On 21 abr, 17:20, suresh wrote:
hi
they say that when a radio wave hits a reflective surface and bounces
back it under goes a 180 degrees phase shift .

1,what exactly is the reason for this phase change, is it because of
the change in direction or any thing else.

2,does this phase shift of 180 degrees mean a shift in polarity(ie
from +ve to -ve and vice versa)

Hi Suresh,

Whether 180 degrees phase shift occurs, depends on the properties of
the reflector, the frequency and angle of incidence. Phase shift does
no mean change in polarization.

When you really want to know it all, search for "fresnel(l)
equations" or take a physics book on Electro Magnetics. A related
issue is "(pseudo) Brewster angle".

Keep in mind that physic books refer "angle of incidence" with respect
to the normal of the reflecting plane and radio engineers many times
use elevation angle as angle of incidence. Also when radio engineers
speak of "vertical polarized" wave reflection on earth's surface,
physicists do speak of "parallel polarization". They call "horizontal
polarization", "normal polarization".

Best regards,

Wim
PA3DJS