I am experimenting with a DDRR antenna for two meters because I need a low profile vertically polarized antenna.
I’ve seen several examples on the web but no technical data on how the dimensions are determined. Examples show a spacing above the ground plane of 2 to 4 inches. How do I calculate the optimum spacing?
Read these two reference articles. They should give you sufficient background.
PART 1: The DDRR antenna, designed by Dr. Boyer for Northrop
The DDRR (Direct driven ring radiator) was invented by Dr. Boyer from Northrop, for military applications in the 50s. It stayed classified until Dr Boyer published an article titled “Hula hoops antennas” in Electronics (Jan 11, 1963). “73 Magazine” published also a two part article from Dr. Boyer titled “Surprising Miniature low band antenna”. The article is quite technical and contains a very precise mathematical formulation of the DDRR based on transmission line theory….
PART 2: DDRR antenna - The math
In the first article, I talked about modeling the two ring DDRR and patterns. I received so many inquiries about a program to compute the dimensions that I decided to write a second section explaining the math behind the DDRR and wrote a program to do the calculations below….