> At 10:45 AM 4/25/2006, Peter Sundberg wrote:
>>You can download a program that does all calculations for you, be it
>>yagis,
>>dipoles, verticals or what..
>
> Very slick... and makes it easy to check across bands
>
> Does it take into account nearfield effects for low gain antennas?
>
> e.g. for a dipole or inverted V close to the ground, it's the ends that
> present the RF safety problem, not the far field radiation
Generally if you are talking inverted V you are taling 150, 75, or 40. Evne
when running the full legal limit, key down on those bands you can get
within a couple of feet of the ends of the antennas. If they are high
enough off the ground that no one can reach up and touch it they will
probably pass the test.
>
> Another problem I ran into was with a phased array, where there's a lot of
> circulating power among the elements. I suspect that for any
Even then, don't you have to get pretty close to any particular element even
in the hear field as inside a phased array?
Roger Halstead (K8RI and ARRL 40 year Life Member)
N833R - World's oldest Debonair CD-2
www.rogerhalstead.com
> superdirective antenna (e.g. a Yagi) this might also be the case, since
> there's energy stored in the near field.
>
>
>
>
>
>>Have a look at http://www.sm2cew.com/download.htm
>>
>>You will find the VK3UM Site and Radiation Calculator version 5.1
>>(EMRCalc.exe) if you scroll down the page a bit.
>>The program does not need an install, just run the EXE-file.
>>
>>When it comes up it is in VHF/UHF/SHF mode, click a small box marked "HF"
>>in the "Frequency" box to get the HF options and antennas.
>>
>>Different radiation limits (standards for different countries) can be
>>chosen.
>>
>>73/Peter SM2CEW
>>www.sm2cew.com
>>
>>
>>
>>
>>
>>
>>At 23:56 2006-04-24 , Bill Tippett wrote:
>> >N6KJ wrote:
>> >
>> >>Actually, what I'm trying to do is figure out the radiation pattern on
>> >>the ground. Why? I'm doing RF Exposure calculations and rather than
>> >>assume the worst case exposure on the ground based upon the gain of
>> >>the antenna, I'd like to know what the actual gain is below the
>> >>antenna on the ground. I'm assuming it will be considerably less.
>> >>For example, what is the gain of my antenna at a 45 degree angle in
>> >>front of my yagi, but on the ground?
>> >
>> > OK I understand now. Here is what I
>> >would use if I were you:
>> >
>> >http://n5xu.ae.utexas.edu/rfsafety/
>> >
>> > 73, Bill W4ZV
>> >
>> >
>> >
>> >
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