Antennas

During last weekend I was playing with a temporary setup of an old Cushcraft 13B2 145MHz yagi that I had lying around. The aim was to try and decode some EME traffic with a simple station setup, but the old 13B2 did not yield any result. Then I decided to build a more efficient antenna by myself.
After considering many design options I decided to build a 12-El.-Yagi EF2012B modified for 50 Ohm-V and optimized by DK7ZB. Here is a preliminary progress report:

2016-08-22_17-18-20

Antenna schematics.

 

20160823_211911 (Large)

Antenna ready for the first VNA test on a stub, abt. 1 meter above ground.

 

on-ground

VNA results on a stub, abt. 1 meter above ground looks very promising.

 

20160824_061855 (Large)

Antenna mounted in my temporary setup, ready for new VNA test.

 

1 forsøk i rotor

VNA results not so good. I suspect that the elevation rotor is to close to the boom. I have to make a new rotor arm to get the rotor out of the way. …………….to be continued

LATEST UPDATE:

Been working on the matching problem all evening and it has nothing to do with the proximity to the rotor. It’s all about fine tuning this part, the radiator. Trimming the V-dipole length and bending angle does the trick.

Been working on the matching problem all evening and it has nothing to do with the proximity to the rotor.
It’s all about fine tuning this part, the radiator. Trimming the V-dipole length and bending angle did the trick.

 

Now it looks very close to the EZNEC simulation. I think there may be potential for better return-loss by some more fine tuning, but it is not going to happen tonight! 

Now it looks very close to the EZNEC simulation.
I think there may be potential for better return-loss by some more fine tuning, but it is not going to happen tonight!

MORE PIX.

From the rear.

From the rear.

It is not easy to find room for all this airborne metal in a small back yard.

It is not easy to find room for all this airborne metal in a small back yard. 🙂

 

After over nine years with the DK7ZB 4-Element-28-Ohm-OWA-Yagi with 2,20m-Boom I decided to do an upgrade. During about 7 hours work on August 19, 2016 I dismantled the old 2,2m boomer, recycled a lot of its parts and build a new DK7ZB 6-Element-50-Ohm-Yagi with 6,00m-Boom

Here are some pictures:

08:00 hour, boom lift in place.

08:00 hour, boom lift in place.

Working on the new 6-meter boom, old 2,2-meter on the floor.

Working on the new 6-meter boom, old 2,2-meter on the floor.

Populating elements.

Populating elements.

Antenna recipe :-)

Antenna recipe 🙂

Radiator is from the old antenna, but as this is a 50-ohm antenna the old DK7ZB match is replaced with a choke. Here I have 4 ½ turns, ID approx. 50mm. I threw in some surplus ferrite beads to, but I don’t know if they will do any good.

Radiator is from the old antenna, but as this is a 50-ohm antenna the old DK7ZB match is replaced with a choke. Here I have 4 ½ turns, ID approx. 50mm. I threw in some surplus ferrite beads to, but I don’t know if they will do any good.

Preliminary test to check if everything seems sane. MFJ-meter is happy.

Preliminary test to check if everything seems sane. MFJ-meter is happy.

Antenna in place, about 2 meters below the HF-yagi. Not a perfect location, but it is the best I can do for the time being.

Antenna in place, about 2 meters below the HF-yagi. Not a perfect location, but it is the best I can do for the time being.

VNA-check & the operator is happy with the results. Next is real on the air performance tests.

VNA-check & the operator is happy with the results.
Next is real on the air performance tests.