[TowerTalk] K9YC vertical dipole test....
jim at audiosystemsgroup.com
Fri Nov 15 08:02:12 EST 2013
On 11/15/2013 4:19 AM, Peter FORBES wrote:
> My question related to just how effective measuring vertically polarised
> signals at approximately zero elevation angle is with regard to DXing on
> 80mx and 40mx.
> Given the choice, most would opt for an elevated vertical. However on 80mx
> and to a lesser extent on 40mx a ground mounted antenna on good ground can
> be an effective DX antenna.
All of which is why I published the full vertical elevation plots for
each modeled condition. :)
Note also that, taking wavelength into account, it's rather impractical
for most of us to elevate a vertical antenna for 80 or 160 enough to
develop nulls in the vertical pattern. The benefits of elevating radials
for the lower bands is well known, so I'd make an educated guess that
elevating antennas for 80 and 160 would produce good results if it could
be done. Thanks to my trees, I could probably get an 80M vertical
quarter wave and radials up in the air enough to improve performance
over a ground-mounted vertical. But I've got horizontal dipoles for 80
and 40M up 110-120 ft at right angles, and they play awfully well. And I
just added a reflector to one of them to help with EU.
As to measurements -- Dan correctly observes that our terrain is quite
irregular, nowhere close to flat. But we were able to make these
measurements ONLY because we had convenient supports from which we could
hoist the test dipole -- a support rope strung between redwoods that
also holds W6GJB's 80M dipole. And that support rope wasn't free -- Glen
paid tree climbers to put the pulleys there, those guys cost > $600/day,
and it took two days of work. I don't know anyone with the financial
resources to make the helicopter measurements you've suggested. We're
just a couple of retired old farts living on our savings.
73, Jim K9YC
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