[Antennas] Design questions for directional antennas

[A10382]

I've made a few homebrew directional antennas over the years.  In some
cases, I merely followed a design in a magazine article.  In a few
cases, I measured and copied a commercial antenna.  While all but one of
these antennas worked fairly well, some questions nag at me:

1) Some yagis have their non-radiating elements electrically connected
to the boom (and therefore each other).  I copied a Cushcraft 900 yagi
(with a metal boom), but made the boom on mine out of wood (using the
same diameter and length radiators for all elements).  I did not connect
the non-radiating elements - the directors and the reflector -- to each
other.  While I did not notice any difference in performance between the
two, I also do not have an antenna range to verify exact performance,
alternatively relying on just operating.

Q1: Is there any effect on performance by either connecting/grounding
the non-radiating elements ??

2) Commercially made broadcast TV receiving antennas usually have their
elements in a "V" shape (sort of like a horizontal inverted V).

Q2a: Other than possibly cosmetics (the antenna 'pointed' at the
station) is there a design/performance reason for this ??
Q2b"  Does this "V" shape have any effect on element length or bandwidth
?

3) A dual band yagi design like the 'Arrow' handheld has the elements
for the 2 bands at right angles to each other.

Q3:Does this type of element positioning eliminate any effect one band's
elements has on the other band ?

BTW: The one design that did not work well nagged me.  I ended up
following a few suggestions, and the performance eventually (and
seemingly) closely equaled the original design.  The change with the
most impact was replacing stainless elements with aluminum (the original
design was made with aluminum) - go figure...

======
Frank
_._ _.







-- 
No virus found in this outgoing message.
Checked by AVG Anti-Virus.
Version: 7.0.338 / Virus Database: 267.9.7/60 - Release Date: 7/28/05