Why are antennas needed?

Question

Why antennas are needed for radio,television,and cell phon transmission and reception?

Answer 1

the radio signal needs to be sent out from an antenna, and to be received on an antenna.  The antenna is both the "mouth" and the "ears" for the electronic radio device (phone, tv, etc).

For lower frequencies, you need a larger antenna.  For higher frequencies, you need a smaller antenna.

The signals are sent out as radio waves, electrical vibrations in the air, and when they hit an antenna of about the right lenght, they "electrically vibrate" the antenna, and the signal can be picked up by the device.

Answer 2

if u don't use an antenna in transmission it will not go very far.

the antenna is used in transmission to send the signal out.

why do you think cell phone have a tower to send the signal the farthest possible.