[Antennas] Re:Design questions for directional antennas

[Steve-W0OOW]

The information you seek is most likely in one of the old ARRL antenna
books.  Look under plumber's delight antennas.
73.oow

> 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
> _._ _.