[Hallicrafters] Re: Dipole antenna

[John Webb]

dis-advantage,using a balun offers a antenna for only 1 band.Don't try to 
use a balun for multiband through a tuner...Melted balun is a result...john
----- Original Message ----- 
From: "peter markavage" <manualman at juno.com>
To: <hallicrafters at mailman.qth.net>
Sent: Tuesday, February 22, 2005 7:07 PM
Subject: Re: [Hallicrafters] Re: Dipole antenna


>
> Quote Glen - There have been amateurs who actually noticed a decrease in
> performance by adding a balun.  But, in general, adding a balun will have
> little, if any, effect on the performance.  There are exceptions, of
> course, but I wouldn't go out and purchase a balun to put on a dipole
> type of antenna.
>
> You're right. Adding a balun will have little effect on performance of
> the antenna. If you add one and performance decreases, it's either not a
> 1 to 1 balun or there's something wrong with it. However, the point of
> using a 1 to 1 balun to interface between a coax (unbalanced) feedline
> and a balanced antenna, generally helps performance between rig and
> antenna. Connecting an unbalanced coax feed to a balanced antenna will
> generally cause RF to flow down from one leg of the antenna down the
> shield of the coax. This can cause unwanted radiation of the shield. This
> can also affect your SWR as the coax moves in the wind and maybe comes in
> close proximity to metallic objects. There are several ways to reduce or
> eliminate this type of radiation besides a 1/1 balun including a 1/4 wave
> stub of coax on the shield connected side of the antenna and even looping
> several feet of coax feedline at the antenna input points. Not using a
> balun is not the end of the world, and, as you noted, amateurs have been
> going without them for years. However, having lived in residential areas
> with typical 100 X 100 foot lots my entire amateur career, unintentional
> feedline radiation that might cause interference to TV's telephones and
> other electronic devices, is something I like to keep to a minimum.
>
> More info on this subject can be found in most of the ARRL Antenna Books
> and other antenna reference material.
>
> There ya go Hank, my pitch on antennas 101.
>
> Pete, wa2cwa
>
> On Tue, 22 Feb 2005 15:47:55 -0800 (PST) Glen Zook <gzook at yahoo.com>
> writes:
>> In theory, yes.  In a practical situation, probably
>> not.  Amateurs have been feeding dipoles directly with
>> coax for decades.  Sometimes adding a balun might help
>> slightly in the pattern of the antenna.  However,
>> there are so many objects near most dipoles that
>> distort the pattern that in most cases you would have
>> difficulty measuring the difference let alone noticing
>> any difference in performance.
>>
>> There have been amateurs who actually noticed a
>> decrease in performance by adding a balun.  But, in
>> general, adding a balun will have little, if any,
>> effect on the performance.  There are exceptions, of
>> course, but I wouldn't go out and purchase a balun to
>> put on a dipole type of antenna.
>>
>> Glen, K9STH
>>
>>
>> --- Waldo Magnuson <magnuson at mac.com> wrote:
>>
>> I have a question: My high (75 feet up)  40 meter
>> dipole antenna is connected directly to  a coax (per
>> ARRL handbook) instead of having a balun between the
>> antenna and coax.  I could build (or buy) a 1:1 balun
>> but am I likely to see any difference?
>>
>> =====
>> Glen, K9STH
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