Re: Removing reflector from aerial

In message <TcydnQMM9N4rbw7XnZ2dnUVZ8vqdnZ2d@xxxxxxxxx>, Bill Wright <insertmybusinessname@xxxxxxx> writes

The reflectors on most of these 'gimmick' aerials are unnecessarily big. It
would make no difference to anything if they were reduced in element length
to perhaps 350mm. Also, the top and bottom elements are unnecessary. My
objection to removing them though is that the whole aerial will have been
designed empirically (tweaked) so chopping bits off my make the remaining
bits work less than optimally. I have the same objection to removing the
director chain. Possibly this could be corrected by a tiny movement of an
element or an alteration to the balun, but how can we determine that? Or to
be accurate, how can the OP determine that?

All yagis are more dependent on the directors for HF response, and the
broader the bandwidth the more this is true.

What do you think to this:
http://www.wrightsaerials.tv/aerialphotography/modern/061.html

In my ignorance, that aerial looks OK to me - apart from the length of the reflector being a bit on the short side. From what you said a couple of weeks ago, this can cause a sharp roll-off at the LF end. From the small amount of tapering of the directors, I guess the aerial is narrowband (just one group), whereas the choice for a caravan would normally be a wideband aerial.

As for Vet Tech's aerial, surely it doesn't matter if the 'finely honed' gain performance becomes less than optimum when you remove the front half of the boom and cut off the top and bottom halves of the reflector? She's only mile from Crystal Palace.

From what Andy said, the front-end directors won't really affect the gain much at the LF end (where CP is).

From what you are saying above, removing the top and bottom of the reflector (even if it is a mesh, and not multiple individual elements) won't do much either.
--
Ian
.

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