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I have a 4 element 40M Bruce Array, up 7' on the bottom and 42' at the top. The elements are 35' and the end wires are 17.5'

I currently am feeding the antenna at the bottom center - as shown in the 20th Ed. of the ARRL Handbook - using a 1/4 wl counterpoise. I use an SGC 230 at the base so I can use it on multiple bands.

I just looked at EZnec and see that I will get better gain gain and TO angle's if I center feed one of the inner vertcals.

My question is - do I break the wire, insert an insulator and feed it like a vertical dipole? That's what I assume from the diagrams in the ARRL Antenna Book, but its not spelled out explicitly.

[WB6BYU]

Yes, you can break one of the vertical wires and feed
it at that point like a loop or dipole.  Keeping the
coax out of the pattern of the array may be a problem
(and the modeling software probably doesn't take that
into account!)

I'm puzzled by the difference between the two feed
methods, since in both cases the current in all the
wires should be the same.  How much difference is there?
Could it be the radial/counterpoise wire that is affecting
the pattern?  Try running it horizontally instead of
vertically to see if that changes things.  Also, make
sure you didn't model the existing feedpoint as a
series feed instead of a feed against ground - that will
certainly mess up the pattern!

You are right - both feeds work equally as well. The "alternate" feed suggested by the 20th edition of the ARRL Handbook as well as the "normal" feed. (Plus a really nice email response from Rudy, N6LF who wrote that section of the book). I broke one of the two inner verticals and then fed it with 30' of 450 ohm ladder line to my SGC 230 remote autotuner.

This isn't a better feed electrically - at least not from my on the air tests - (although EZNec shows that it should be significantly better), but for convenience sake, I was able to put the remote tuner and its coaxial feed in a hidden location under my deck. (When I had the SGC 230 right at the base of the center element) I had a mess of control wire and coax crossing a walkway - so that was a temporary / test installation.

If anyone would like the EZnec file for this - it is a really excellent antenna as a multiband 80 - 10M antenna. It has a DX (low) takeoff angle on all bands between 80 and 10M (except 15M), and has decent gain on all bands between 40 - 15M. Email me at my QRZ.com address. I am using it as my lowband DX antenna, and it fits like a glove!

This and my K1WA monoband array on 20M are pretty much the best combo of low and high HF band wire antennas that I can put up on my lot. (Height but not width restricted).

Thanks Dale . . .

[WB6BYU]

Personally I'd be interested in exploring why EZNEC
found a significant difference in the patterns.  I still
think it has to do with the way the feedpoint was
modeled somehow.

I would expect to see some differences on the other
bands with the different feed methods, but it shouldn't
be significant on the design frequency.

I'll take another look at my models in EZNec and see what I did. I do know that the antenna is performing well on 80 - 10M, but especially 40 and 30M, which is exactly what I wanted. I'm even snagging a few new band fills on 160M, where the antenna should be a "cloud warmer". Of course in the last few days the A and K have "calmed down", the SFI is up, and there are a number of dx-peditions on the low bands that are very strong. Coincidence? Probably.

A dx-pedition was a solid S9 here on 80M for almost 3 hours the other night - from 1 hour before sunset until just about 9 PM local time. I've never seen that before on 80M, and I earned DXCC on 80M earlier this year. African DX on 80M used to be a painful struggle for my little pistol setup, but I believe conditions were just out of the ordinary for 80M the other night. One of those super path openings.

I didn't seem to have the problem of close in stations being overly loud as compared to the DX - which can be a real problem with a lowband dipole or doublet that is not high enough (i.e 1/2 wl or more).
Only a few local stations in the massive pileup required that I switch in a narrow CW filter.

It does seem to be a "quieter" antenna than my single element horizontal doublet and short hatted vertical dipoles. Not quite as quiet as a loop (I've used K9AY loops before), but more like a loop than a dipole. Its a really neat antenna that takes up the same area as a G5RV . . . . and worth checking out.

I'll report back at the end of the DX season - because I believe you really need many months and need to go through almost a years cycle to get the "feel" for how an antenna performs. I use EZNec to make a decision on which antenna is worth trying, then its on the air experience that counts.

I once bought a really great commercial antenna after a fellow tried it for less than a week and pronounced it a dud. That week was one plaqued with solar flares and high angle noise. Patience is a virtue - hi hi.

Just a follow up - since there is very little posted info on the internet as far as the Bruce Array is concerned. The 4 element 40M Bruce Array (as described in the ARRL Antenna Handbook) is:

1) The best simple wire antenna that I have ever used
2) Excels on 40M, 30M, 15M and 12M
3) Is quite usable on 80M and 10M
4) Does not perform as well on 20M and 17M as my K1WA Array
5) Is quiet on receive - almost like a loop, but with a very good transmit pattern.

We have obviously had "variable" conditions so far this autumn, but I feel that I can't do better for a wire antenna that is only up 42 odd feet and that is only as "wide" as a G5RV.

It is a serious step up from the short hatted vertical dipoles and the G5RV's and ladder line fed doublets that I used during the "better" part of this cycle with great success.

Try this antenna - its really quite amazing!

Rich