[SOC] Balanced vs Unbalanced Antennas

[Jim Reicher, W0HV]

Negative electrons are used only in blacklight bulbs.

73 1/2
Jim
W0HV

-----Original Message-----
From: soc-bounces at mailman.qth.net [mailto:soc-bounces at mailman.qth.net]On
Behalf Of Mike Besemer (WM4B)
Sent: Fri, February 12, 2010 9:18 PM
To: 'Second Class Operators' Club'
Subject: Re: [SOC] Balanced vs Unbalanced Antennas


"The ladder line ensures the positive electrons equal the negative
electrons"

What the heck is a positive electron?

74,

Mike
WM4B
(Decidedly Unbalanced!)

-----Original Message-----
From: soc-bounces at mailman.qth.net [mailto:soc-bounces at mailman.qth.net] On
Behalf Of John Davies
Sent: Friday, February 12, 2010 10:16 PM
To: Second Class Operators' Club
Subject: [SOC] Balanced vs Unbalanced Antennas

Balanced vs Unbalanced Antennas.



Many newcomers to the wonderful world of Amateur Radio ask "what is the
difference between a balanced and an unbalanced antenna?"  I hope the
following explanation will help.



Firstly, a balanced antenna is inherently more stable than it's unbalanced
cousin. It is very hard for a balanced antenna, like a dipole, to fall down,
hence the main reason for the term "balanced". However,  the fundamental
reason why we call a dipole a "balanced" antenna has something to do with
travelling waves in two equal halves. To make it simpler, try to visualize
two water pipes fed from a single standing pipe. The diameter of each pipe
is the same. The device which separates the two pipes equally is often
called, in technical terms, a "balun". This is a very clever thing and we
will not spend too much time discussing it now. Suffice it to say, that it
"separates" both halves of the circuit and looks quite nice too, especially
if it's in a  shiny black box.

Usually we use ladder line from the balun to the feedpoint of the antenna.
Newcomers to the hobby often ask "why is a called a ladder line?" The answer
is quite astonishing really - it actually looks like a ladder if you think
about it! Again, it's a question of visualization. Like Morse code, it will
come to you if you practice this kind of lateral thinking hard enough.

The ladder line ensures the positive electrons equal the negative electrons
on each side. Some really smart Amateur Radio operators use a concept known
as J-notation to calculate the number of travelling waves on each side, and
their force. This is a very tricky concept to grasp for novices, but to make
it simpler I will just say that it involves being able to have the square
root of minus one, which otherwise is very difficult to do. This is why we
use the term "imaginary numbers", because nobody understands it.



Unbalanced antennas, like verticals, on the other hand, only have one pipe
with an outer shield called a coaxial cable. To use the water analogy again,
imagine the water only goes up the central pipe now. Of course, if it goes
too high the antenna will topple over. This is the principal reason why we
use the term "unbalanced" when referring to verticals. It is also the reason
why you must use stays and guys to stop the antenna, which is inherently
unbalanced, from falling down.



Next month we will consider the tricky subject of lightning and why it is
not good for you. Until then feel free to email with any questions.



73


______________________________________________________________
SOC mailing list
Home: http://mailman.qth.net/mailman/listinfo/soc
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:SOC at mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

______________________________________________________________
SOC mailing list
Home: http://mailman.qth.net/mailman/listinfo/soc
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:SOC at mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
No virus found in this incoming message.
Checked by AVG - www.avg.com
Version: 9.0.733 / Virus Database: 271.1.1/2683 - Release Date: 02/12/10
01:35:00