[TowerTalk] 80M Delta Loop

[kq2m at kq2m.com]

Jim,

I mentioned "one antenna that does work well even over poor ground", not 
the best antenna overall.  And it does work very well - enough to let me 
work 39 zones and 300+ countries on 80 not to mention being a very 
effective antenna in DX contests when the K index is below 5.

I elevated the radials specifically to reduce the impact of lossy 
"earth" that my 4-square would otherwise suffer and due to the fact that 
there is very little actual "ground" where I have my 4-square - it 
resides above ledge, jagged uneven ledge, and a few inches of "dirt" so 
devoid of nutrients that it can't grow anything but weeds, thorn bushes 
and poison ivy.  That's what hilltops are like in Western Central CT.  
Great for beverages but not so much for vertically polarized antennas.

Sure, a 4-square of full-size aluminum verticals with 32 radials per leg 
would be an improvement but that is not an option at my qth.  So it was 
either a 4-square or an Inv L or Inv V at a low height, both of which 
were far worse.  You have to do the best that you can with what you have 
and the 4-square works best here.

73

Bob, KQ2M



On 2024-07-24 14:41, Jim Brown wrote:
> On 7/24/2024 11:31 AM, kq2m at kq2m.com wrote:
>> One antenna that does work well even over poor ground is a 4-square 
>> with elevated radials, preferably above .05 wavelength in height.
> 
> Poor soil degrades the efficiency of vertically polarized antennas both 
> under the antenna AND in the far field, where the ground reflection 
> that reinforces the direct wave is created. Radial systems affect ONLY 
> what happens under the radials -- they screen the direct field of the 
> antenna from the lossy earth, and give the antenna a low resistance 
> path for its return current. That's ALL that they do. They cannot 
> compensate for lossy ground in the far field.
> 
> But ground characteristics DO vary with location, even with lousy 
> ground under the antenna, good ground in the far field can support the 
> needed reflection, making the antenna work well. That's the classic 
> case of a vertical near salt water. And N6BT, well-known for his "Team 
> Vertical" setups, has recently done field measurements with a drone to 
> show that a vertical very close to a drop-off (his testing was on a 
> mesa in AZ) produces a very strong signal in the direction of the 
> dropoff. He first showed this work as part of the Pacificon Antenna 
> Forum about five years ago, to which we both often contributed.
> 
> 73, Jim K9YC
> 
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