Originally Posted by gireesh
Thanks for the references. Has anyone done simulations on the crescent/pie above with the dimensions you provided
I'm sure that John Edwin Ross, III, Moab, UT, who invented the tapered UHF loop for Antennas Direct did some computer simulations. See patent application
US 2013/0162487 A1
You can look at the development of his design here:
I have question on the directors and reflector. Typically, they are connected to the the antenna element by the virtue of the fact that all elements are mounted on a metal spine. Because of that I assumed that these are just steel rods for transverse stability of the polycarbonate planes. I do know from my research every piece of metal can impact the currents in the antenna. So, of course there would be an effect. I have attached pictures with measurements.
What you had in the antenna when you purchased it is the classic Yagi antenna, more properly called the Yagi-Uda antenna because
It was invented in 1926 by Shintaro Uda of Tohoku Imperial University, Japan, and (with a lesser role played by his colleague) Hidetsugu Yagi.
The reflector and directors are usually supported at the center (the "spine" is called a "boom") because the ends are high impedance points that are sensitive to losses. They are supported at the ends in your antenna for convenience.
The directors and reflector are "parasitic elements" that are not connected to anything. They pick up the signal energy from the transmitter which creates a current in the parasitic element. Since energy can not be created or destroyed, only transformed, the energy is radiated by the parasitic element and is picked up by the driven element and is added to the energy already being induced in it by the signal. This is how the parasitic elements increase the gain of the antenna. The driven element that is connected to your feedine is so named because the computer model energizes the antenna at the feedpoint as if it were a transmitting antenna. The characteristics of transmitting and receiving are identical, as defined by the Antenna Reciprocity Theorem.
Wondering how I can run a simulation on this, and hopefully try to improve its performance.
You can learn to do computer modeling with free software. Forum member holl_ands is also on the DHC forum (digitalhome.ca) and might be willing to guide you:
and in particular
I don't do computer modeling. I have been doing antenna experiments since I was 8 years old; I'm now 85, and still learning. I would rather spend the years I have left making antenna and signal measurements for real-world proof of performance, than climbing the computer modeling learning curve for antennas.
If you give some accurate measurements to holl_ands, he might be willing to model your antenna.
If you hope to make improvements in your antenna, you must have a way to make accurate comparisons of before and after. OTA signals are constantly changing in strength, so if you don't have a steady signal source, you must make a rapid switch between two antennas for a valid comparison.