CoCo Antenna - 2, 4, 6, 8 & 12 Elements - Simulation Results

ab cd

ab cd

Senior Member
Simulation results show that CoCo is a High Gain, High Impedance/High SWR Antenna.
Due to its high SWR, an impedance matching device is required to be incorporated in the feed coax (i.e. between CoCo and Receiver) to bring down SWR to 1.5 or less, in order to fully utilize the high gain of CoCo.

2, 4, 6, 8, 12 Element CoCo SWR GAIN.png



2-ELEMENTS
2-element simulation.png



4-ELEMENTS
4-element simulation.png




6-ELEMENTS
6-element simulation.png




8-ELEMENTS
8-element simulation.png




12-ELEMENTS
12-element simulation.png



.
 
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The above simulations are for CoCo alone, and do not include affect of feed coax.

Adding feed coax will change performance of CoCo, unless some feed isolation arrangement such as decoupling sleeve (also known as sleeve balun) is provided. After adding decoupling sleeve at the feed point, the affect of feed coax becomes small, and the antenna performs almost as the stimulation shows.

The addition of isolating arrangement however does NOT improve SWR or reduce impedance. An impedance matching arrangement will still be required to get good SWR (1.5 or less) and a good performance.

Above simulations were for for antenna in free space.
Now I have modified the simulation model (4-element and 8-element coco) for antenna at 7 meters (23 feet) above real ground.

This has affected the radiation pattern and the gain, but the SWR/Impedance did not change. It remained high at same values as those for antenna in free space, and still require impedance matching arrangement to bring down SWR to a decent value (1.5 and less).


4-ELEMENT, 7 meters (23 feet) above ground
4-element simulation-7 m above ground.png




8-ELEMENT, 7 meters (23 feet) above ground
8-element simulation-7 m above ground.png
 
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