How to Economically Stack Four 23cm PA1296-36-3BUT Antennas with Two VHF-UHF Dual Band Yagis PA144-432-19-3-2CB

Calculated needed distances for Economical Stack of Four PA1296-36-3BUT and Two PA144-432-19-3-2CB for EME. With Yaesu G-5500 Azimuth Elevation Rotator Systems. All Metal Pipes.

Original question:

I would like to get into EME (moon bounce), I do have limited space so 5-6 metre long booms are out, so my thoughts were to stack and bay 4 PA1296-3BUT antennas on a H frame, I can make the H frame from Glass fibre scaffold tubes and main mast from glass fibre. I need to remotely steer the antennas, however looking at the Yaesu G-5500 this is huge compared to the spacing of the antennas, I am concerned about having so much metal in the centre of the antennas. Please advise, is there a better option to the G5500 rotators.

I noticed the driven element phasing, I presume that the driven element can be turned around on the boom to get this correct. 

Can you also supply 4 electrically identical low loss cables to connect to the power splitter to the antennas……..

Also i been asked if it is possible to stack two PA144-432-19-3-2CB, I said probably not and operate on both bands, but said I would ask if there is a stacking distance that works for both 2m and 70cm, as it may be of interest to me and others here.

1296MHz Antenna "H" Stack PA1296-36-3BUT and Two VHF/UHF DualBand Antennas PA144-432-19-3-2CB G5500 Yaesu

Use Yaesu G-5500 Azimuth-Elevation Rotator Systems.

G-5500 Azimuth Elevation Rotator

First we will notice that there are two needed answers. One is referred to 23 cm antennas and second to dual-band 2m and 70cm antennas.

Simulated computer setup:

Computer Simulation 1296 MHz Antenna Stack PA1296-36-3BUT and DualBand Antennas PA144-432-19-3-2CB G5500 Rotator

Simulation was performed by using using the latest professional full-3D electromagnetic modelling software.

1. 23 antenna stack PA1296-36-3BUT on the left side of G-5500 rotator all metal pipes.

Again there are two questions we need to resolve. Distance from antennas to rotator and distance between antennas and horizontal metal pipe.

– Distance “B”

Test 1. We put right side of PA1296-36-3BUT antennas just 200 mm away from antenna tower.

Lower gain by 0.3 dB and distortion in antenna pattern occurs.

Computer Simulation 23cm Yagi Stack PA1296-36-3BUT Near Tower Pattern Distortion

Resulting gain 25.9 dBi (-0.3 dB)

Test 2. Distance “B” 300 mm. Gain 26.07 dBi (-0.13 dB)

Test 3. Disatnce “B” 400 mm. Gain 26.16 dBi (-0.04 dB). 

Test 4. Distance “B” 500 mm. Gain 26.2 dBi (0 dB).

We will conclude that 400 to 500 mm from metal parts of azimuth elevation rotator G5500 is good enough.

2. 23 cm antenna stack. Vertical distance. On picture marked as “C”.

Test 1. “Standard” 650 mm vertical distance.

Gain 25.9 dBi (-0.3 dB). Main offender is horizontal metal pipe. To near to antennas.

Test 2. Vertical stacking distance 700 mm. Gain 26.05 dBi (-0.15 dB)

Test 3. 750 mm vertical stacking distance. Gain 26.2 dBi (0 dB).


Horizontal distance from metal parts of rotator or tower of 400 to 500m is good enough.

Vertical stacking distance of 750 mm will produce excellent gain and good antenna pattern for four PA1296-36-3BUT antennas in stack.

On the right side we will put two Dual-Band 2m and 70cm Yagi Antennas PA144-432-19-3-2CB with two separate connectors. One for 2m and one for 70cm.

Unlike 23 cm antenna setup. There is no problem with horizontal metal pipe. Just problem with the distance “A”

Test 1. Distance “A” 800 mm.

2m 70cm DualBand Yagi Antenna Stack Computer Simulation PA144-432-19-3-2CB Near Tower Pattern Distortion 144MHz

Gain 15.15 dBi (-0.25 dB). Pattern distortion and bad SWR.

Test 2. Distance “A” 1100 mm. Gain 15.27 dBi (-0.13 dB)

Test 3. Distance “A” 1300 mm. Gain 15.35 dBi (-0.05 dB)

Test 4. Distance “A” 1500 mm. Gain 15.4 dBi (0 dB).

Final setup:

Four 23cm Yagi Antennas stack PA1296-36-3UT and Two VHF/UHF DualBand Antennas PA144-432-19-3-2CB G5500 all metal pipes stacking

With above distances there won’t be distortion in antenna pattern, gain and SWR.

After all intensive calculations we will conclude that with proper setup good power and preamplifiers you can work all three bands EME with other better equipped EME capable stations just with 6 relative small antennas.

For these calculations 30 computer and brain hours was spent.