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I selected the Comtek product because of its availability, cost, and performance. Other manufacturers make other couplers, or one could design a coupler from scratch. The Hybrid Quadrature Phasing Coupler produces 4 feeds for the antennas, one is 90 degrees lead phase, two are in phase, and the last is 90 degrees out of phase. To produce a beam in the NE direction, the NE element is fed in a lead phase, the SW element is fed in a lag phase, and the NW and SE elements are fed in phase. The Hybrid Quadrature Phasing Coupler also balances the power feed to each antenna. Another feature of the Hybrid Quadrature Phasing Coupler is that all unbalanced power in antennas is routed to 50 ohm termination (dummy load). In my station, I routed this dump power through enough RG-58 coax to reach the ham shack, and I use a power wattmeter to measure dump power into a dummy load. Any antenna failure will manifest itself as excessive power dumping into the load. |
| The Comtek Box is mounted in the center of the array. I premarked the side with indicators for the antenna ports, the feed port, and the load port. The 3 wire control cable is installed through the rubber grommet. All cable to the verticals is phase matched at 3650 KHz, and made with RG-6 coax (that has a copper braid). The feed to the Comtek box is RG-213 coax suitable for underground burial, and the line which feeds the inbalance power is RG-58 (also suitable for underground feed). All radial rings (at the verticals) are grounded with an 8 foot 5/8 inch ground rod, and the 4 ground rods are connected together using 6 AWG solid ground wire. This point marks the center, and another ground rod is set, connecting the 6 AWG wires together, and also grounding the Comtek box. When installation is completed, the Comtek Box is covered with a plastic bucket, and the bucket is "sealed" to prevent wasp and hornets from maqking a home there. |
