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Small Backyard; Big Signal -- Shrunken 40 Meter Phased Quads:

from Bob Raynor, N4JTE on September 12, 2013
View comments about this article!

"Editor's Note: Due to the popularity of some of eHam's older articles, many of which you may not have read, the eHam.net team has decided to rerun some of the best articles that we have received since eHam's inception. These articles will be reprinted to add to the quality of eHam's content and in a show of appreciation to the authors of these articles." This article was originally published on: 05/20/2011





Small Backyard; Big Signal -- Shrunken 40 Meter Phased Quads:
By Bob Raynor, N4JTE

Let me state this up front, this is not an antenna project for the faint of heart, nor does it describe an all band, miracle working, coax fed multi DX pile up buster.

It is however a 2 element small footprint 40 meter phased, reversible, downsized quad array that surprised me big time and I am Real picky. So that’s what I am going to describe here with the hope that someone out there will find the same enjoyment I get from this sucker.

I began this project with a lot of unknowns that could only be proven after I built it. This one is way beyond my modeling abilities so real world backyard testing was the only way to go.

How do you shrink 2 full size quads without killing the gain and bandwidth? Is there any way an almost ground mounted diamond shaped quad array will do anything?

Lastly, the big question, could I use a very successful reversible phased vertical Christman, (ON4UN) method of feeding to get that gain and front to back I enjoyed with phased verticals at ¼ WL spacing.

Well the easy answer is a big Yes and then some. Let me preface everything to follow by stating that this monoband design can be used on any band when extrapolated dimensions are applied. Thanks to Mr. Cebik, sk, I read of a way to capacity load a quad and shrink it in all dimensions by 25% a substantial amount when space is at a premium. He added the extra wire in two horizontal dimensions.

That was my first attempt and it was a nightmare to build with all the floppy wires and anchor strings but it tuned to 7.080, exactly where he predicted, but way too tricky and flimsy to build. My radio was in surgery so I had free time to try a different, hopefully, simpler configuration.

I killed two birds so to speak and attached the capacity load wires to the 40 ft fiberglass center pole and went for vertical polarization by feeding an outside corner to avoid the high current points at the top and bottom corners of the cap wires and possibly screw that up. To be honest it was all guesswork!

Ended up with a much more stable and doable design but would it change anything drastically? Actually no, but for some reason the frequency dropped to 6.9, I did not bother changing anything until the other element was installed, mutual impedance you know!

So I put the second quad up with the exact same dimensions and watched this experiment blow around in 35 mph winds before checking each for resonance.

Long story short, a little pruning got me to 7.150 on both. I hooked up the previous phaselines to the outside corners and checked at the radio. I got a 1.7 swr in each direction, workable with no tuner required.

Front to back was around 4 S units. Usable bandwidth is from 7.135 thru 7.185. The ability to work Corsica and then, with a flick of the switch, contact a Columbia, SA station is a lot of fun especially when both stations report a “booming”5-9 plus signal report. Rig is IC 735 with AL 811H at 400 watts.

Bottom line is that I am writing this at 3am after spending another fun night working NE and SW DX stations at will on first call. Often I am the first station to place the DX station on the summit and that’s a trip! The quad array is surpassing all expectations and I am very happy with the perceived gain and front to back, subjective I know but this design is gonna be here to the next “Big Idea”.

What I Learned:

1: The Christman, ON4UN reversible system works great on quads not just ¼ WL phased verticals.

Expert waterproofing, Not! See www.n4jte@blogspot.com for phasing details.

2: A quad correctly shrunk by 25% will do a very credible job on 40 meters if DX is your thing.

3: Vertical polarization on a quad is worth the effort especially at low heights in a diamond configuration.

4: This array outperformed a 40 meter EDZ at 60 ft. the later it got on the band.

5: It is better than a 2 element vertical array previous installed on same poles and much quieter than expected with local QRN.

FINAL THOUGHTS:

As I said, this article/project is not for everyone and probably will end up in the “what’s next” category but if you are trying to work DX in two opposite directions with a signature, consistently strong signal, I guarantee you will be astounded with the results on 40 meters at such a low cost and if modified will work as well on your band of choice!

Tnx for reading,
Bob the Builder
N4JTE

Member Comments:
This article has expired. No more comments may be added.
 
