Hi guys,

I've been reading up on the different types of radio waves etc and am
getting really confused between the concept different wavelength waves
travelling different distances before being attenuated etc.

The more I think about it all the more confused I am becomming and I
was wondering if someone would be able to help me with this....

Basically I have been told that shorter wavelength waves attenuate and
scatter more easily. So working on this principle I know that medium
waves (MW eg AM radio) are longer in wavelength than VHF (ie FM radio),
so why is it that in car parks etc (i.e. under a roof) you can still
pick up FM on the radio but not MW. Surely FM being shorter in
wavelength (and consequently higher freq) will be scattered more? Is
this to do with diffraction instead? Longer waves diffract more
readily, so as FM is longer it diffracts more and is therefore heard
'around corners' (sorry for putting it like that!), whereas MW would
not be?

So, shortwave is also longer in wavelength than FM so perhaps this is
better for transmitting over long distances ie for international
transmission, but MW is even longer in wavelength so why is this not
used instead?

Lastly, SHF and EHF are used for satellite transmissions, but these are
very small wavelengths for radio waves so surely here the scattering
and attenuation would be so large that this would impede its path from
the satellite to the ground? Or again are we just using SHF and EHF as
diffraction effects would be minimal?

If anyone could shed any light on this topic for me it would be really
appreciated.

Cheers

DC