Sirio Vector 4000

Hi Folks,
Just curious if the positioning of the gamma rod would make any difference with regards to pointing North, East, West or South?
Some have said it doesn't matter but I like more opinions on it.

Hi. No idea, never used one. But if I had to put money on it, I would say it would make no difference, or at least not one that anyone would notice.

I bet it does make a little difference as a guess. It a piece of metal that is not symmetrical in the reactive near field (albeit a part of the antenna itself)and that will almost certainly make a small difference. However it is difficult to know for sure whether it will be adding something or taking away.

I have heard the same about matching stubs on GM style antennas but never noticed it myself.

We must recall that conditions are the king maker when it comes to DX.

However I suspect the difference may be unnoticeable. It is a relatively small piece of metal compared to the entire structure of a 8.5m long antenna.

We do know position of antenna with relation to ground plane can and does make a difference for antennas requiring a ground plane... i.e. broadly current fed. (or capacitive reactance at feed point of a 5/8th wave)

A car under a mag mount that does make a difference. And in the past I have oriented a vehicle to face a specific direction when running either whips or 1/4 waves on my car. Forming a little gain in one direction.

That is crudely shown and approximated here. But a vehicle is a BIG chunk of metal and greatly improves performance of a whip.



It's not beam gain but I think you may get 1-3dB in the direction where most ground plane metal is.

i.e. mornings I face east, evenings I would face west following the suns path a little.

I would not sweat it and put it up without worrying.

Have fun with that I would like to try a Vector one day. Back in the day when you saw those you knew it was a serious CB station ! They look the business as well. A real neighbour anxiety inducing antenna.

Cool reply FreqFreak,
I figured the same about the symmetry issues but I guess it would be hard to quantify.

In looking again the size of the gamma match, it is so small compared to the antenna structure and wavelength of operation I suspect it will pale into insignificance.

Have fun with that big ol twig !