horizontal vs sloped ground elements on a vertical ?

[Marconi]

Hey DB, what is the radiator length in inches for your 1/4 wave model, post #5, at the top of this thread?

 

[The DB]

DB
i think we have established in other threads that when mounted at the same tip height there is little difference in gain between simple verticals with no or low loss matching setups,
the main advantage one design has over another is height of current maxima above ground,

Agreed

a 5/8 advantage over 1/2waves is the height, even though 5/8 has 1/8wave of out of phase currents the extra height of current maxima above ground still holds an advantage UNTIL you raise the 1/2wave to the same tip height where the 1/2wave has a little more gain at low angles,

Agreed

its not the magnitude of gain difference in your model that has me confused,
its the trend towards lower gain with steeper radials im having trouble with,

OK

is the result the same in free space or higher above ground,

That is a good question, I will have to try those later.

seems odd that all we ever needed was a ratshack 1/4wave ground-plane at the same tip height as other peoples much larger & more expensive antennas,

or an astroplane.

This doesn't seem odd to me. Once the realization comes that it isn't the length of the antenna but the height of the current node that is key.

Hey DB, what is the radiator length in inches for your 1/4 wave model, post #5, at the top of this thread?

0 degrees, 97.58 inches
15 degrees, 95.58 inches
30 degrees, 93.75 inches
45 degrees, 92.04 inches
60 degrees, 90.435 inches

In all cases, the vertical elements are the exact same length as the radials. In all cases, the antenna was tuned to have close to no reactance. In all cases, there is a single segment feed point, a segment whose diameter was modified to bring AGT to 1. In all cases I used four radials.


The DB

 

[Marconi]

Thanks DB, the info is helpful.

 

[Marconi]

DB, I didn't fully understand your idea back when the subject might have come up in conversations. Correct or not, at some point I recall thinking that you were just using very thin wire diameters to help mitigate any segment errors as your wire angles got closer together like they can in some models like the Sigma4 and the Starduster.

Quite by accident, I have done about the same thing in error once while I was making diameter adjustments to the radiator wire for my 1/4 wave model. I saw about the same results...but without adding an extra 1 segment wire. At the time I did not think this was a scheme however...I just thought I messed up and it fixed the model by chance.

I still didn't fully understand what was going on until yesterday when reading your comments. I just had a vague recollection of something strange happening to a model at some point in the past.

Yesterday, after I applied your scheme I had the thought...how did the results compare to the way I try and get a good AVG result for my models. I typically will fiddle with the segment count in a Free Space model. I watch the AVG results and make very small adjustments. This sometimes means I'm changing segment count with several wires and then it can be very tedious. Using your 1 segment wire idea is a much simpler and straight forward approach.

I have an antenna I make using 5 x 102" ss whips called the Marconi 5x. It is pretty much similar to your 1/4 wave model. I use my scheme on this one to get the AVG results to 1.00, and I don't have to adjust the wire diameter...I just make small changes to the segment count for the source wire (radiator) and it does about the same thing...while leaving the antenna dimensions as specified.

My idea came from a conservation with Roy Leawallen...when I asked him if there was a preferred scheme for setting the segments. He said NO!, but he cautioned me to try and make very small incremental adjustments to the segment count for the source wire in a Free Space model...and to always watch the AVG results carefully.

Again, thanks for the information.