How do you improve HDTV reception?

Put up a decent antenna on the roof, and run decent 75-ohm coax to
your TV. Antenna height helps a lot. So does aiming the antenna
towards the transmitters (this may require a rotator, or an
electrically-steerable antenna in some places, if the TV transmitters
aren't all in roughly the same direction).

If you can't put an antenna on your roof, you might be able to put one
in the attic.

I'm using a Supersonic portbale with an antenna tha came with
a USB TV receiver. I can't even find a decent cheap antenna.

What you need, in terms of an antenna, depends quite a lot on where
you are.

In some areas, a UHF-only antenna is adequate. Take a look at
http://www.tvantennaplans.com/ - there are plans for a home-built
Gray-Hoverman DB4 antenna design you can make yourself.

http://www.digitalhome.ca/forum/showthread.php?t=81982 has boatloads
of additional information, including several design variations.

If your area still carries digital TV on some of the VHF frequencies,
you may need more than this. The old-standard analog-TV roof antenna
(which covers VHF low band, VHF high band, and UHF) will almost always
work fine for HDTV.

If you've got a big roof with lots of room, want a "stealthy" antenna
that the neighbors don't see or complain about, and the TV
transmitters are mostly in one direction, consider putting up a
"terminated rhombic"... it's just four pieces of wire in a diamond
shape, with the feedline at the "away from the transmitters" end, and
a resistor at the "towards the transmitters" end.

Remove the resistor and short the ends together, (or leave 'em open)
and you end up with an unterminated rhombic, which will receive
signals well from both directions (but not from off to the side).

--
Dave Platt AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
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