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Re: Cross Boom (Long)

on 3/7/03 8:22 PM, Gary "Joe" Mayfield at gary_mayfield@hotmail.com wrote:

> 2. Another way to look at it.  Suppose I have two separate vertically
> polarized yagi antennas.  It is generally accepted that I can mount them
> together with a steel cross peace and they will work fine (many antennas are
> 'stacked' this way).


This is an EXCELLENT way of looking at things.

The facts are that you can make a CP far field by using two physically
separated and properly phase linear antennas.  But if you stand directly in
front of each antenna, the field is not circular - it's linear.  Only when
you are some wavelengths away from the antenna does the field become

The only difference as you have pointed out is that in a cross element Yagi,
the horizontal separation between the two antennas is zero.  But in
mathematics in order for something to be true in one case, it has to be true
in all cases.

It's very easy to assume the motor example but it just is not the way the
near field of an antenna operates.

Good job, Joe!



Jon Ogden
NA9D (ex: KE9NA)

Citizen of the People's Democratic Republik of Illinois

Life Member: ARRL, NRA
Member:  AMSAT, DXCC

http://www.qsl.net/na9d   <- Updated on 1/22/03!!!

"A life lived in fear is a life half lived."

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