15-09-2018, 05:26 PM
Colin
Which particular bands are you seeing the directionality on ??
(and did you assemble it exactly as per the instructions ? )
I have downloaded the PDF and I can't really be surprised if there is a non-omidirectional polar response due to the physical radial radiator and counterpoise arrangements.. There wouldn't be a pattern provided because every installation will be different (height, nearby objects) and it would be different band-by-band anyway.
If you remember that maximum radiation will be a composite of the radiation that occurs perpendicular to each of those tuned elements and radial arm components individually, the only band that it might not apply to is 3.5MHz - because for that band the radiator piece is vertical - but the ground radial is a protruding horizontal so it will probably be shaped on that band too. All other HF bands have
variously-shaped angles between the two types of tuned arms so the polar pattern will undoubtedly be irregular.
The only way to get a true omnidirectional pattern is a single radiator for a single band over a true totally-circular counterpoise of the correct dimensions - and, one radial arm per band does not constitute a true counterpoise. (oh, and mounted in free space....)
Doug
http://www.cometantenna.com/wp-content/u...8_Inst.pdf refers
Which particular bands are you seeing the directionality on ??
(and did you assemble it exactly as per the instructions ? )
I have downloaded the PDF and I can't really be surprised if there is a non-omidirectional polar response due to the physical radial radiator and counterpoise arrangements.. There wouldn't be a pattern provided because every installation will be different (height, nearby objects) and it would be different band-by-band anyway.
If you remember that maximum radiation will be a composite of the radiation that occurs perpendicular to each of those tuned elements and radial arm components individually, the only band that it might not apply to is 3.5MHz - because for that band the radiator piece is vertical - but the ground radial is a protruding horizontal so it will probably be shaped on that band too. All other HF bands have
variously-shaped angles between the two types of tuned arms so the polar pattern will undoubtedly be irregular.
The only way to get a true omnidirectional pattern is a single radiator for a single band over a true totally-circular counterpoise of the correct dimensions - and, one radial arm per band does not constitute a true counterpoise. (oh, and mounted in free space....)
Doug
http://www.cometantenna.com/wp-content/u...8_Inst.pdf refers
Doug VK4ADC @ QG62LG51
http://www.vk4adc.com
This Forum is only going to be as interesting as the posts it contains.
If you have a comment or question, post it as it may trigger or answer the query in someone else's mind.
http://www.vk4adc.com
This Forum is only going to be as interesting as the posts it contains.
If you have a comment or question, post it as it may trigger or answer the query in someone else's mind.