Prompted by G3ZQU (who has a pair of these in pieces) here are the aerial dimensions.
Bear in mind that this design is based directly on the (US) NBS (National Bureau of Standards)
Yagi Antenna Design research
set out in the mid '70s and it is single-optimised.
Alan's original manuscript comes out like this:
(interpreting his diagram: measure half sizes from tip to boom-side of the
fixed nut on the element sleeve bolt)
| MET Element # |
HALF-length * (mm) |
Element | Spacing (between) |
|---|---|---|---|
| R2 | 480 | R2 (x2) | |
| R1 | 497 | R1 | |
| D | 465 | DE | 275 |
| 10 | 463 | D1 | 410 |
| 9 | 453 | D2 | 410 |
| 8 | 446 | D3 | 410 |
| 7 | 439 | D4 | 410 |
| 6 | 431 | D5 | 410 |
| 5 | 431 | D6 | 410 |
| 4 | 431 | D7 | 410 |
| 3 | 431 | D8 | 410 |
| 2 | 439 | D9 | 410 |
| 1 | 446 | D10 | 410 |
- * Overall length of element must include 19mm for the boom.
-
- Boom Dimensions
- Originally, 3 sections with U-channel joiners on the rear ends of Front and Mid sections
-
- Front 1240mm (excl U-channel joiner)
- Mid 1647 ( ditto )
- Rear 1555
-
- Note that the U-channel joiners have holes for the relevant element to pass through.
- The sleeve bolt at the middle of each element secures the element to the boom and in two cases secures the boom joint.
-
- TO DO:
- Dimensions and subtended angle of trigonal Reflector supports
E&OE