The AM Forum

The KinStar antenna claims a radiating efficiency that is 98% that of a quarter wave tower with a vertical height that is 67% less than that of the quarter wave tower and with a wide bandwidth.  Full radial ground system (120 quarterwave radials).

http://www.kintronic.com/site/systems/kinstar.asp

http://www.star-h.com/publications/ieee2002.pdf

Looks interesting Don,
It would still be a problem for guys who have small lots. Many people were surprised when I told them I was using a 31 foot high vertical about 3 years ago. It was the Unihat vertical, he has a 45 foot version out now that he claims will out perform a full sized vertical for the broadcasters.
I remember a GAP antenna that was 45 feet high and that was a 'dummy load'  :P
on 160M.
You need to get on the air more often
fred

Is the Unihat vertica still  manufactured? Great site Don ;D That company has some great stuff.

Don,
      Interesting looking antenna. I'm skeptical of the manufacturers claim that it's performance is 98 percent or so equal to a regulation ground plane; and would think it's probably more in line with a folded "unipole" of the same dimensions. There's certainly nothing wrong with that.

It would be interesting to work someone who actually bought one.

Efficiency may be close to that of a 1/4 wave, but the vertical pattern will be less flattened than that of a 1/4 wave, so signal along the ground will not be quite as strong as radiation efficiency suggests, and skywave will be a little stronger, which will reduce nighttime distant coverage quality slightly.  Still, it won't be much different from a 1/4 wave.

Of course, bandwidth will be less than that of a 1/4 wave antenna.  At 1680 KHz that may not be much of an issue, but down around 550 KHz it will matter.  The cage idea should help.

But aren't most BCB antennas a bit shortened, especially stations below about 800 KHz?  Seems to me that they all have top-hat stuff using the top section of the tower guys to tune them to frequency.

In the real whirl, for ham use, W2FMI has proved how well shortie [top loaded capacity hat] verticals can work on 40M.  These stand about 6' high or so

Also,  I know of a guy in NH who operates a four square of phased verticals in the DX 75M Window. They are 1/8 wave, loaded with coils in the center I think.  He consistently out hears the full sized vertical guys as well as some with wire Yagis into Eu.

These are kinda hambone antidotal stories, I'll admit, but modeling shows if the vertical is shorter than optimum, but with a good cleared area, good radial system and efficient loading and feed, they can be very close to a full sized perfect system.

I'd agree with Bacon about the change in pattern. No free lunches. It's not hard to match something and even make it efficient. But making it produce a desirable pattern in both the vertical and horizontal planes usually takes physical height and length, with few shortcuts.

If it were not the case, then everyone would have done it years ago and it wud be the standard today. [The exception is the Gotham Vertical - a mystifying oracle]

T

That might be an advantage for ham use, since most of us don't work each other by groundwave.  I think there may be three active stations within groundwave range of me on 160.  The increased skywave would  be an adavantage for the clear channel stations in reaching the distant edges of their secondary (skywave) coverage areas, at the expense of their primary local groundwave coverage.

...I KNOW MY MULTI-BAND/NO TRAP VERTICAL WERKS FB...CHEAP TO BUILD TOO....TIM....SK..