Yup, we built a 2-element directional Yagi antenna in class.

  • Over the course of two club meetings, we cut the elements of the antenna and assembled this following plans provided here:

    https://www.instructables.com/DIY-5-Portable-VHF-Yagi-Antenna-for-the-2-Meter-Ba/

    whole antenna

    connections

    SWR (Standing Wave Ratio) was very nice after one adjustment. We shortened each driven element by 6mm on both sides and achieved an SWR of 1.03:1 at 147.1 MHz. May adjust slightly to be more in the center of the band, or see if we can get lowest SWR at the 146.52 MHz (National Calling Frequency for 2m).  We have below 1.2:1 for the entire 2m band.

    reading

    A helpful document to explain SWR can be found here https://www.arrl.org/files/file/Technology/tis/info/pdf/q1106037.pdf and for those just learning, Page 1 is the most of what you need to know. SWR is the ratio of forward moving energy (from the radio, through the antenna, out into the atmosphere) to reflected energy (coming back down the cable toward the radio).  

    You'll notice in the display that they don't display the ubiquitous ":1" or "to one" part of the ratio. 1.03 on the display means a ratio of 1.03:1.  The goal is to get the antenna tuned to the lowest SWR. 

    Side note, this wasn't a "$5 antenna" as described. It cost a little bit more, like $29.90 for parts from our local hardware store and a donated length of coaxial cable.

    (Qty 4) 3/16" threaded rods, 36" long, at $4.99 each = $19.96

    (Qty 1) 3/4" x 48" hardwood dowel, at $4.59 each

    (Qty 2) 3/16" butterfly nuts at $0.99 each = $1.98

    (Qty 3) coupling nut at $0.95 each = $2.85

    (Qty 4) 3/16" nuts at $0.13 each = $0.52

    Coaxial cable with SMA connector - donated 

    Two element Yagi:

    yagi diagram