homebrew 70cm oscar yagi

[KC4UMO]

First I like to thank the following.
N4CZT Doug, For getting me involed in Amateur satellite.

These guys helped me make my mind up on what I wanted to do.
K9STH Glen
KA4DPO John
WA9SVD Larry
KL7AJ Eric

W9GB Gregory, For helping me with some vital information


I been searching for months now trying to find a good design for a circular polarized 70cm yagi. All I could find is bits and pieces.
I took those bits and put them all together and this is the results.
This is a 10 X 10, total 20 element yagi.

Will edit this post as it moves along.
These first four pics shows how the boom is drilled.
I made a simple jig to hold the boom on the milling table.
Mark boom on two locations (vertical and horizontal). You and lay the boom in a piece of long angle iron to get it straight.

Align the bit with the mark and your hole will be at 90 degrees each time.

My boom is 1 inch x 72 inches.
All elements are 3/16 except driven. It will be 3/8"
Elements are insulated from boom. To reduce noise.
Driven element will have "gamma match"

Element length:
Ref- 12 15/16
drv- 12 3/4
D1- 11 15/16
D2- 11 13/16
D3- 11 5/8
D4- 11 9/16
D5- 11 1/2
D6- 11 7/16
D7- 11 3/8
D8- This one in still in question. 11 5/16 would be the next down step. 11 15/16 would blunt the pattern alot to take the sharpness off. 11 1/2 may be the better choice.

Spacing:
Ref= 0
Drv= 0-5 3/4
D1= 0-8 1/2
D2= 0-13 1/8
D3= 0-18 3/8
D4= 0-25 1/8
D5= 0-32 5/8
D6= 0-40 3/4
D7= 0-49 1/2
D8= 0-58 1/2

Horizontal plane will mount first.
Vertical plane will be shifted forward by 1/4 wave length.

Phasing harness will be two 75 ohm cables 1/4 wave length each.
Most antennas are on the same plane. You have to install a 1/4 wave length jumper to get circular polarization. You feed it 90 degrees out of phase.
Since the vertical elements at shifted forward 1/4 wave length (90 degrees electrical in space), the phasing harness is equal on each side, should give identical transformation of antenna impedance.