[VHFcontesting] A question of altitude

[MICHAEL SAPP]

Hi Steve & Folks:  IMHO there are times when a smaller antenna raised higher is more effective than a lower high-gain antenna when terrian obstructions are present out a few hundred wavelengths.  For example, my home qth is at 1165 ASL and to the SE of me some 700~800 ft away is a main road where the curb is at 1200 ASL.  I have a 10 db 2M yagi on the chimney around 28ft above ground and a pair of stacked 2M loops at 40 and 44ft.  The loops beat the yagi hands down in that direction as they are clearing the road curb some 700~800 ft away by 10feet of elevation whereas the yagi on the chimney is essentially pointed right at curb level.  Another observation is that even though the loop antennas are not entirely clear of the nearby tree tops, they performed notably better perched on 20 feet of mast around that 40-44ft level than they did when they were just 10 feet lower. I attribute that to a local ground clutter situation with plenty of nearby tree absorbers. Being near the tree tops is much better than half way up tree level if you cannot clear them.  Of course being mobile you can manuever around ground obsticals so the 13ft6" Interstate highway limit may not be that much of a hinderence compared to a fixed station. It may be worth moving the rover a few hundred feet or more even if the ASL difference is 5 or 10 feet for a given direction. Generally speaking highway curbs make lousy rado wave reflectors.  Mike wa3tts