How does a TV aerial work?

Wednesday 22nd July 2009
Submitted by Gareth Mitchell
Brian Newlove, Cottingham

Like any antenna, a TV aerial is made of metal. Electromagnetic waves carrying television signals induce tiny electrical currents in the antenna. The television set amplifies the signal and selects the information that carries vision and sound. Engineers refer to TV aerials as 'yagi arrays'. The metal plate at the array's far end reflects the signal back down its length. The parallel rod-like structures that run along the length of the aerial are specially spaced to optimise signal strength.

Why does a windscreen crack in a zig-zag?
previous qanda Article
Why can't I recycle takeaway pizza cartons?
next qanda Article
Q&A Tabs

It’s not just humans that enjoy a smooch; lots of animals have courtship behaviours involving the mouth. Pigeons touch beaks, cats and dogs nuzzle each other, male fruit flies lick the...

Phlegm is the mucous secretion of the respiratory passages. The cilia cells that line these passages are continually driving the phlegm upward to the throat, where it triggers the swallow reflex...

Lobsters and other shellfish have harmful bacteria naturally present in their flesh. Once the lobster is dead, these bacteria can rapidly multiply and release toxins that may not be destroyed by...

It depends on how high (or low) you set the bar of fluency. Ziad Fazah, born in Liberia, brought up in Beirut and now living in Brazil, claims to be the world's greatest living polyglot, with...

Trees release oxygen when they use energy from sunlight to make glucose from carbon dioxide and water. Like all plants, trees also use oxygen when they split glucose back down to release energy to...

All female mammals have a clitoris, the sole purpose of which is to react to sexual stimulation, and presumably this stimulation has evolved to be pleasurable for most species. But establishing...

To create a sound, we have to set matter - whether it's a gas like air, a liquid or even a solid material - in regular motion, creating a wave of specific frequencies, which we hear as a sound of...

Mirrors don’t reverse left and right either – that’s just our interpretation of what happens. Your reflection in the mirror is actually reversed front to back – if you have...

Discovered by an American student named Gary Flandro in the mid-1960s, the slingshot manoeuvre usually involves spacecraft briefly 'coat-tailing' a planet orbiting the Sun, extracting some of the...

The ice disappears because the wind blows away water molecules that have evaporated or 'sublimed' from the ice, so the ice slowly shrinks in size. The molecules that escape are those with the...