Building HighPerformance 1296 Yagis A guide for the

Building High-Performance 1296 Yagis A guide for the home builder Pacific Northwest VHF+ Conference (Sep. 2007) W 6 PQL 1

Debunking Cherished Myths One of these statements is correct. Can you pick it out? 1. Long Yagis Cannot Be Extended 2. Yagis Don’t Work on Microwave Bands 3. Yagi Element Dimensions are Extremely Critical 4. Long Yagis Have Narrow Bandwidths 5. You Can’t Feed a Long Yagi With a Simple Dipole 6. Bears make stuff happen in the woods Pacific Northwest VHF+ Conference (Sep. 2007) W 6 PQL 2

Reference material Pacific Northwest VHF+ Conference (Sep. 2007) W 6 PQL 3

Our Two Most Common Choices • Loop Yagis – First developed by G 3 JVL and others in the U. K. • Traditional Yagis – Later enhancements by DL 6 WU There advantages and disadvantages associated with both designs In their most common forms Pacific Northwest VHF+ Conference (Sep. 2007) W 6 PQL 4

Sample VSWR Measurements Pacific Northwest VHF+ Conference (Sep. 2007) W 6 PQL 5

Choosing the Design that Meets Your Needs • Decide what is important – Gain – Bandwidth – Out-of-band interference suppression – Ruggedness – Ease of construction – Cost – Aesthetics Pacific Northwest VHF+ Conference (Sep. 2007) W 6 PQL 6

Loop Yagi Construction Tips • Element fasteners • Fabricating the feed • Element thickness and width – correction factors • Matching techniques Pacific Northwest VHF+ Conference (Sep. 2007) W 6 PQL Data shown is from page 42 In the ARRL/RSGB International Microwave Handbook 7

Lock washers of the correct type (outside lock) are the key to securing the loops to the boom Boom area is here Pacific Northwest VHF+ Conference (Sep. 2007) W 6 PQL 8

An alternate way of attaching the driven element on a Loop Yagi Pacific Northwest VHF+ Conference (Sep. 2007) W 6 PQL 9

Supporting the feed Pacific Northwest VHF+ Conference (Sep. 2007) W 6 PQL 10

Traditional Yagi Construction • • A handy tool – VK 5 DJ Yagi Calculator Fasteners Feed options Matching techniques Pacific Northwest VHF+ Conference (Sep. 2007) W 6 PQL 11

Staking The Element to the Boom Staking dimples Pacific Northwest VHF+ Conference (Sep. 2007) W 6 PQL 12

A Folded Dipole and Balun as the Preferred Feed Element Shown here prior To weatherproofing Pacific Northwest VHF+ Conference (Sep. 2007) W 6 PQL 13

Driven Element Mount Pacific Northwest VHF+ Conference (Sep. 2007) W 6 PQL 14

Measuring Antennas • Beam width, f/b ratio and side-lobe suppression will tell the story • Home measurement systems • A semi-pro antenna range Pacific Northwest VHF+ Conference (Sep. 2007) W 6 PQL 15

Pacific Northwest VHF+ Conference (Sep. 2007) W 6 PQL 16

Data shown is from Page 9 -3 of the ARRL UHF/Microwave Experimenter’s Handbook Pacific Northwest VHF+ Conference (Sep. 2007) W 6 PQL 17

Pacific Northwest VHF+ Conference (Sep. 2007) W 6 PQL 18

• Extending the Boom to 8 feet Pacific Northwest VHF+ Conference (Sep. 2007) W 6 PQL 19

40 element DL 6 WU Yagi for 2304 Pacific Northwest VHF+ Conference (Sep. 2007) W 6 PQL 20

40 element Loop Yagi for 2304 Pacific Northwest VHF+ Conference (Sep. 2007) W 6 PQL 21

55 element Loop Yagi for 3456 Pacific Northwest VHF+ Conference (Sep. 2007) W 6 PQL 22

Reading the pattern changes as you move up the band (on 33 cm) Pacific Northwest VHF+ Conference (Sep. 2007) W 6 PQL 23

• And look what happens at the top of the band… Pacific Northwest VHF+ Conference (Sep. 2007) W 6 PQL 24

More Gain Required? • Should I Double the boom length? Ø 2. 35 db improvement if all goes well ØBoom support usually required ØIncreased lever arm (boom-mast mount) ØNarrower beam width (both E and H planes) Pacific Northwest VHF+ Conference (Sep. 2007) W 6 PQL 25

Stacking • You have More Choices – Control of E and/or H beam widths – Up to 3 db more gain, 2. 7 db typical – Dopt in wavelengths is 57/beamwidth – Compromise at. 9 Dopt Pacific Northwest VHF+ Conference (Sep. 2007) W 6 PQL 26