VHF is stopped by hills, trees, especially wet green trees, buildings & more or less anything else that is in the direct path of it. All it takes is for something to be a little higher than one of the antennas, so that it stops one from seeing the other & VHF at best deteriorates significantly, or more normally, it disappears.
VHF airband is a massive chunk of spectrum. So I normally band scan it in small chunks as radio overs tend to be short, so the quicker you can scan your chunk, the more you stand a chance of hearing.
Only scan 118.000 Mhz to 136.9750 MHz. And I personally do that in 4 chunks. Each 4MHz big & I would scan it in 8.33 khz steps, as high level comms is in 8.33khz steps, but it will also allow you to hear the more normal 25 khz steps too.
4mhz in 8.33khz steps is just under 500 steps. So you should get most overs.
Antenna wise if it's airband that interests you then commercial airband antennas are available, but the cost of the antenna is the smallest cost. You will need mounting brackets, a mast & decent coax so you keep the signal that the antenna receives. The antenna it's self need not cost more than £40, but for the coax add around £1.50 per meter, plus connectors.
A home made antenna for airband will probably perform better than a commercial one, as you can optimise it for your own needs. Budget well under £5 for a home made antenna, plus the coax.
Use something called Chocolate Block, to join the coax to a couple of lengths of wire.
The wire will need to be the the right length. But it's that simple.
The following is for 135MHz in the airband.
