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Isotropic probe? - RF Cafe Forums

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Mr.Whatever
 Post subject: Isotropic probe?
Posted: Mon Jan 29, 2007 4:43 pm 
 
Captain
User avatar

Joined: Fri Apr 07, 2006 6:10 pm
Posts: 18
I thought an isotropic antenna is mythical. What is an isotropic probe?

As referred by the following, site: http://www.emctd.com/


 
   
 
nubbage
 Post subject:
Posted: Tue Jan 30, 2007 7:22 am 
 
General
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Joined: Fri Feb 17, 2006 12:07 pm
Posts: 218
Location: London UK
It's possible to synthesize an approximation to an isotropic antenna that is close enough for most measurement purposes over a limited frequency range.
Three bolometers mutually at right angles is one solution that springs to mind. Obviously this will be very insensitive, but it is a three axis RF detector with broad bandwidth, and so fulfills most criteria for an isotropic receiving antenna. But then, it is not a reciprocal device, so cannot be used for transmission.
If you extend this concept to a set of three loops or patches, each having good cross-polar isolation in its own plane, and combine them in a 3-way combiner, you perhaps have a narrow band isotropic radiator and detector.
None of these ideas meets the true full-spectrum reciprocal well-matched antenna necessary to be an isotrpoic radiator. To this extent therefore, the true isotropic radiator is a theoretical concept.


 
   
 
Lens
 Post subject: Re: Isotropic probe?
Posted: Sun Feb 04, 2007 8:50 am 
 
Lieutenant

Joined: Sat Feb 03, 2007 4:13 pm
Posts: 3
Mr.Whatever wrote:
I thought an isotropic antenna is mythical. What is an isotropic probe?
As referred by the following, site: http://www.emctd.com/


Isotropic antenna in theory is a Huygens source with cardiod antenna diagram and directivity 4.77 dBi. It may be two dipoles electrical and magnetic. Magnetic dipole may be a loop or slot.




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