Last Revision: 07 December 2012
This is the first working sample of the extended 6 element ZX-Yagi (now 7 elements) built by Sönke DL3LE
With a little additional material you are able to extend the ZX-Yagi 6 Elements for 50 MHz by about 2 meters. The gain rises about 0,8 dB.
The antenna is very rugged and heavy (ca 20kg). Hopefully this helps against the raven birds and the 160km/h wind gusts.
The antenna has been carefully calculated with EZNEC 5+. All dimensions differ slightly from the original ZX recommended sizes! The performance has been "tweeked" a bit.
The additional element makes the antenna to be over 8m long now. Therefore the antenna boom shall be supported by a rope for example.
You can take the dimensions from the wires spreadsheet below. Transfer these values carefully; it is your benefit.
Here are the dimensions of the 7 Element antenna for 50 MHz.
The centre portion of the elements has a diameter of 22mm and a length of 1880mm. The end portion has a diameter of 18mm. Take the length from the table above.
An antenna view from EZNEC.
Azimuth diagram. Note: For comparision you see the blue curve with the gain of the original 6 element antenna (ZX6-6)
Elevation diagram. Note: For comparision you see the blue curve with the gain of the original 6 element antenna (ZX6-6)
The 7 element antenna as it would perform at 9.6m above ground. (This is where the antenna could be on my tower - not very high though)
This stacked system is now working with a superb performance at DL3LE. Both antennas are at very low SWR each. The combined system has a very low SWR as well. Many DX stations which were out of range earlier could be logged already.
Two 7 element antennas in a stacked position.
Gain of the stacked antenna system over real ground simulation. The gain will be almost 20,8 dBi with a very good F/B ratio. The blue curve shows the gain of a single antenna at 20m above ground.
This stack will make a very good DX antenna. It performs best at very low angles - where the DX is expected. Vertical sidelobes are suppressed strongly. THIS also means that Sporadic E operating is not the first target of this antenna. You might experience even poor performance during Sporadic E openings. Eventually a second smaller antenna on a SEPARATE and eventually lower tower (10m) or roof might be helpful. DXers do this.
The first antenna is up "in the air" and is performing as expected.
I have tried to add one more element (You see I can't get enough) but this could NOT be done so easily. I have seen some additional gain, but the diagram has been spoiled heavily. The whole antenna must be recalculated then. So it did not work.