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+--- Thread: Maldol HVU-8 Radiation Pattern (/thread-634.html)
Maldol HVU-8 Radiation Pattern - VK2CSW - 15-09-2018
Hi All,
Does anyone happen to have a diagram that shows the radiation pattern of one of these antennas?
In my foray into FT-8 I seem to have a pattern of NE to SW contacts. I have spun it 90° and I'll see what I see.
Cheers
Or more correctly, I shall hear what I hear...
RE: Maldol HVU-8 Radiation Pattern - VK4ADC - 15-09-2018
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/uploads/2013/09/HVU-8_Inst.pdf refers
RE: Maldol HVU-8 Radiation Pattern - VK2CSW - 18-09-2018
The band I've noticed it most on is 20m.
I have it constructed pretty much as per the Maldol diagram, (Except it has no 80m radiator as it did not survive storage) which means on 20 radiator and radial roughly oppose each other. I imagine the lobes would be out to the sides of this configuration.
I have rotated the whole assembly 90° and first indications are that it is very quiet now.
I will persist with this, as time permits, as I've only been running like this for an hour or so mid-afternoon.