help on best antenna to use in mountain area?
Hi ka4dsk Frank here. we will be relocating from the flat lands of FL. where i have been using beams and a 80 meter loop at 55feet all have been great now i will be on a high mountain that is about 3000 ft in height and i will be at the 2000 foot level and clear to the south,west and north only,with a very steep drop ,like 45 degrees.Also a lot of large trees all around .
no way to put up my loop. would a vertal be best ? location will be near CLAYTON gA.THANKS FOR ANY HELP TO A FLAT LANDER Frank
going from sea level to 2000 ft
does not change things that much
80 meter full wave loop at 55 ft
at sea level and 2000 ft
is the more or less the same thing
above sea level / higher elevation
only really comes in to play
when running VHF UHF or microwave
then it makes a big difference
ahhh but Frank there is a way to use your loop...make it verticle,in the form of a triangle(delta)mine works pretty good..easier to keep up than most..73 Rick
You will find a huge difference in the favored direction for horizontal polarization as the far field reinfocement will take place many wavelengths away horizontally and that point will be your apparent height above the ground below. The primary lobe radiation angle will be extremely low but filled with multiple other lobes that can fill in but there will be just as many nulls somewhat mitigated by actual ground conductivity. You may also get some signal reflection enhancement (gain) from behind depending of the metallic content. This could be a kickass DX location to SA, Pacific and many parts of Asia. You will have to work Europe and Africa long path
Only the higher lobes will get over the higher elevations, maybe enough for cloud warmer contacts....it depends on the up slope angle.
A vertical may be completely useless as the immediate area ground conductivity establishes the angle (lower portion) and strength of the major lobe. I seriously doubt it would ever equal a horizontal from your quick description.
Consider running open wire feeders to an antenna on top of the mountain
thanks for quick reply.i feel much better now on having a station that is usefull under the conditions we will be living at may be able to reach the JA ststions that don,t haappen to much from our location in FL. thanks to carl and rick
ON4UN (in his book) says sloping ground is a benefit for a vertical much the same as it is for a horizontal antenna. Experimental data seems to confirm this. Ground conductivity can be a significant factor however. Ground quality is usually poor on a mountain. Unfortunately there is no software available for analysis. K6STI wrote a program that could handle verticals over arbitrary terrain but it is no longer available. I haven't seen it and don't know how good it is. You are probably correct about the horizontal antenna being better, but that is because of the ground gain you get with the horizontal antenna. However for DX on 160 meters it is likely that a vertical will beat the horizontal antenna no matter the terrain.
Originally Posted by KM1H
Actually from KA4DSK's description it's impossible to guess if there will be any benefit from his location or not. He said he was on a 3000 ft mountain at the 2000 ft level. Usually when you are in a mountainous area, there is another mountain close by. Depending on what's there he could be blocked in other directions as well. Guessing the answer is a big crap shoot without more information. Although in the up-hill direction, you don't have to go too far out on a limb to say that DX conditions will be poor. RF doesn't penetrate mountains very easily.
I wouldnt expect a mountain with a 45 degree slope to maintain much soil cover and what there is wont be all that good. Throwing a hundred radials down the slope might help but there is also the slight problem of installing an efficient radiator to start with.
Im on top of a hill but with pretty useless ground only 1-3' down until I hit solid rock. Ive measured RF ground conductivity on Beverages to be around 200 Ohms where it actually helps performance by tilting the wave more and shorter lengths work well.
For transmitting, elevated radials are ideal here as witnessed by my country counts and past contest multiplier/QSO results.
thanks carl lots of rock at ground level here in GA. will try elevated radials and vert antenna first as that would be easy to play with before getting back to what i,m useing here in FL.an 80 meter loop at 50 feet on six supports that works great Frank