As usual, I get great information from this reflector. I still don't know what
I'm going to do, but at least now I have more specific information on which to
base a decision. What will likely do is to leave it at the lower height for
now unless or until I run across the "perfect" telescoping solution. As of
yet, I have not fund such a beast.
Now... for the next question, has anybody tried the Hy-gain telescoping masts?
It looks like the upper sections would be too small, but the bottom 4 sections
might do the trick. Would the sections rattle around a lot when nested and
would it keep the array pointed "North"?
Steve
-------------- Original message --------------
From: jcplatt1@mmm.com
> Hi Steve. Good question, one that we rovers ask a lot. 6m is different
> than the higher bands because is almost HF and because most 6m rover
> antennas are within a wavelength (or closer) to ground, this impacts their
> take-off angle. I fired up EZNEC and using just a simple 6m dipole moved
> it from 13' to 17' to 21' looking at the change in gain at low take-off
> angles (three to five degrees) compared to the model at 13'. At low
> take-off angles, moving the 6m antenna from 13' to 17', all other things
> being equal, equates to a gain increase of about 1.5 dB. Moving the
> dipole from 13' to 21' equates to a gain increase of about 3.7 dB. This is
> solely due to a lowering of the take off angle of the main lobe. My
> thought is that if you can get your 6m rover antenna moved from 13' to 21'
> that you would see some performance improvement, but that the move from 13'
> to 17' would not produce much help. Another thing to think about is a
> "high" dipole, maybe one at 25', in that it may be equal to or better than
> a simple gain antenna mounted at 13' or lower. Mechanically speaking,
> when stopped, it might be easier getting a simple lightweight 6m dipole
> "high" rather than getting a physically bigger gain antenna to 17'.
>
> As a rover, its all a compromise which makes designing rover stations so
> much fun ! On 2m and up its more difficult to say if the slight
> increase in height would be noticable .... higher is always better but the
> improvement may not be as significant as it is on 6m.
>
> Here in MN, the challenge is to get above the July/August corn - with
> ethanol sales way up corn production is way up which is good for farms but
> bad for rovers !
>
> 73, Jon
> W0ZQ/R
> _______________________________________________
> VHFcontesting mailing list
> VHFcontesting@contesting.com
> http://lists.contesting.com/mailman/listinfo/vhfcontesting
_______________________________________________
VHFcontesting mailing list
VHFcontesting@contesting.com
http://lists.contesting.com/mailman/listinfo/vhfcontesting
|