Topband: Base Insulators for Verticals

[Tim Duffy K3LR]

Hello Mark!

This 160 meter vertical Yagi array is well documented in the ON4UN Low Band book
(last two editions).

I think 6 parasitics may not be justified. The half power beam width is large
enough off the front of this 3 element vertical Yagi (equivalent)
that the gain nulls at the adjacent pattern cross points are small. I've never
found the gain null to be a problem when working DX with this array.
The pattern is very tight on the back lobe as well (F/B is at least 30 dB at the
optimized frequency point which is 1830 KHz in my array).
6 parasitics would require two additional ground fields. It is bad enough
installing 5!

AA1K does have an additional director in his 45 degree array making it 4
elements in that direction.
I think that is a great idea and the NEC model also indicates increased gain
(narrows the beam width of the forward lobe).

AA1K, VE3EJ and others have built this antenna. It is a tremendous performer for
Top Band!

73!
Tim K3LR

There are pictures of this antenna at http://www.k3lr.com


Mark Beckwith wrote:

> >It seems like the K3LR array could be built with 6 parasitics, and
> switchable in 6 directions (i.e. hexagonal instead of square).  Do you have
> a gut feeling on this?
>