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What reflector to use
and when ? A reflector can
add considerable gain to the 4 bay antenna many times adding as much as
4db of gain. Reflectors can also cut unwanted signals from entering
from the side or rear of the antenna. If you need reception mainly from
one direction or need maximum gain a reflector is needed.
The reflector helps add gain
mainly for 2 reasons
(1) The reflector reflects the TV signal back to the antenna elements
which reinforces the signal already being received.
(2) The reflector generally improves the impedance of the antenna which
creates a better match to the 300 ohm balun or feed line which
increases energy transfer.
Without a reflector these antennas will give a bi-directional reception
pattern with even reception each way and considerably less off of the
sides. This is great for someone between 2 TV markets with fairly
strong signals reliable UHF reception can be in the 30-50 mile range
for a 4 bay depending on antenna placement, surroundings and terrain.
The curved or angled oversize reflector along with swept forward whisker elements can help
narrow the beam width of the antenna by squeezing the gain more
in the forward direction and less on the sides and rear. This reflector
also works well to enhance VHF-hi channel 7-13 reception. With this
style reflector on a 4 bay UHF reception in the 60-80
mile range can be normal depending
on antenna placement, surroundings and terrain.
Reflectors less than 34" wide don't work well for all the VHF-hi
channels 7-13 but work fine for UHF. The narrower reflectors won't get
as much advantage of the curve or angle and the narrowing effects of
the forward beam but still give a good boost.
About anything metal will make a reflector in general
larger diameter tubing or strips of flat stock can be spaced further
apart and still achieve good rear rejection as compared to wire. Even
good old aluminum / Tin foil strips running horizontally on a piece of
cardboard will do the trick.
The key to a good reflector is the spacing between the horizontal
running elements within the reflector and to make it the right width
for the desired channels.
The vertical spacing of the elements has more to do with rejection of
unwanted signals then gain. Good gain can be achieved on UHF with
elements spaced as far as 4" apart and 2" is the point where forward
gain isn't enhanced much if any. Rear rejection will still get better
down to about 1" spacing but after that not much is gained. Wire fence makes an excellent
reflector material 2" x 4" wire fence is a good choice for both
rejection, forward gain, and wind loading. 1" x 2" fencing is even
better for rear rejection on the upper UHF channels but does little for
VHF-hi. Hardware cloth can make a good reflector but needs more support
to keep it in place and if used outdoors the wind loading becomes an
issue. I've used both tubing and wire fence with good
Many times wire fence scraps can be found from a left over
fencing job and old VHF antennas make a great source of tubing for
I now have a reflector
mounting Kit available which makes mounting the reflector and the
whole antenna much easier