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  Topic: AC source and unconnected terminals...
tensor20

Replies: 1
Views: 7709

PostForum: Questions Related to Antenna Theory   Posted: Mon Mar 11, 2013 2:53 pm   Subject: AC source and unconnected terminals...
Dear Forum,

I found this pdf article that some of you may find useful:

AC case:
AC current does not need a close path to flow. Circuits involving antennas are an example: they are open circuit ...
  Topic: wi-fi antenna and RF cable loss
tensor20

Replies: 4
Views: 16857

PostForum: Questions Related to Antenna Theory   Posted: Thu Apr 26, 2012 6:55 pm   Subject: wi-fi antenna and RF cable loss
Sorry for the confusion:

so I have a single computer. An ISP is broadcasting, from 4 miles away, a wi-fi signal, to my town.
I am trying to understand what equipment I would need to catch that wi ...
  Topic: Reflection off a perfect conducting antenna....
tensor20

Replies: 2
Views: 9769

PostForum: Questions Related to Antenna Theory   Posted: Thu Apr 26, 2012 6:51 pm   Subject: Reflection off a perfect conducting antenna....
I see, thanks Schubert!

I read a book chapter on Fresnel formulas, with reflectivity and transmissivity, and the interface air-perfect metal is discussed.
An incident field gets completely reflect ...
  Topic: Reflection off a perfect conducting antenna....
tensor20

Replies: 2
Views: 9769

PostForum: Questions Related to Antenna Theory   Posted: Thu Apr 26, 2012 1:52 pm   Subject: Reflection off a perfect conducting antenna....
I am reviewing some EM theory for my final exams: Fresnel formulas for reflection and transmission off interface.
If the interface is between air and a pure, perfect metal, perfect reflection of all ...
  Topic: wi-fi antenna and RF cable loss
tensor20

Replies: 4
Views: 16857

PostForum: Questions Related to Antenna Theory   Posted: Thu Apr 26, 2012 1:37 pm   Subject: wi-fi antenna and RF cable loss
Thanks Schubert!

This is my scenario: there is an ISP that is sending a wi-fi signal towards my small town. The distance is about 3, 4 miles....
I am planning to place a wi-fi antenna on the roof ...
  Topic: wi-fi antenna and RF cable loss
tensor20

Replies: 4
Views: 16857

PostForum: Questions Related to Antenna Theory   Posted: Wed Apr 25, 2012 5:15 pm   Subject: wi-fi antenna and RF cable loss
RF cables suffer attenuations of various types. I was reading about wi-fi antennas, which work on the 2.4 GHz frequency. An RF coaxial cable connected to the antenna can have a maximum length of about ...
  Topic: antenna impedance and reactive fieldL are they related?
tensor20

Replies: 7
Views: 16582

PostForum: Questions Related to Antenna Theory   Posted: Sat Sep 03, 2011 3:14 pm   Subject: antenna impedance and reactive fieldL are they related?
hello,

I guess I am not trying to show much. I can show other references supporting the same ideas. Sure the word choice is not optimal.

The ratio of medium parameters epsilon/mu coincides with ...
  Topic: antenna impedance and reactive fieldL are they related?
tensor20

Replies: 7
Views: 16582

PostForum: Questions Related to Antenna Theory   Posted: Fri Sep 02, 2011 10:50 am   Subject: antenna impedance and reactive fieldL are they related?
Hi Schubert,
Check out this link:

www.micronix-jp.com/english/Products/Product%20list/emc.eng.pdf

and look at figure two. I can provide you with other references....
  Topic: antenna impedance and reactive fieldL are they related?
tensor20

Replies: 7
Views: 16582

PostForum: Questions Related to Antenna Theory   Posted: Fri Sep 02, 2011 1:45 am   Subject: antenna impedance and reactive fieldL are they related?
Not true Smile
I have some reliable sources.
Within a distance of lambda from an antenna there is the reactive field where the ratio between the magnitude of the E field to the B field is a number dif ...
  Topic: antenna impedance and reactive fieldL are they related?
tensor20

Replies: 7
Views: 16582

PostForum: Questions Related to Antenna Theory   Posted: Thu Sep 01, 2011 11:00 pm   Subject: antenna impedance and reactive fieldL are they related?
Hello Forum,

When we discuss the impedance of the reactive field we mean the ratio E/H (between the magnitudes of the two fields) close to the antenna, in free space and not the impedance of the a ...
  Topic: Balun Tutorial on Antenna Theory Forum
tensor20

Replies: 4
Views: 15270

PostForum: Questions Related to Antenna Theory   Posted: Sun Aug 21, 2011 1:56 am   Subject: Balun Tutorial on Antenna Theory Forum
Thanks BigSteve,

I am starting to understand. What confuses me

In a coaxial cable there is one current, I1, flowing on the surface of the inner conductor and there is a a current I2 (same mag ...
  Topic: Balun Tutorial on Antenna Theory Forum
tensor20

Replies: 4
Views: 15270

PostForum: Questions Related to Antenna Theory   Posted: Sun Aug 21, 2011 1:52 am   Subject: Balun Tutorial on Antenna Theory Forum
Thanks BigSteve,

I am starting to understand. What confuses me

In a coaxial cable there is one current, I1, flowing on the surface of the inner conductor and there is a a current I2 (same mag ...
  Topic: Balun Tutorial on Antenna Theory Forum
tensor20

Replies: 4
Views: 15270

PostForum: Questions Related to Antenna Theory   Posted: Sat Aug 20, 2011 8:17 pm   Subject: Balun Tutorial on Antenna Theory Forum
Hello Forum,
there is a great tutorial on baluns at http://www.antenna-theory.com/definitions/balun.php

Check it out.
I am not clear why, once the current IB reaches the end of the arm of the di ...
  Topic: Spiral Antennas
tensor20

Replies: 4
Views: 23564

PostForum: News   Posted: Tue Aug 02, 2011 2:38 pm   Subject: current distribution
Hello,

the spiral antenna is a traveling wave antenna. Thanks for the posts. I will study them in detail.

I have a trivial question: in the short dipole (L<<lambda)
the current distributi ...
  Topic: Frequency Independent Antennas
tensor20

Replies: 3
Views: 13601

PostForum: Questions Related to Antenna Theory   Posted: Wed Jul 13, 2011 2:28 am   Subject: Frequency Independent Antennas
Hi BigSteve,

thanks for your reply. But let me understand things even better:

as the frequencies goes up consecutive wraps of the spiral cancel out....
why? So if we start from the center and g ...
 
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