Posts : 5
Times Thanked : 0
Join date : 2020-03-28
QTH or Location : Stockholm, Sweden
Equipment Used : President McKinley

Indoor CB-antenna - safe? Empty
PostSubject: Re: Indoor CB-antenna - safe?   Indoor CB-antenna - safe? Icon_minitimeThu Apr 02, 2020 1:04 pm

Well, I bow to your superior wisdom - and am all the happier for it! No need to dwell further on the matter!

Thanks again for the help,
Samuel
Back to top Go down
View user profile
Northern Crusader
Major contributor
Major contributor


Call Sign : M0GVZ / 26CT1760
Posts : 285
Times Thanked : 20
Join date : 2019-11-13
QTH or Location : IO94SA
Equipment Used : Icom 7300, TS480, President McKinley, Albrecht AE6110, CRT Mike
Age : 50

Indoor CB-antenna - safe? Empty
PostSubject: Re: Indoor CB-antenna - safe?   Indoor CB-antenna - safe? Icon_minitimeThu Apr 02, 2020 1:11 pm

You don't want to be touching it but you'll be safe at the power level you're using at the distance you are.

You asked what the risks are. Ultimately RF burns if it's serious enough. You don't feel you're getting burned though, it just feels like a tingling but you can get third degree burns. You don't want to be holding the whip when you transmit.

In regards to the gain, these are charts of gain from Steve G3TXQ who was a noted antenna designer of high repute who re-designed the Hexbeam two element beam to a more efficient wider bandwidth version. What he didn't know about antennas was not worth knowing. He released his designs for free and never manufactured them commercially so had no monetary benefit to drive him to make claims about the antenna. The gain of the re-designed one was only 5-6dBi and this was a full sized antenna, not one half of the size of a quarter wave so only about 25% of the efficiency of a quarter wave .

Indoor CB-antenna - safe? 12m_perf
Back to top Go down
View user profile
Sponsored content




Indoor CB-antenna - safe? Empty
PostSubject: Re: Indoor CB-antenna - safe?   Indoor CB-antenna - safe? Icon_minitime

Back to top Go down
 
Indoor CB-antenna - safe?
Back to top 
Page 1 of 1

Permissions in this forum:You cannot reply to topics in this forum
Charlie Tango 11m DX Radio Group Forum :: Help and Discussion Forums :: Antenna Discussion-
Jump to: