Aside from choosing your HDTV set itself, choosing the right HDTV antenna is the most important decision you're going to make in relation to watching HDTV. Even if you watch most of your HDTV on cable or satellite, you should still invest in a good antenna. Why? Well, there are two key reasons.

1. Cable and satellite operators don't distribute all the available free-to-air HDTV channels. In particular, many local free HDTV channels aren't carried on cable or satellite. So to watch these, you'll need an HDTV antenna.

2. Even where cable and satellite channels do carry free-to-air HDTV channels, they are often highly compressed and this can have a noticeably detrimental effect on picture quality. In most cases, the picture quality of an off-air HDTV signal will be better than a cable or satellite equivalent.

So, now that you know why you should get an HDTV antenna, the next, obvious, question is which one should you get? There are two types of antenna indoor and outdoor just like conventional TV. As with conventional TV, you should always, if possible, opt for an outdoor HDTV antenna. They are simply much better at picking up signals. However, in cases where this isn't possible, for example, if you live in an apartment block or have a landlord who won't let you stick anything on the roof, an indoor antenna will do a reasonable job.

HDTV signals are different from analog TV signals in that, because they're digital, you either get them or you don't. There's no middle-ground of ghosting pictures or snowy screens.

If you're fortunate enough to be able to install an antenna on your roof, you then need to decide which one. Unfortunately, there's no hard and fast rule or quick answer to that one. It depends on where you live, the distance you are from the nearest transmitter and the frequency of the channels you want to receive.

Help is at hand however, in the form of the Consumer Electronics Association and its Antennaweb.org website. Its mapping system allows you to plug in your address and details of your property, such as the number of storeys, and whether there are any likely obstructions like electricity pylons nearby, and based on that gives you details of which HDTV antenna best suits your needs.

With that information at hand, all that's left is to buy the antenna in question, install it and start enjoying all those HDTV stations you never knew existed.