Put your ear to the funnel. You'll hear the sounds of the city. It's as if the street is at arm's length! All thanks to the parabolic antenna.
Article by N+1
3 min to read · May 24 2023
Put your ear to the funnel and you will hear the sounds of the city. It's as if the street is at arm's length! That's how a parabolic antenna works. Now try to catch its focus. Ask a friend to walk in front of the antenna. At this time — any sentence or sing your favorite song. The place where your friend can hear you loudest will be the focus of the antenna.
How an antenna amplifies sound
We hear sound because the organs in our ears sense air vibrations - sound waves. They reflect well off hard surfaces, so we can hear echoes.
Sound waves are created by molecules vibrating at a certain frequency. If the molecules "shake" too slowly for our ears, we will not hear anything. Such waves are called infrasound and can be recognized, for example, by whales. If the molecules vibrate too fast, we won't feel anything either. These waves are ultrasound. Dogs can hear it very well. They even use special ultrasonic whistles to train them. Humans can't hear these signals, but dogs respond well to this whistle.
Why we can hear sounds so clearly from a long distance, when we put our ear to the funnel?
This is the workings of a parabolic antenna. It looks a bit like a dish.
A remarkable property of the parabola shape is that all waves traveling in its direction at one angle are reflected and collected at one point. This point is called the focus. Sound is focused at this point. It is at this point that we have placed the funnel so that the sound will enter the tube and reach you.
Parabolic antennas are used as high gain antennas for many different types of communications: data communications, satellite communications, and even spacecraft communications.