# Antenna

Discussion in 'Wireless & RF Design' started by suraj kamble, Jul 5, 2012.

1. ### suraj kamble Thread Starter New Member

Jul 5, 2012
1
0
Hello there..I'm new to electronics, just wanted to know what's the maximum voltage that an antenna can transfer? And why do we consider the speed of light for the calculation of wavelength of a wave even though when it is in the conductor(I mean the speed of the electrons must be considered in λ=v/f instead of speed of the photons).

2. ### MrChips Moderator

Oct 2, 2009
12,623
3,451
The varying voltage across the antenna produces an electromagnetic wave that propagates at the speed of light.

There is no maximum voltage. You are limited by the transmitter output and the insulation properties of feed cables, insulators, support and guy wires holding up the antenna.

3. ### K7GUH Member

Jan 28, 2011
191
23
One considers the speed of light for signals in free space. If the signal is to be fed into a wire antenna, one must take into account the velocity factor of that wire, which affects the frequency at which the antenna is resonant. For wire antennas in general, the velocity factor is assumed to be 0.95 of the free space value. For real antennas (as distinguished from theoretical ones), one must take into account any other factors which may apply, such as height above earth ground.

4. ### Papabravo Expert

Feb 24, 2006
10,338
1,850
An antenna analyzer is often used to measure the antenna at the feedpoint, or the complete system of antenna and feedline from the transmitter's point of view. In this way you can determine the resonant frequency of the antenna as well as the "bandwidth" of the antenna, defined as the frequency range over which the return loss is less than some value e.g. "less than -22 dB".