Bad reception: a TV antenna FAQ

You may have the newest, shiniest television on your street, but it will be all for nought, if you can't receive free-to-air digital TV.

You may have the newest, shiniest television on your street, but it will be all for nought, if you can't receive free-to-air digital TV.

If your home is wired up to Foxtel or Austar, don't think that this guide doesn't apply to you. Depending on where you live, and how you receive pay TV (cable or satellite), free-to-air channels may not all be retransmitted. So, without free-to-air reception, you might be missing out on Formula One racing, The Voice or other free-TV programming that you just can't live without.

But before we talk about free-to-air TV reception, let's step back to the very beginning...

What is an antenna?

TV, radio, Wi-Fi and mobile phones all work by receiving (and, in the case of mobile phones and Wi-Fi equipment, also transmitting) electromagnetic waves at particular frequencies. To pick up the signals, these devices require a transducer or an antenna calibrated to pick up a certain range of frequencies.

Can I have one antenna to rule them all?

Unfortunately not. Put simply, the metal rod or wire inside an antenna has to be the same length (or a simple fraction thereof) as the wavelength of the signal that you're trying to pick up.

That's why when you set up a hi-fi system, there are two separate antennas that need to be plugged in: one for AM, and one for FM.

What's the frequency, Kenneth?

The table below lists some frequencies that we utilise on a daily basis.

  Frequency
AM radio 520kHz to 1610kHz
FM radio 87.5MHz to 108.0MHz
Telstra Next-G 850MHz
GSM 900MHz and 1800MHz
3G 2100MHz
Visible light 400THz to 790THz
X-rays 30 petahertz to 30 exahertz

What about television?

Analog VHF 64.25MHz to 143.75MHz,
and 175.25MHz to 228.75MHz
Analog UHF 478.25MHz to 819.75MHz
Digital VHF 175.25MHz to 228.75MHz
Digital UHF 520.25MHz to 819.75MHz

Notice how the low analog VHF band overlaps with the FM radio range? In the good ol' days, you could drive around parts of country Australia and listen to TV on your car radio, as certain country TV stations were allocated frequencies in the FM band.

Is there such a thing as a digital antenna?

The short answer is no.

The slightly longer answer is that changing your antenna may help with any digital TV-reception issues.

As you can see in the table above, the frequencies used for digital TV are a subset of those used for analog TV transmission. This means that many existing antennas should have no problems with receiving digital TV signals.

Older antennas, however, may only be designed to pick up a limited range of frequencies. Thanks to channel reassignments, channel allocations for digital transmission and newly available stations, TV stations broadcasting in your area may now fall outside of your antenna's working frequencies.

What's the ideal location for a TV antenna?

On the roof, with a clear line of sight towards your nearest TV-transmission tower, is always the best policy.

If you live close to a tower, you may be able to get away with an antenna located in the space under your roof or in your living room. Do be aware that many materials used in buildings will reflect electromagnetic waves, so you need to be in a good spot for this set-up to work well.

To find out where your nearest towers are, go to the My Switch section of the Federal Government's Digital Ready website, enter your address, zoom the map out and check out the More Information tab.

What external factors affect my TV reception?

Your location plays a big part. Naturally, the farther away from the TV tower you are, the weaker the signal will be. If you live in a valley, a depression, next to a cliff or are surrounded by taller buildings, your reception will be hampered, as electromagnetic waves are bounced or absorbed by these natural and man-made features.

To a lesser degree, the climate and atmosphere also play a role, with inclement or severe weather able to hinder signal transmission. If the weather gods play their cards right, though, it's possible to (faintly) receive analog TV transmission from Melbourne in Sydney.

Another minor player is one of the after effects of the Big Bang. There's a small amount of leftover heat from this universe-creating explosion that permeates through everything, and it interferes with all broadcasts in the form of cosmic microwave background radiation. You can see it most clearly if you flick to any analog channel that doesn't have a TV channel transmitting on it.

I have problems receiving digital TV; what should I do?

It mightn't be the cheapest option, but the easiest solution is to call a local antenna expert, have them inspect your place and go on from there.

If you don't want to go down that route, then you can check out the specifications for your antenna to see whether it operates in the same range as the TV stations in your area. You can find a full list of digital TV channel allocations on the Australian Communications and Media Authority's (ACMA) website, and cross-reference them against the channel frequencies on this website.

Should your antenna not cover the frequencies used in your area, then it's time to buy one that does. Don't forget to be careful when you're up on the roof installing your new pride and joy, but, just as importantly, don't forget to point your new aerial in the direction of your nearest or best transmitter tower. The My Switch section of the Digital Ready website should give you a good idea of which way your new antenna should face.

I've replaced my aerial, but reception is still patchy

If you've got a correctly specified antenna, then the problem most likely lies elsewhere. For example, the wiring inside your house could be old and worn out, and lack the appropriate shielding, or you may require a booster box. At this stage, you should probably bite the bullet and call in an expert to help you out.

About the author

Derek loves nothing more than punching a remote location into a GPS, queuing up some music and heading out on a long drive, so it's a good thing he's in charge of CNET Australia's Car Tech channel.

 

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