THE G4ZU....SPIDER BEAM......SKYPPER        
g4zu   G4ZU   skypper 234

This 3 elements wire Yagi comes along in a great variety of names. On the 11 meter we call it the Skypper due to the manufacturer Alex 1SD019
On Ham bands we call it the Spider beam or G4ZU.
What ever the name is its principle remains the same. It is a full-size 3 elements Yagi with the Director and Reflector bend towards the radiating element.
With this comes a small size Yagi with Gain 7,3 dBI and Front to Back in the order of 30 dB
It is easy to build, with the materials in front of me I had the first SWR test within an hour. And provided a great match within the 700 Khz bandwidth.
This is one antenna i will not get ride of...always handy for DX-expedition, Holliday or Back-up for home

radiation pattern                layout g4zu



The materials you need:                          parts g4zu






The fiberglass poles :
I used are fishermen tubes, each of a length of 4 meter lengths. You will need only about 2,5 meter of the fishing rod but the lower part of it is stronger therefor the antenna will stand through have wind. It is easy possible to make the framework from other materials, I have seen models made from bamboo aswell. 

The Teflon wire :
used, originally wash line Teflon...4 mm, but any NON-guiding wire is usable (perhaps from sailing boats thats extra strong)
The Electrical wire:
Any plain black and red 12 volt wire, or other form of electric guiding wire is good..(example: loud speaker wire )

U-bolts :
The U bolts we find on any old 27 mhz antenna are fine. You can also buy them at the local hardware store. Just make sure it fits the mast the beam is supposed to go on.

Aluminum tube:
The 1 meter aluminum tube has either fit INTO or AROUND the fiberglass poles in such a way that there is not to much friction.
Cut the aluminum tube in 2 pieces of 50 centimeter or 40 centimeter...no that critical.
- drill 2 holes close to the center of each tube. The sizes need to be large enough for the U-bolts ( see picture below)

MAKING OF THE FRAMEWORK: cross
    The first thing you should do now is put the U bolts though the aluminum tubes and connect the                     aluminum tubes to a mast.  Make sure you have about 30 centimeter of mast left above these aluminum         tubes.
    Connect the tubes above each other with 90 degrees difference. as shown in the picture
    Connect the 4 fishing rods to each open end of the aluminum tube. Now looked from above you should     see a cross.

   




MAKING OF THE ELEMENTS.:
Cut the electrical wires in pieces of : 5,25 meters (the reflector)
                                                       5,04 meters (the radiator)
                                                       4,84 meters (the director)
Take the reflector and put in the center of the reflector a little tape. This will help you determine the center of the reflector later.
The same counts for the director.
Take the radiator and cut it in half. You now have two pieces of 2,52 meter. uncover the sealing from both wires at one side for about half a centimeter.
Solder the uncovered electrical wires. Each independent. And enter them in the block-connector. This is your access for the coax. There are many more ways to attach the coax cable on it but this is about the simplest way.
solderingtensiontension on mast
What I did was take a small aluminium plate drill holes through it and used that for braking the tension.
tension with cross



PUTTING IT TOGETHER:
Attach the  radiator on the mast  about 30 centimeters above the aluminum cross. 
Connect  the Teflon wire (about 2x 50 centimeter) to the radiating dipool at both ends  the knobs  you can use for that  are as follows: dipool  knob  skypper2
This knob will tighten itself  when tension is brought on it.
Attach the  Teflon wires to the fishing rods they should be in a bowl position now.
Attach the other fishingrods...
Bend the fishingrods upwards and measure 2,5 meters from the Block-Connector. Put a tape around both fishingrods at that point. (this will be approx 2,6 meter)
Connect the Reflector (tape on tape) on a fishingrod. And connect the Director on a fishingrod (again tape to tape)
You could connect them with either wire or Ty-reps.
Bring the Teflon wires towards the fishingrod of the radiator and attach them at the same point where u attached the radiator.

Make some final small adjustments that a nice square is produced.

For long lasting results you could improve the coax connection, get rid of the Ty-reps and a paint on those fishing rods would not be misplaced.  

The cost I made for this project was in the order of 40 euro's I believe this could have been around 25...30 euro's simply because I bought fishingrods that were 4 meters long but 3 meters can do the trick aswell.
For the first time building you will probarbly need about 3..4 hrs to make everything right, thats not bad for an antenna that will work as good as any 3 elements yagi!

Any Questions pse mail!

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