Reply
 
LinkBack Thread Tools Search this Thread Display Modes
  #11   Report Post  
Old July 23rd 03, 07:25 PM
W5DXP
 
Posts: n/a
Default

Nic. Santean wrote:
I did the computations : the composition of those
two "EM emissions" 90 degree out of phase (but
having the same period) leads to a wave of exactly
the same wavelength as the signal applied to the
antenna.

So, there is no contradiction in my scenario so far.


Methinks the situation is a little more complicated than that. The
E-field and H-field is in phase at the feedpoint of a resonant
dipole. In the real world, they are never 90 degrees out of phase,
but they get close to 90 degrees at the points midway between the
feedpoint and the ends of the resonant dipole. The E-field and H-
field are (almost) back in phase at the ends of the dipole.

The ratio of net total voltage to net total current at points along
a dipole can be thought of as a spiral on a Smith Chart. It is much
like a transmission line where the spacing between wires is too large
for the frequency of operation and therefore leaks radiation.
--
73, Cecil http://www.qsl.net/w5dxp



-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
-----== Over 80,000 Newsgroups - 16 Different Servers! =-----
  #12   Report Post  
Old July 23rd 03, 08:47 PM
Nic. Santean
 
Posts: n/a
Default

We are talking about half wavelength dipole antennas, right ?

Nic.

Methinks the situation is a little more complicated than that. The
E-field and H-field is in phase at the feedpoint of a resonant
dipole. In the real world, they are never 90 degrees out of phase,
but they get close to 90 degrees at the points midway between the
feedpoint and the ends of the resonant dipole. The E-field and H-
field are (almost) back in phase at the ends of the dipole.

The ratio of net total voltage to net total current at points along
a dipole can be thought of as a spiral on a Smith Chart. It is much
like a transmission line where the spacing between wires is too large
for the frequency of operation and therefore leaks radiation.



  #13   Report Post  
Old July 23rd 03, 09:16 PM
W5DXP
 
Posts: n/a
Default

Nic. Santean wrote:

We are talking about half wavelength dipole antennas, right ?


Yes. A 1/2WL dipole can be thought of as a very leaky transmission
line. It has standing waves that leak radiation into the Æther. :-) May
I suggest trying to understand traveling-wave antennas before getting
into standing-wave dipoles? Consider a terminated V-beam or terminated
Rhombic to eliminate the confusion associated with reflected waves. But
don't feel bad about confusion associated with reflected waves. Some of
the r.r.a.a gurus don't understand reflected waves and the energy plus
momentum involved in their very existence. So many sacred cows - so
little time. :-)

Methinks the situation is a little more complicated than that. The
E-field and H-field is in phase at the feedpoint of a resonant
dipole. In the real world, they are never 90 degrees out of phase,
but they get close to 90 degrees at the points midway between the
feedpoint and the ends of the resonant dipole. The E-field and H-
field are (almost) back in phase at the ends of the dipole.

The ratio of net total voltage to net total current at points along
a dipole can be thought of as a spiral on a Smith Chart. It is much
like a transmission line where the spacing between wires is too large
for the frequency of operation and therefore leaks radiation.

--
73, Cecil http://www.qsl.net/w5dxp



-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
-----== Over 80,000 Newsgroups - 16 Different Servers! =-----
Reply
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
basic question about radio waves Nic. Santean Antenna 14 July 19th 03 06:47 PM
Amateur Radio Legal Issues List Amateur Radio Station N0JAA Antenna 0 July 19th 03 04:30 AM


All times are GMT +1. The time now is 10:32 AM.

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