The Triple Feed Patch antenna is a directional circularly polarized antenna that I created in collaboration with Robin Theunis, one of my co-workers. The main design goals were:
Good radiation efficiency. Most FR4-based patches have terrible efficiency because FR4 is very lossy at 5.8 GHz.
Good axial ratio, not just directly perpendicular to the patch but also off-center.
Cheap and easy to manufacture with high accuracy, even for a hobbyist.
Center frequency: 5.8 GHz
Bandwidth: 660 MHz (5.47 – 6.13 GHz)
Matching: S11 < -20 dB, VSWR < 1.22 (at center frequency)
Axial ratio: < 1.3
Antenna gain: 9.4 dBi
Half power beam width: 55° (horizontal and vertical)
Radiation efficiency: 83.5%
These values are based on simulation, actual measurements are below (they are very similar). The center frequency may shift a bit between batches as a result of variations in the dielectric constant of FR4. Also, not all brands of FR4 have the same dielectric constant. Frequency shifts up to 100 MHz are normal.
1 x Antenna
1 x semi rigid SMA extension
1 x Dummy Load SMA