Thread: NVIS and VHF?
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Old May 22nd 11, 11:00 PM posted to rec.radio.amateur.antenna
Wimpie[_2_] Wimpie[_2_] is offline
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First recorded activity by RadioBanter: Mar 2008
Posts: 329
Default NVIS and VHF?

On 22 mayo, 20:04, 'Captain' Kirk DeHaan
wrote:
I'm living in a wooded area and am trying to hit our club repeater
reliably. *It's cloudy now so I'm and getting a bit of ducting but I
have a lot of trees, mostly poplars, in the direct path. *I would have a
line of sight if not for the trees as I'm up enough in altitude. *I can
cut the trees, they're mine, but finding the right ones is difficult and
i don't want to waste the whole grove.

I go from keying the repeater with no intelligible signal to not being
able to hit it. *Today I actually have an S meter reading due to the
clouds. I am currently using a J-pole and will put up a Yagi soon but
wonder if NVIS would work on 2m? *I have only seen references to it
being applied in HF.

'Captain' Kirk DeHaan
N6SXR


Hello,

The repeater antenna will probably have most of its radiation in the
horizontal plane and 145 MHz is far above the critical frequency, so
your rays will leave earth.

Did you monitor the signal for several time (also winter and rain) to
assess the real influence of the trees? Do you have any possibility to
move the J-pole to another place?

As you can open the repeater now and then, some 10 dB additional gain
will certainly help you to get above the FM-knee (assuming that you
can get the beam at same height as the J-pole. Nice thing is, it will
also improve reception.

With kind regards,

Wim
PA3DJS
www.tetech.nl
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