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The Broadside Curtain Aray

Presented by N0KHQ

(See "About feedline length" at bottom of article)

"I live on a very small residential lot 65' wide x 100' deep. I have a tree in the front yard and a tree in the back yard. The sterba is hung directly over the top of my house."
The bottom element of the array is up at 35'.
The design frequency for maximum gain was 28.5mhz.
THIS DESIGN IS FOR ALL BAND USE.... 160 THRU 10 using a Tuner!.

The standard formulas below were used
468/freqmhz = 1/2 wavelength section
234/freqmhz = 1/4 wavelength section.

My antenna elmer is W1VDE, Roger, He was part of the team that built the dishes at Arecibo, Puerto Rico years ago.
I am attaching the other half of my antenna system (
John is refering to the Tunable Radial System in pic below for your review and comments.) This system adds approx. 3db to 6db of additional gain to the Sterba.
If you need further information please do not hesitate to call.
Hams that have installed the curtain have liked it so much they have put up more than one."
John / N0KHQ / St. Louis
Always on 17M
"Antennas: You can build 'um better than you can buy 'um."

The Sterba Curtain, as designed is non resonant.There are a couple of bands where the swr will drop to 3:1.

The installation of the tunable buried radial system will help on 160m, 80/75m and 40m.
If I were you I would put out radials for those bands only.

4 for 160m
4 for 80/75m
4 for 40m

Remember, the radials should be cut at .15 of a wave not .25. There is a 10% shortening factor when radials are either on the ground or buried just below the grass level. By installing the radial system you will add 3db to 6db of gain to the gain on the curtain now. (ref. ON4UN - Low Band DXing)

I bought a HedgeHog from Lowes to dig the trenches $50 and used, what I call chain link fence wire ties, the aluminum wire ties are already bent in the shape of a "U" and hold the wire down very nicely.

You wont need to run an amplifier with the antenna for good performance.



This taken from recent email from John, N0KHQ
Hi Don,
Okay, here we go. Here's an example for 17 meters.
The Sterba is approx. 50' long x 16' high.

Example Gain on 17m:

17m squared / 12.56 (4pi) = 23 sq. meters of aperture

50' / 3.28 (1 meter) = 15.24 meters
16' / 3.28 (1 meter) = 4.878 meters

15.24m x 4. 878m = 74.34 sq.meters

74.34 / 23.00 = 3.24 log x 10 = 5.09 db + 1.64 (gain over dipole) = 6.73 db gain on 17m.

If you are running 150w x 6.73 = 1009.5 watts of effective radiated power output on 17m.

On 10m ( the design frequency) the gain is 10db +/-
The above formula can be used for calculating aprox gain on other bands

I need to clear up something that I may not have explained very well. This design allows a ham to use this array on all bands 10m through 160m, on 160m the swr bandwidth is pretty narrow.. There is no need to build arrays for different bands.
I have not tested other Sterba's designed for other bands as to their performance from 10m through 160m.


The reason the 450 ohm feed line is 130' is because it is about 1/4 wave length on 160m which is a high current point. So, what ever is tied to the end of the feed line.........is going to get out!.
For the feed line length (130') I have tried different lengths but 130' seems to be the minimum optimum length to get on 160 m.

I used 935/1.931=484.2' / 4 = 121.0' . This is a 1/4 wavelength at 1.931mhz, in the example. Some have said that 450 ohm ladder wire is actually 400 ohm. Some have said the velocity factor is not .95. Man, who really knows?

This antenna serves me well. Since I only have room for one.
A good thing to remember is the phrase "Volumetric Efficiency".

I have sent this design to a number of hams, the design has made it all the way to Europe. If you would like to contact a friend of mine that waS running this array his call sign is KB4CCM, Bill now SK. He liked it so well he put up two and gave away his other antennas!


" As John has told you, I have taken down all of my other wire antennas (dipole, extended double Zepp and Half square) due to the performance and versatility of the all band Sterbas. By the way, you may be interested in an article I wrote which is published in the ARRL Antenna Compendium # 7 now on sale. It is entitled  'The ODD QUAD' and details instructions on how to build a strong and cheap (using locally available materials) two element Quad that can be installed and rotated without a man made vertical structure. This Quad, along with the Sterbas, may be the only antennas I will ever need or use for the rest of my ham career."


The buried radial system that is used with the Sterba adds approx. 3db to 6db of gain. Once you add this gain to the gain of the curtain, the total gain of the antenna system is 9db to 12db of gain on 17m.

A good reference book that is available that will help hams to understand the importance of a good buried radial system is "Low Band DXing" by ON4UN cost $30.
Hams running the low bands are experts on antenna systems.
I call it my antenna bible. Hope all this helps........my head hurts!!!!!!! 73
John / N0KHQ / St. Louis Always on 17M

"Antennas: You can build 'um better than you can buy 'um." N0KHQ

Editor's note:
Many thanks to John, N0KHQ for sharing this information for all Hams to enjoy!
and to Bill, KB4CCM. If you have questions about this project please contact John, N0KHQ via email at:

John, N0KHQ   Email me here!

See John's 17 Meter Coaxial Moxon.
40 % reduction in size over standard Moxon

Click here

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