wrote:

I want to install an outdoor antenna for HDTV reception. I live in a
one story home and I am in Santa Clara, CA. Most of the stations are
in SF which is about 40 miles away.

In general, how tall should outdoor antenna be? Can it be just as high
as the peek of the roof? Or does it need to be 5 feet or more above
the roof? Does home depot sells pole/masts that long?

Higher the better, and if you're going to the trouble of mounting one
on the roof, you may as well place it at least 5-8' above the peak..
You want an antenna with a fairly big UHF section (thing at the front
with the short horizontal rods), meaing it should have a reflector
(short horizontal rods that extend above and below the boom). Outdoor
mounting can help a lot, especially for UHF.. Also be sure to
electrically ground the antenna, mast, and antenna cable shield to
your home's ground rod (near the circuit breaker box),. Also install
a spark arrester inline with the cable, and let the cable droop about
a foot where it enters the building so that rain will drip off rather
than run inside. About every TV and video recorder includes basic
instructions about this in the first few pages of the manual, for
safety reasons.

I'd use RG-6QS (QS = quad shield) cable because it doesn't cost that
much more but blocks interference the best. You need special RG-6QS
connectors for it, but you don't need bother with gold plated or
weatherproof stuff. You can make connections watertight with black
vinyl electrical tape (the last few wraps must not be stretched).
Also clamp the cable to the mast so it doesn't tug at its connector.

Buy a reputable brand, like Radio Shack, AntennaCraft, Winegard,
Jerrold, and don't bother with that overpriced Terk junk. Fry's and
radio-tv supply houses have antennas, and some Radio Shack stores may
still have in stock (I bought their second-largest outdoor antenna for
just $5 on close-out). If you have to order by mail, try MCM
Electronics, Dalbani, Premium Parts. I think that San Fransisco uses
a central antenna for almost all the TV stations, so get a directional
antenna, not a unidirectional one. Also a big antenna can alleviate
the need for a distribution amplifier.