Small Backyard; Big Signal -- Shrunken 40 Meter Phased Quads  
by KD8GEH on September 12, 2013 Mail this to a friend!
Hi Bob,

Another good one! Keep up the good work... this ones going in my ta-do book ... but after the wire beam.

73 Dave KD8GEH
 
RE: Small Backyard; Big Signal -- Shrunken 40 Meter Phased Q  
by K9MHZ on September 12, 2013 Mail this to a friend!
The first two sentences are a hoot! Finally, a guy with some balanced perspective, instead of: "look at my super duper 5/9 to Antarctica antenna!"

Nice project.



 
Increasing complexity is not always the answer.  
by AI2IA on September 12, 2013 Mail this to a friend!
"Let me state this up front, this is not an antenna project for the faint of heart, nor does it describe an all band, miracle working, coax fed multi DX pile up buster." - so begins the author.

My comment is addressed to those who seek an antenna of few components, capable of withstanding rough weather, of low cost, and quick and easy construction and installation that will still provide satisfaction.

If you have a flag pole or a tree or are willing to put up a vertical support, the inverted vee wire antenna cut for the 40 meter band will give you years of satisfaction and offer the opportunity to tune other bands as well.

Since it is a simple antenna, if you take care to do the details with the best workmanship and quality as you can, and take your time in doing it, you will not be disappointed.
 
RE: Increasing complexity is not always the answer.  
by N4JTE on September 12, 2013 Mail this to a friend!
Ray appreciate the comments, I have written a few basic antenna articles previously on eham and understand your viewpoint.
This build was quite awhile ago and I had no idea it was on here again, definetley not for beginners but does present some good theory on linear loading/ saving space and phasing for intermediate wire antenna builders.
I have moved on to the next big idea and presently using phased reversable dipoles that exceed any wire antennas to date in my experiments.
Bob
 
If you can put it in your backyard, they will come  
by AI2IA on September 12, 2013 Mail this to a friend!
In my concern for the new hams, the low budget hams, and the hams with limited time after work hours and the exhausting commute, I forgot to mention that the Shrunken 40 meter Phased Quads article is a very alluring one.

For those a little further up the ladder it looks like a great take-your-time cool weather project, one from which you can take a great deal of satisfaction once you have it up and running.

I'm very happy to see it make its second appearance on the site. Thanks, Bob! Goodness knows that small backyards are one of the big challenges some of us have to confront.
 
Small Backyard; Big Signal -- Shrunken 40 Meter Phased Quads  
by K3VAT on September 13, 2013 Mail this to a friend!
thanks Bob, nice article!

I may of missed it, but what was the height above ground (at apex) of the quad? Did you manage to work into SE Asia (Vietnam, Laos, Cambodia, etc) from your QTH with this antenna? 73, Rich, K3VAT
 
RE: Small Backyard; Big Signal -- Shrunken 40 Meter Phased Q  
by K3VAT on September 13, 2013 Mail this to a friend!
I just checked the diagram and see that the antenna was mounted atop a 40' fiberglass pole. thanks, Rich
 
RE: Small Backyard; Big Signal -- Shrunken 40 Meter Phased Q  
by N4JTE on September 13, 2013 Mail this to a friend!
RR Rich, always appreciate your comments here and on the forums for others, you nail it when responding to their questions, when your there I hold my tongue, lol
No need to pile on, hi
Bob
 
Small Backyard; Big Signal -- Shrunken 40 Meter Phased Quads  
by RSHIRE22 on September 15, 2013 Mail this to a friend!
Seems to me 20 meters would be the band of choice since every dimension is one half.

Duh?
 
Small Backyard; Big Signal -- Shrunken 40 Meter Phased Quads  
by KK0DJ on September 25, 2013 Mail this to a friend!
Hey Bob... great article. I really enjoy the articles that are do-able and enjoyed the manner in which you constructed it and how well it plays. Makes me think of a square of 'em - one array to point E/W and one to point N/S... but the Iowa winter is coming soon ... maybe next Spring!
73
Dennis
KK0DJ
 
Small Backyard; Big Signal -- Shrunken 40 Meter Phased Quads  
by N2LEE on October 15, 2013 Mail this to a friend!
Bob, thanks... another good antenna article.
 
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