Reply
 
LinkBack Thread Tools Search this Thread Display Modes
  #1   Report Post  
Old July 5th 08, 07:10 PM posted to rec.radio.amateur.antenna
external usenet poster
 
First recorded activity by RadioBanter: Jul 2006
Posts: 588
Default Radiation and dummy loads

Art wrote:
"The computer program is built on those mathematics, and an antenna
program will ALLWAYS produce radiators in equalibrium which means at an
angle."

Arnold B. Bailey disagrees in "TV and Other Receiving Antennas". On page
367 he writes:
"The directional action of a rod antenna best can be analyzed by
considering the rod as consisting of many tiny sections, connected
together to form a metallic circuit. A typical small segment X - X is
shown in Fig. 7-28 B; its position in a half-wave center-fed antenna is
indicated in part (A) of the figure. Each tiny section may be taken
sufficiently short compared to a wavelength so that the electromagnetic
wave acts practically instantaneously throughout one section, and hence
induces a substantially uniform current in that section. Such a short
antenna segment has a simple directional response pattern, indicated in
Fig. 7-28B, which is basic for all directivity calculations, since all
antenns may be considered to be made up of these tiny segments. This
fundamental response pattern varies as the cosine of the angle (which we
shall call theta) between the direction of the incoming wave and the
perpendicular through the center of the segment X - X, as indicated in
part (B) of the figure. If E stands for the value of the field intensity
(strength of the electric vector), then we can characterize the
directional response by the relation Ecos theta, which gives us the
relative magnitude of E for any wave direction relative to the antenna."

You probably have seen the figure-eight pattern of a dipole antenna and
are already aware that maximum response is broadside to the antenna at
its center. If the antenna is tilted away from the perpendicular its
response is diminished. Other antennas have a similar response as all
are made up of elemental segments.

Best regards, Richard Harrison, KB5WZI

  #2   Report Post  
Old July 5th 08, 08:12 PM posted to rec.radio.amateur.antenna
external usenet poster
 
First recorded activity by RadioBanter: Mar 2008
Posts: 1,339
Default Radiation and dummy loads

On Jul 5, 1:10 pm, (Richard Harrison) wrote:
Art wrote:

"The computer program is built on those mathematics, and an antenna
program will ALLWAYS produce radiators in equalibrium which means at an
angle."

Arnold B. Bailey disagrees in "TV and Other Receiving Antennas". On page367 he writes:

"The directional action of a rod antenna best can be analyzed by
considering the rod as consisting of many tiny sections, connected
together to form a metallic circuit. A typical small segment X - X is
shown in Fig. 7-28 B; its position in a half-wave center-fed antenna is
indicated in part (A) of the figure. Each tiny section may be taken
sufficiently short compared to a wavelength so that the electromagnetic
wave acts practically instantaneously throughout one section, and hence
induces a substantially uniform current in that section. Such a short
antenna segment has a simple directional response pattern, indicated in
Fig. 7-28B, which is basic for all directivity calculations, since all
antenns may be considered to be made up of these tiny segments. This
fundamental response pattern varies as the cosine of the angle (which we
shall call theta) between the direction of the incoming wave and the
perpendicular through the center of the segment X - X, as indicated in
part (B) of the figure. If E stands for the value of the field intensity
(strength of the electric vector), then we can characterize the
directional response by the relation Ecos theta, which gives us the
relative magnitude of E for any wave direction relative to the antenna."

You probably have seen the figure-eight pattern of a dipole antenna and
are already aware that maximum response is broadside to the antenna at
its center. If the antenna is tilted away from the perpendicular its
response is diminished. Other antennas have a similar response as all
are made up of elemental segments.

Best regards, Richard Harrison, KB5WZI


Richard, I understand where you are coming from since all these books
say the same thing. This says that the majority wins and thus is all
known. Well I disagree with that philosophy but I reckonise it. So I
am pushing my findings until I Art Unwin comes to rest with a
majoritory. Since I have an antenna that duplicates those facts I can
only hope that Industry sees something that they want since money in
this world is the driving force.
I am thinking of placing a sample of a tipped antenna on m y page b ut
I fear that all will then blaime the computor program and or Maxwells
laws. You just can't make horses drink!
Art
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
Dummy Loads, 900 mhz Isolators, 30 DB isolation ports [email protected] Swap 0 December 3rd 07 02:55 PM
Reflection on Resistive loads palaniappan chellappan Antenna 23 August 1st 06 09:49 PM
Checkin' out dummy loads with a VNA... [email protected] Homebrew 12 May 1st 06 12:40 PM
bunch of dummy loads and connectors FS 3.00 each Dcaptain Swap 0 November 8th 03 06:37 PM
Oil for dummy loads Javier Henderson Antenna 33 August 20th 03 08:16 PM


All times are GMT +1. The time now is 06:25 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