omnidirectional vs. directional TV/FM antenna
Daniel
Shack VU-90XR VHF/UHF/ FM Antenna 150-2152).
While it has improved the reception of several TV and radio stations
immensely, it also significantly degraded some stations that I used to
receive very nicely with an internal (rabbit-ear) antenna.
Theoretically, the new (directional) antenna should have improved the
receptions of ALL stations **if** I used a rotator to aim the antenna
at the right direction (or am I wrong?). However, since my attic space
constraints don't allow for rotating the antenna, I just placed it at
a fixed direction, hoping for a "best compromise".
But I am not to happy with the current solution. I can, of course, use
an A/B switch to toggle between this attic antenna and a rabbit-ear
antenna, but it's not very convenient and I'd rather have a single
antenna that receives all stations adequately.
Could an omni-directional antenna be a solution? What about placing
*another* directional antenna (aiming to a different direction) and
combining the signal with the first one?
Any tip or help to an absolute layman in this field (me) would be
greatly appreciated.
Thanks,
Daniel
, Bill
>
> Theoretically, the new (directional) antenna should have improved the
> receptions of ALL stations **if** I used a rotator to aim the antenna
> at the right direction (or am I wrong?).
You are correct.
> Could an omni-directional antenna be a solution? What about placing
> *another* directional antenna (aiming to a different direction) and
> combining the signal with the first one?
Yes to both. Those flying-saucer looking disc antennas are pretty good
for omni-directional reception.
--
Bill M
Vieques, PR
Roy Lewallen
The problem with an omnidirectional antenna is that it'll also receive
signals reflected from other objects. The reflections are delayed
relative to the direct signal, so they're shifted on the screen and
appear as "ghosts". I live in a hilly area where the TV signals are very
strong. Here, a directional antenna is necessary, not for gain, but to
reduce ghosting, and the best solution would be to combine two
directional antennas (using a combiner you can get at Radio Shack or
most drug stores). An omnidirectional antenna might work for you, but if
you do see ghosts, the solution is either a rotatable directional
antenna or combined fixed directional antennas.
Roy Lewallen, W7EL
Daniel
antenna (i.e. make and model)? I remember seeing one advertised on the
web, but I don't have the URL anymore. Also, I think that what I saw
wasn't an omni-directional but rather a directional one that rotates
within the enclosing "flying saucer" (I have no idea how such a small
antenna could perform better in the TV frequencies than the
traditional huge directional ones).
", Bill" <"take out the NO in the reply to address"@coqui.net> wrote in message news:<3B94ED25...@coqui.net>...
, Bill
>
> Thanks, Bill. Can you recommend such a flying-saucer looking disc
> antenna (i.e. make and model)? I remember seeing one advertised on the
> web, but I don't have the URL anymore. Also, I think that what I saw
> wasn't an omni-directional but rather a directional one that rotates
> within the enclosing "flying saucer" (I have no idea how such a small
> antenna could perform better in the TV frequencies than the
> traditional huge directional ones).
I hesitate to name any certain brand as being superior. I've seen them
labelled as RCA, Winegard, Channel Master, etc and for all I know, they
may be the same thing with different labels.
Ebay is overflowing with them and most anywhere that sells electronic/TV
gadgetry would have them.
Part of the deal is that they usually have a pre-amp built in and will
automatically seem 'hotter' than some other antennas...of course a
full-size rotatable directional antenna with preamp would be better
still!
Several of my neighbors have these things and they perform better
overall than my medium-sized fixed directional antenna. When my rickety
mess blows down again, I plan to purchase one.
One can assume that the thing is effective across the entire VHF, UHF
spectrum as are most TV amps and devices these days.
Given the situation you have, I think its certainly worth a try.
Good luck.
Crazy George
Using band pass couplers can get you in as much trouble as an
omnidirectional antenna. I used to use Jerrold and other brands of channel
insert networks to keep unwanted signals (reflections) out. These days,
however, all my sources have gone out of business. Who supplies this type
item to the cable companies? I need a couple of new ones for new stations
which have come on the air, and no longer know where to find them.
Daniel:
Either use individual antennas tuned to each channel of interest, or use
traps to filter out the unwanted channels from wide band antennas, or you
will have ghosts and other problems. It might be possible to find an
orientation where the set-up you now have works, but it would require
rotating the antenna in small (~ 3 degree) increments through 360 degrees to
see if there is a orientation which provides an acceptable picture on all
channels. Your antenna has peaks and nulls in the pattern, and the gain
figure applies only off the front end of the antenna, and a few degrees
either side of boresight. All other directions are unspecified, and may
have 20 dB or more loss compared to a reference dipole.
--
Crazy George
Remove NO & SPAM from automatic address when replying directly.
Roy Lewallen <w7...@eznec.com> wrote in message
news:3B9504C1...@eznec.com...
, Bill
>
> Roy:
>
> Using band pass couplers can get you in as much trouble as an
> omnidirectional antenna. I used to use Jerrold and other brands of channel
> insert networks to keep unwanted signals (reflections) out. These days,
> however, all my sources have gone out of business. Who supplies this type
> item to the cable companies? I need a couple of new ones for new stations
> which have come on the air, and no longer know where to find them.
Hey George.
I work in cable and these gadgets are still available, but few and far
between...its a pretty small market. What is available off the shelf is
typically of zero quality unless you are mixing/inserting extreme
channels like 2 and 13 and then you rarely need it anyway.
There's one 5 channel tunable bandpass mixer still being sold by
MATV/CATV vendors but its VHF only.
In cable we don't use these things because its simpler and much better
just to add a separate antenna...or simply to let the individual channel
processors deal with the selectivity.
Bill M
Vieques, PR
Crazy George
which seem to all be made by the same manufacturer in the far east. The
preamplifier oscillates at a frequency very near one of the GPS channels.
There have been several documented cases of them shutting down GPS use for a
several mile radius. They drift so much that they are difficult to pin
down, but several have now been caught in the act. The FCC and FAA are on
the case, for what it is worth.
--
Crazy George
Remove NO & SPAM from automatic address when replying directly.
, Bill <"take out the NO in the reply to address"@coqui.net> wrote in
message news:3B9549C6...@coqui.net...
Crazy George
An example of my problem is this: Ch. 54 weak, but only 20 degrees off the
bearing of 41 and 60. I need to insert a preamp on the 54 antenna, but even
off boresight, 41, 60 and several other channels overload the preamp, even
on a yagi cut for 54. At UHF, narrow band antennas are still many channels
wide.
--
Crazy George
Remove NO & SPAM from automatic address when replying directly.
---Bill---
>
> Bill:
> An example of my problem is this: Ch. 54 weak, but only 20 degrees off the
> bearing of 41 and 60. I need to insert a preamp on the 54 antenna, but even
> off boresight, 41, 60 and several other channels overload the preamp, even
> on a yagi cut for 54. At UHF, narrow band antennas are still many channels
> wide.
My money would still go to a better antenna. We're getting out of the
range of cheap home installations at that point, though.
You could special order a 'sample' BPF from somebody like
Eagle-Comtronics that might give you an additional 20 db rejection of 41
and 60. That may be enough to cure the overload on your existing
preamp. Might cost $20 or so. Another option would be a single channel
pre-amp for 54. Gets kinda pricey ($100+) but they typically do the
job. Blonder-Tongue would be my first choice.
We had a case of trying to receive channel 19 from Columbia, SC 30db
down from a channel 18 in Charlotte even on a 4 foot parabolic antenna.
A good single channel preamp did the job. Straight to a TV you could
hardly discern the 19 video.
Goes to show that it CAN be done...but the price tag isn't always
favorable.