This 2m yagi antenna is light on the back-pocket and relatively easy to construct.
This project starts with an old VHF TV antenna purchased from a local ‘Green’ recycle depot for $5.00 AUD. The repurposed TV antenna was a Phased Array comprised of two aluminium booms and four elements or eight 1/4 wave elements. Each aluminium boom is 812 mm long (32 inches) and the 1/4 wave 10 mm elements are 760 mm long (30 inches). Unfortunately one of the four orange insulators is broken so I managed to salvage three. At this point I decided the rebuild would be a hand-held 2m 2el yagi comprising of a reflector and driven elements. This lightweight antenna will be ideal for SOTA purposes operating on 144.2 MHz SSB or 146.5 MHz FM.
The spare boom, two of the 10 mm elements and the single insulator will make an excellent 2m half-wave dipole, a project for another day. 🙂
I retained the solid 3 mm aluminium phasing wire and a nice collection of aluminium washers. The rusted bolts, nuts and washers are in the metal recycling bin.
To the 2m 2el Yagi
First I removed and discarded all of the rusted metal bolts, screws, washer and nuts. This step was aided by a generous coating of WD40 🙂
Next I removed one of the orange insulators by drilling out the center aluminium pop rivet. This insulator will form the basis for the reflector element.
Next I made an insulated right angle bracket for the feedpoint and BNC panel mount. The right angle bracket is made from a recycled 8 mm kitchen cutting board and bent using a heat gun and pliers. Finding the right amount of heat without melting the board into a puddle is tricky but nonetheless achievable. I got it right the first time 🙂
Feed point assembly
I mounted two solder tabs one on each driven element and replaced the old mounting screws with M4 50 mm long stainless steel screws, washers and nuts. To start with I cut each of the two 1/4 wave elements to 490 mm long (a little over 19 inches). The rough guide is: 300 / frequency x 0.95 x 0.25. Therefore 300 / 144.2 x 0.95 x 0.25 = 494 mm. It’s a start point and doesn’t take account of the material diameter. Each element will be trimmed evenly in the tune up stage.
I cut the reflector elements so that the total length (start point) is 1020 mm wide (40.15 inches). I used a section of the 3 mm aluminium phasing wire clamped between two aluminium washers to electrically join both elements. Both elements are insulated from the aluminium boom. The insulator is secured to the boom with a M5 40 mm long stainless steel bolt, washer and nut.
The position of the reflector element will be determined in the tune up stage. Having the flexibility to slide the reflector element along the boom greatly assists with finding the low VSWR for 144.2 MHz.
Layout – assembled hand-held 2m 2el yagi antenna
Final measurements after tuning
- Reflector Length: 976 mm (38.42 inches)
- Driven Elements: 2 x 463 mm (18.22 inches) which includes the length of the solder tab. At 144 MHz every millimetre counts 🙂
- Spacing: 430 mm (17 inches), 0.21 wavelength
- Gain: 4.5 dB
- VSWR 1.04:1 @ 144.2 MHz
- 1.5:1 VSWR @ 146.7 MHz
- Total Weight: 400 grams (14 ounces)
- Total cost with new stainless steel bolts and a BNC panel mount: $20.00 AUD
While the optimal VSWR is in the narrow mode (SSB, CW and Digi) segment of the 2m band, I will also use this antenna on 146.5 MHz FM, the VK 2m simplex call channel where the VSWR is under 1.5:1.
AntScope – AA-600 Return Loss graph
YagiCad Radiation Pattern
I plan to use this antenna for portable operations only. If you want to mount the antenna in the weather then consider waterproofing the feed point.
Ferrite beads will be used to make a current choke.
Post update 8 March 2022 – I have glued a section of 19 mm hot water pipe insulation on the boom to form a handle. The insulation will be welcome during cold winter mornings on the peaks.
Thanks for taking the time to read this post and good luck with your homebrew antenna construction.
Last Update: 8 March 2022