quater wavelength

hi everybody,
can any body tell me why we required legth of antenna minimum of quater wavelength for faithfull reception.If we not transmit ,does it effect the regeneration of wave at the receiving side..
what is te mathematical relation between wavelength and antenna length.

thanks
saurabh

this is because the wave amplifies itself in those lengths,.. resonance right?...
half or a quarter if I'm not mistaken...

http://www.newton.dep.anl.gov/askasc...9/eng99258.htm

http://en.wikipedia.org/wiki/Antenna_(electronics)


A couple of good links. The mirror and ruler paragraph at the bottom of the first explains why a 1/4 and ground is like a 1/2 length antenna.

Hi
To my understanding, quarter wavelength long antenna is for monopole type(when grounded, it works like dipole). If we use dipole type antenna, it is half-wavelength long. The reason is efficiency of antenna depends on how long it is relative to operating wavelength. Usually antenna with 1/2 wavelength length has maximum achieable efficiency.

Hi,
a receiving antenna does not have to be quarter wave. Even a transmitting antenna does not have to. It is just an simple type of antenna. The input impedance is low (about 35...60Ohms, depends on ground and environment) so you don't need an additional matching circuit in a 50 Ohm system.

Ciao