Thanks for checking on QRZ.com I usually operate either portable or from a fixed station in Scotland although my home qth is Worcester, England. I enjoy experimenting with driven phased vertical arrays near the sea especially on the LF bands - 80m in particular. I use LC phasing and a dual trace CRO with current sensing to help adjust the array. To reduce the effects of salt spray I use vacuum variable capacitors and also vacuum relays but am still experimenting with "sealed" containers.
For the last four ARRL ssb contests I've operated on 80m from the Island of North Uist in the Outer Hebrides. In 2007 I used a 4square which suffered from inadequate F/B - a big problem on rx. But in 2008, 2009, and 2010 I used a 6square. This consists of 6 quarter wave vertical elements in a half wavelength square. One side of the square consists of three in-line elements spaced by quarter wavelength and quadrature fed with a binomial current amplitude distribution. This is duplicated on the other side of the square. This gives good high angle F/B - a bit better than a conventional un-optimised 4square and about an extra 2dB of gain. It's great fun setting up a phased array from scratch. Here's the /P 6square :
The main QRZ.COM picture is part of the 6square at the fixed station on North Uist looking to the NW. Next stop St. Kilda, then VO1 ! ! The plan is to add an extra 3 elements to make a 9square(see G3PPG entry on qrz.com). Here is the latest phase shift/matching network for the 6square :
Other plans at the fixed station include 4squares for 40m and 20m using half wave centre fed verticals. The 20m version has already been tested when I was operating /P on the island of South Uist a few years ago. Here I was abIe to bolt a short tower to the rocks.
Due to time constraints I didn't manage to get the tower vertical and tried to compensate by tilting the elements - aesthetically not too successfull It's best if the array is over the sea.
On one day summer 2006 W6's were S9 plus on this 20m 4square, but S0 and undetectable on a V-beam at 20m AGL beaming NW/SE (20m long legs). See the 6Y2A web page on www.k2kw.com.
There are also plans for 160m, 15m, and 10m antennas - all vertical arrays, of course, near the sea !
Some years I operate during the IOTA contest. Up to now this has always been a /P entry from South Uist.
Here are some photos from 2006 and 2003. The one on the left shows nested 4squares for 80m/40m. I found no measureable interaction although I had installed relays at the bases to open circuit or short the bases to ground. These relays have now been removed as they seemed redundant :
Here's a 2 element array on 20m using 5/8 wavelength verticals, spacing half wavelength, fed inphase or in antiphase. Much better performance to the Pacific short path than a V beam at 20m AGL. These were base fed with a pair of raised radials for each mast. No F/B of course with this system which is why the 4square version is preferred :
Both North and South Uist are EU-010.
Thanks to everyone who calls. Please only QSL direct. 73, Rick
Last modified: 2011-01-21 22:33:50, 4223 bytes
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