Contents
What is the difference between radio and antenna?
In transmission, a radio transmitter supplies an electric current to the antenna’s terminals, and the antenna radiates the energy from the current as electromagnetic waves (radio waves). An antenna is an array of conductors (elements), electrically connected to the receiver or transmitter.
How do crystals work in radios?
The crystal functions as an envelope detector, rectifying the alternating current radio signal to a pulsing direct current, the peaks of which trace out the audio signal, so it can be converted to sound by the earphone, which is connected to the detector.
Why is it important to understand antenna theory?
In depth antenna theory can become quite complicated, but a qualitative and simplified theoretical explanation help help in understanding what is actually happening, how the radio antennas work, and how they can be optimised. This can be key when setting up a radio communications system or link.
What kind of antenna do you need for a crystal radio?
The simplest antenna for a crystal radio is a long wire (say 10m), and up as high as you can get it. On the roof is best if you can get up there. The wire should be stretched out, not rolled up.
What makes an antenna transmit and receive the same way?
One of the key aspects about any radio antenna is whether it will receive and transmit in the same way. Any passive antenna, i.e. one that does not use an embedded electronic circuit such as an active antenna will work in the same way transmitting and receiving.
What makes a passive antenna the same as an active antenna?
Any passive antenna, i.e. one that does not use an embedded electronic circuit such as an active antenna will work in the same way transmitting and receiving. It will have the same gain, the same directional pattern, polarisation, the same impedance and other aspects for both transmitting and receiving.