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.
(strictly according to Maarten Baer design requirements, learn more, please click: http://www.maartenbaert.be/quadcopters/antennas/triple-feed-patch-antenna/)
PRODUCT BASIC INFORMATION
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.
|Simulation model. The two plates are wave ports that act as stand-ins for the SMA connectors.||3D radiation pattern. Look at the 2D version if you actually want to see the numbers.||Vertical cross-section taken at various angles.|
|VNA measurements (S-parameters). S11 and S22 indicate the reflected power at port 1 and 2 respectively. S12 and S21 indicate how much power is leaking from one port to the other.|