Reduced-size K9AY
Are 7.5m high and a 10m free-circle around the antenna still too big for your city lot ?
No problem, just shrink all dimensions proportionnally and that's almost it !
Full size : 7.5m high, 10m circle
1/2 size : 3.75m high, 5m circle
1/4 size : 2m high, 2.5m circle
Reducing the capture size of the original K9AY will NOT impact his directional pattern.
But,
- Special care should be brought on common mode noise
- Termination resistor value may be slightly different versus bigger size (so a remote control of resistor value is recommended)
- Gain will decrease as per the size, and the use of an external pre-filtered preamplifier becomes mandatory, above all on Top band.
- Reducing even more the size (1/4 size and smaller) is very unlikely to be effective, above all on 160m.
No problem, just shrink all dimensions proportionnally and that's almost it !
Full size : 7.5m high, 10m circle
1/2 size : 3.75m high, 5m circle
1/4 size : 2m high, 2.5m circle
Reducing the capture size of the original K9AY will NOT impact his directional pattern.
But,
- Special care should be brought on common mode noise
- Termination resistor value may be slightly different versus bigger size (so a remote control of resistor value is recommended)
- Gain will decrease as per the size, and the use of an external pre-filtered preamplifier becomes mandatory, above all on Top band.
- Reducing even more the size (1/4 size and smaller) is very unlikely to be effective, above all on 160m.
160m
Full size : -23dBi 1/2 size : -33dBi 1/4 size : -44dBi |
80m
Full size : -13dBi 1/2 size : -22dBi 1/4 size : -34dBi |
40m
Full size : -4dBi 1/2 size : -12dBi 1/4 size : -23dBi |