If you have a scientific interest in the physics of the
radio, you should browse this site as an e-book!
The self-antagonist (radiating) systems.
Examples of auto-lesionism! The G5RV is one of
by Francesco Errante
NEVER use a balanced antenna system when the lack of space
compels to operate with radiators (radio-electric transducers)
having their physical length considerably shorter than the wavelength of the radio
signals they are ment to be running on.
That's because, by doing so, it will give origin to self-antagonist
systems and as far as the antenna's gain is concerned, almost nothing else is more
counterproductive than this. So, what is a self-antagonist system ? It is a
system where its radiators are fed in a counterphase arrangement (balanced
systems) while being so close to each other that they can be considered as
two almost conciding point sources (e.g. short center-fed dipoles). Although,
those systems can radiate, their fields tend to cancel each other's effects
out. This is because each of the system radiators generate its own field,
which in turn, at any given point in the space, will induce an electro motive
force equally strong to the one induced by its counterpart but with an
Needlessly to say, that even an array of active and properly resonant full-size
elements or the elements of a Yagi-Uda beam antenna if deliberately mis-spaced would
result in self-antagonist arrangements.
To understand what happens it is useful to know the theory of the point
By applying the theory of the point sources to two short monopoles, in a
center-fed dipole-like counterphase arrangement, therefore ensuring that they
are themselves counterphased with each other, it becomes clear that the
fields generated by their hertzian radiation must have, point by point, an
angular distance which is much less than 180 degrees. Accordingly, a rule of
thumb can be extracted as follows: "the shorter the monopoles, the
smaller the phase difference between the fields generated by them and the
grater is their tendency to cancel each other out".
This phenomenon is called "destructive wave interference".
All the concepts, methods, designs and devices
presented on this web site are the original novelty works of FRANCESCO
3D wave simulator
A simulation of the interference between 2 point
source's field, almost coinciding with each other and fed in a counterphase
arrangement, is easily obtainable by running the java applet associated to this
page, if properly configured, placing the "phase difference" slide in the
middle of its range (180°) and shifting the "source separation" slide towards
left (minimum). Observe how the effects of the two field will cancel each other
NB: The java applet, to which this page refers to,
opens automatically in a new "pop-up" window.
The video below shows the dynamic diagram and
terminates with its rotation in the space
It is a simulator that shows waves in three dimensions. It
can show point sources, line sources, plane waves and interference between
When the applet starts up you will see red and green waves emanating from two
sources in the center of a cubic box. The wave color indicates the fields'
magnitude. The green areas are negative and the red areas are positive.
To get started with the applet, just go through the items in the Setup menu in
the upper right.
Rotate the box with the mouse to view it from different angles.
Material is governed by the Copyright, Designs and Patent Act.
No reproduction, in whole or in part, without written permission.
Copies of these documents made by electronic or mechanical means, including information storage and retrieval systems, may only be employed for personal use.
All rights reserved.