Plasma, your antenna is printed in the x-z plane and has omni directional in the x-y plane.
Savedadogs, thanks for referring me to a paper. I'm working on getting it, though it's difficult because it was presented at a conference in China, just like you said.
A. Lai, KMKH Leong, and T. Itoh
Dual-mode compact microstrip antenna based on fundamental backward wave
Asia Pacific Microwave Conference
You are also correct in that I'm looking for an omni-directional antenna.
I'm going to simulate an antenna based in the circular structure you described previously.
The results are below. The first plot is an x-y slice at theta = 90 degrees (E phi plane). I used a pcb thickness of 1.6mm. The radiation pattern isn't really what I'm looking for. Maybe I don't understand your description of the fixed antenna. I know that if you use an antenna that is fixed off the pcb by 7 to 10 mm then you can get an omni directional pattern, but that isn't a simple pcb printed antenna. Is that what you are talking about?