In a thread on Marconi's I-10k model I was asked about my modeling of a fully functional gamma match. I decided to create a new thread as this is a model of a different antenna. Enjoy the video.
The DB
The DB
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Base Gamma match on Vector antenna models
- Thread starter The DB
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All very good.
But how is this program distinguishing between 'efficiency' and 'radiated efficiency'?
But how is this program distinguishing between 'efficiency' and 'radiated efficiency'?
When calculating efficiency, the software takes the power supplied by the source, in this case 100 watts, and compares it to the power radiated. You can actually see the power radiated in the video above by looking in the 4nec2 window for the "Radiat-power" information. This is different than the power being supplied by the source because of things like non-perfect conductors (I used aluminum), loads like inductors and capacitors (their is a capacitor in this model) and other items that 4nec2 lets me add to the model, like logical matching networks (L networks, pi networks, matching stubs, ect)
When calculating radiation efficiency (Radiat-eff.) line, the system takes all of the radiated power radiated in every individual direction, then averages this. This average will get you a number between 0 and 1. If the number is, say, 0.7037, then you have an efficiency of 70.37%.
Two very different methods to calculate efficiency, and these are done to show efficiency at two different points in the antenna system.
The DB
Very good video Steve. Your model used a gamma that is similar to my Sigma4 model I did while back. I was also working on an idea that somebody was suggesting adding horizontal radials to the bottom of the antenna. I ended up with 3 x 0.50" x 89" inch radials showing maximum gain. Just by coincidence I used a S4 model that I was trying to make the gamma work...instead of just hanging there is free space...doing nothing.
I don't have it fine tuned yet but the match is fair and the AGT = 0.958. It needs a little fine tuning to the placement and value of the (1) capacitor I added to the gamma match, and the 3 wires are all attached to the antenna now. It just so happened to end up close to 50 ohms at 28" above the radial hub at the base. It is similarly placed to my AS version of the S4 suggesting the tap point at 28" inches up the radiator.
Thanks for helping me learn something new today...learning something new is always a blessing.
Are you going to post this model so we can compare performance?
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Steve, I got my Sigma4 and my NV4K working with a gamma.
But, I'm curious what you did with your gamma with several insertion devices on the gamma. Can you share any details with me or give me a link to the calculator you used and I'll try and figure it out?
I've got a Big Chief tablet and a #2 lead pencil. I've just about worn-out the numbers on my trusty old slide rule. I need some help on how to broadband these gammas like you suggested.
But, I'm curious what you did with your gamma with several insertion devices on the gamma. Can you share any details with me or give me a link to the calculator you used and I'll try and figure it out?
I've got a Big Chief tablet and a #2 lead pencil. I've just about worn-out the numbers on my trusty old slide rule. I need some help on how to broadband these gammas like you suggested.
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