© Christoph Petermann DF9CY 1998

Last Update: 07 April 2009

A better view of the 6 element

I have mounted the 6 Element antenna about 2 meters above my 3 element antenna for 28 MHz. (The 28 MHz antenna is a well performing "EZNEC redesigned" CB radio antenna)

This plot shows the antenna "as seen" by the computer.

Here is a short description of my new SIX element antenna.
Design Frequency: 50.150 MHz

• Usable Bandwidth: 500 kHz
• Return loss: better than 10 dB within 500 KHz with 22 dB @50.150 MHz.
• Gain: > 11.2 dBi
• Front/Back ratio: > 12 dB
• Vertical sidelobe suppression: > 12 dB
• Horizontal sidelobe suppression: > 19 dB

Version List

• Version 1: Only a simulation version.
• Version 2: Has been published here. Version 2 has slightly changed element lengths and positions over Version 1. Gain has been reduced to 11.3 dBi, but it has an even better bandwidth performance. The first antenna of this type (Version 2) has been built by Hellmuth, DF7VX. It seems to work reasonably well. The design goal's resonance frequency has been hit exactly. Hellmuth is using this antenna since the 1998 Es season and worked a good number of DX stations with it. I have built a 2nd antenna and tried out a number of different feeds with it. This included folded 200 Ohms dipoles and Gamma matches.
• Version 3: This version was published here in July 1998. It has been built several times in England and America with good success.
• Version 4: The previous version suffered from having the resonance frequency a little low. I made some minor changes. This antenna is ready in operation here now and I am delighted with its performance in 12m above ground. It has a clean pattern with a good front/back ratio. SWR is excellent and broadband at least over the DX portion of the 6m band. It outperforms well the 4 element I have described here also.
• N7BW RealisationHere is a version built by John N7BW. The 6-ELEMENT and the FEED-POINT, at the driven element with an open dipole. (Images)

ELEMENT #	POSITION	center-to-end element length	Diameter
	Meters	Meters	Millimeters
Reflector	0	1.450	12
Dipole	1.114	1.385	12 folded dipole
1 st Director	1.585	1.328	12
2 nd Director	2.657	1.328	12
3 rd Director	3.942	1.327	12
4 th Director	5.327	1.320	12

Driven Element

• I strongly recommend building a folded dipole. I did have VERY poor experiences with Gamma Matches in the past. They are for low impedance antennas only and they provide the necessary transformation. So they are narrow banded and if you have not the high quality material at your hand, you will sacrificy some of your gain you have made the antenna for.
• A folded dipole needs a balun: take a good cable like RG400 teflon for it. The velocity factor of this cable type is 0.82; a length of 2.45m will do the job. It is expensive, but you want the DX, don't you?
• If you do not want to build a folded dipole, make an open dipole mounted insulated from the boom. A 1:1 RG400 transformer is built within 10 minutes and -voila- you have your antenna going.
• I designed the antenna for 50 Ohm (i.e. 200 Ohms if you have a folded dipole).
• TIP: Buy the complete folded dipole from KONNI Antennen in Esselbach

Elements
The diameter of the elements is 12 mm AND NOTHING ELSE. The antenna will not work, if you take something else. (J'espère, que c'est O.K., Jaques ?) The elements are mounted insulated above the boom. I have about 4 mm space from the boom to the elements. I use industrial spacers mounted with a 4 mm metal (!) screw centric to the 20*20mm boom. The deviation from an element being really isolated is minimal. Indeed I bought the whole element at KONNI Antennen. Buy reflector elements only and cut them to the given length.

BOOM
This antenna is calculated for a 20*20mm of 2 mm strength boom which I made from material from a metal shop and some scrap from Tonna 2m Yagis ...
I replaced the support boom you see on the image by a longer one. This gives more strength. In February 1999 the antenna survived a monstrous wind storm with gales up to 165 km/h.

Interactions
If you put this antenna on top (or below) your existing antennas: be aware that you reduce the antennas' performances. Keep this antenna at least 3.0 m away from ANY shortwave antenna and about 1.5m from other VHF antennas.

Stacking
If you are intended to stack 2 antennas, space them minimum of 1/2 wavelength. At half wavelength, the existing vertical sidelobes wil DISAPPEAR with a gain around +2.1 dB. Stacking the antennas at 1 wavelength increases stacking gain to about 2.7 dB and sidelobes go up. I would like to space 2 antennas at 1/2 wavelength, but the space on the tower is limited.

Performance
I have been reported and I can confirm myself: That antenna works. I see a clear pattern with the antenna up at 12m. There is almost no sidelobe and the F/B ratio is good. The SWR is also as expected.
It clearly outperforms the 4 element I did have up here through 1998. It is not more than 2.5 dB (or half a S-unit), but having more energy at the horizon gives you an extra advantage. The OZ7IGY beacon at 200 km line of sight is up about 2 S-units now (I am wondering myself ...) and the other beacon OZ6UHF at 300 km is also better now.
After a few months I can say, the antenna does a very good job. Tropo signals are often audiable over distances of more than 400 km.

After 2-1/2 years ... (May 2001)
I am still very pleased with the performance of the antenna. It withstood all brute gale winds here in my "seaside-resort". But 30 black birds (ravens) destroyed the antenna completely already twice. Now I have an 8 mm aluminium tube in the centre of on element strengthening against the weight of these birds. DX performance is better than everything I had before. I like the clean pattern. Certainly the front/back ratio of 12 .. 15 dB could be better, but you can have this by giving up the clean pattern and some gain. I know of about at least 12 hams having built this antenna and so far all are quite pleased with it. I would like to have a stacked version of two at a spacing of 4m, but my antenna tower is somewhat weak for that. My feedline is a 22m run of AirCell cable. I get a strong enhancement in noise when I turn the antenna across the galactic centre in summer. I had a low noise GaAs-Fet amp at the antenna for a while, but this was not necessary; so it is down again. In October 2000 I moved the antenna from 10.5m to 13m above ground level. The patterns became even cleaner and I succeeded in nice F2 QSOs to Far-East and the U.S.. The nicest thing however is to work the DX with a flawlessly well-performing homemade antenna.

Below are the diagrams for the azimuth plane (upper) and the elevation plane (lower). Sidelobes are barely visible in the azimuth plane and well 12 dB below maximum gain in the elevation plane. These are the free space simulations.

The SWR plot shows the optimum SWR at 50.110 MHz

This simulation shows the elevation pattern over real ground with the antenna mounted at 10 meters above ground.

My special thanks go to Roy Lewallen W7EL for programming this fantastic EZNEC 2.0

If you want to have more background knowledge on antennas and how-to make them, you will find an ultimate resource here:

W4RNL
L.B.Cebik W4RNL (+2008) ultimate ANTENNA Site. A must !

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