[TowerTalk] Greyline Performance antennas

[Jim Brown]

On 10/17/2020 9:38 AM, Kim Elmore wrote:
> I have a F12 Sigma 80 antenna, which is an OCF vertical dipole with 
> inductive loading at the feed point and a hairpin match. While it 
> *requires* a common-mode choke at the feed point, it works very well for 
> DX. On stateside contacts, I think its radiation angle is too low and 
> performance for anything within about 400 mi is much worse than for my 
> inverted V with (apex at 40 ft). On DX, though, it does MUCH better than 
> the inverted V.

Verticals shorter than about 3/4 wavelength, by their nature, have a low 
radiation angle. It has nothing to do with the design of the F12 antenna 
other than it's height. This is made clear by a study of the link I 
posted for my study of vertical antennas and horizontal antennas, and by 
study of the ARRL Antenna Book, the ON4UN book, and the Antennas chapter 
of the ARRL Handbook.

  I have no radials beneath this antenna.

By it's design, no radials are needed.

> I know a friend is buying a Greyline antenna for his QTH. They initially 
> look a bit pricey, but I've not actually seen one, so I don't what the 
> build quality is truly like. Assuming it's build quality is pretty good, 
> and assuming it has a good CM choke, 

 From what I see on their website, that may not be a good assumption.

there's no reason why it shouldn't
> perform relatively well given the constraints. Certainly better than no 
> antenna at all!

This last sentence is the key -- if you're stuck in an HOA, it's better 
than nothing.

73, Jim K9YC