Re: 150Khz Antenna question

"christofire" <christofire@[EMAIL PROTECTED]
> wrote in message 
news:5sydnRVLb6_dU_bVnZ2dnUVZ8vSdnZ2d@[EMAIL PROTECTED]
>
> "Joerg" <notthisjoergsch@[EMAIL PROTECTED]
> wrote in message 
> news:r7Pak.8821$89.4911@[EMAIL PROTECTED]
>> Tom Bruhns wrote:
>>> On Jul 2, 7:29 am, "Jacques St-Pierre" <multe...@[EMAIL PROTECTED]
>
>>> wrote:
>>>> Anyone can help me with the design of a compact 150Khz antenna?
>>>>
>
> . . . snippity snip . . .
>
>>
>> Back at the university I always wondered about that: Immature fields 
>> (near field), juvenile fields, adolescent fields? So where does an EM 
>> field reach puberty?
>>
>> :-)
>>
>> -- 
>> SCNR, Joerg
>
>
> John Kraus gave a workable definition in his book 'Antennas', that the 
> [appropriately] normalised magnitudes of the different field components 
> (reactive and radiation) are all equal to pi at a distance lambda/2.pi 
> away from the 'antenna' so, closer than that, the 1/r^2 and 1/r^3
reactive 
> terms dominate, and further away the 1/r radiation terms dominate.
>
> So the larger value of lambda/2.pi can be taken as the bare minimum 
> separation of two simple antennas intended to operate independently.  Of

> course, there will still be major coupling between them on account of 
> radiation (TX) or re-radiation (RX) and gainful antennas demand 
> pro****tionately more separation in their line(s) of fire.
>
> Chris

PS: That final statement is 'in practice' in respect of coupling, of
course. 
The mechanisms that give rise to directivity for the radiation field are 
likely to affect the reactive fields in a similar way at small distances.