LinkBack Thread Tools Search this Thread Display Modes
Prev Previous Post   Next Post Next
  #8   Report Post  
Old July 17th 03, 06:02 AM
Tarmo Tammaru
 
Posts: n/a
Default

What might be of interest in this discussion is that after he derives the
impedance of free space, he uses that to find the Radiation Resistance of a
short dipole for dW. Where d is the length of the dipole and W is
wavelength. (I did not want to do Greek letters). He ends up with an
equation of the form

R=377k(d/W)**2 or R=790 (d/W)**2.

As a sanity check let d/W=1/2, which violates the , but still gives a
fairly close answer of 197 Ohms, compared to the actual 168 Ohms. Note that
this is not the same as Feedpoint Resistance because it is not referred to
the current maximum. Kraus does not actually say this, but seems that the
near field would be the mechanism for "matching" this to the far field 377
Ohms. The transmitter only sees the feedpoint, the rest of the universe sees
the whole antenna.

If I interpret it correctly, this 197 (168) Ohms in independent of where you
feed the dipole. Kind of hard to boil several pages into one paragraph,
especially since most of this stuff I haven't seen in decades.

Tam/WB2TT
"Dr. Slick" wrote in message
om...

I don't have that book. What does it say?


Slick



 
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules

Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Conservation of Energy Richard Harrison Antenna 34 July 15th 03 12:19 AM


All times are GMT +1. The time now is 10:48 PM.

Powered by vBulletin® Copyright ©2000 - 2025, Jelsoft Enterprises Ltd.
Copyright ©2004-2025 RadioBanter.
The comments are property of their posters.
 

About Us

"It's about Radio"

 

Copyright © 2017