Re: Sorry for the late reply.
pike said:
Nigel Goodwin said:
Generally the higher the frequency, the shorter the range. Anything VHF or UHF is basically 'line of site', but licence free is usually 100m or so.
How can higher frequency mean shorter range??? Ive never heard of such "phenomenon" before.
You're obviously not a radio amateur :lol:
If you want to communicate round the world you use lower frequencies, these are reflected from layers in the upper atmosphere and 'bounce' round the world. This is why you can't use low frequencies to communicate with satellites or space craft.
Once you get to about 30MHz this bouncing becomes less effective, and you can broadcast into space above these frequencies. By VHF frequencies there's no 'bounce' at all and the radio waves travel on into space.
Meanwhile, back on earth, things work in a 'similar' sort of way.
Radio waves, like light waves, travel in straight lines - BUT they do seem to 'droop' to some extend. If you're either side of a hill you don't have 'line of sight', so a radio shouldn't work - but, depending on the frequency used, it will work over the hill to some extent. VHF will 'bend' so far down, but by UHF frequencies it won't work at all.
Also, higher frequencies are absorbed more by water in the atmosphere, so this again reduces range at higher frequencies.
As a radio amateur it becomes very obvious that you can get much further at 2M (VHF) than you can at 70CM (UHF), from the same place, with the same power.
If you want more information about progagation at radio frequencies, try amateur radio text books.