Re: What tricks do Aerial riggers employ to overcome tree based notch filters?
- From: "Brian Gaff" <Briang1@xxxxxxxxxxxxxxxx>
- Date: Thu, 23 Jul 2009 21:26:44 GMT
On a very scientific note, there was something about making materials with
strange refractive indices at certain frequencies. The military use them to
disguise things from radar, but this sounds like exactl what you need to
bend the signals around the trees.. grin.
Brian
--
Brian Gaff....Note, this account does not accept Bcc: email.
graphics are great, but the blind can't hear them
Email: briang1@xxxxxxxxxxxxxxxx
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"-<GB>-Carpy" <carpy@xxxxxxxxxxxx> wrote in message
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"Stephen" <i.want.spam@xxxxxxxx> wrote in message
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I have a row of very tall trees at the bottom of my garden that are acting
as a deep notch filter at around Ch 42 and Ch 43. They are at least 20m
high.
The trees have preservation orders on them so applying an axe or pruning
them to them is *not* an option and the land the trees grow on is owned
jointly by the police and fire services.....
I have already tried different length poles (3m, 4.5m and 6m) to allow me
to move said aerial up and down vertically but it does not move the
frequency of the deep "notch" to a frequency below UHF40 or above UHF 46
and not at UHF 67 either.. (Sandy Heath DTT, 40, 42,43,45,46 and 67, not
interested in analogue, only digital. The results are the same whether I
use a log periodic or a Triax Unix 52,
I have a phased pair of log periodics to deal with Sutton Coldfield's
analogue stamping on Sandy Heath's digital Muxes (Thank you Bill Wright)
Would moving the aerial sideways or moving aerial closer to or further
from the trees work usding a cranked pole? If not, apart from moving
house what other practical options are open to me?
Regards
Stephen
If it's a deep notch (a real pain) and you can't remove it by going down /
up in its current location then you've got to move the aerial. Widgitt has
given some good advice & like he says, there's no subsitution for testing
various different spots to find the best position. Lower can often be
better where trees are concerned. I spent over an hour on that architects
rooftop the other day, trying to find a position where there were no
significant notches. It was completely screened by trees, but I found a
spot in the end. No guarantee it will stay that way though so Freesat etc
can often be the most sensible long term solution.
.
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