2 Meter Quick J-Pole Antenna

by admin 2 Comments

Being stuck at home during the COVID-19 outbreak I wanted to explore building a J-Pole antenna for the 2 meter band. I spend most of my “ham time” on the 2 meter repeaters in my area jumping on the local traffic nets.

The Virginia QSO party was starting that weekend so I built this as quickly as possible.

I had built one J-Pole before for GMRS frequencies (Call sign: WREY366) tuned around 465 MHz.

The design I chose came from the Oroville Amateur Radio Society in California website. Their posted J-Pole antenna design is shown to the right. I did need to adjust the connection points as expected. Mine have a bit more distance than the ideal specifications. The analysis is posted below.

As a quick test to see if my VSWR was on track, I held it together with duct tape! It was kind of just for fun but it actually worked surprisingly well. (I use a cheap radio for these tests).

Next was the soldering. I expected the VSWR to change because of, well, adding soldier and the end caps. Minor adjustment was needed at the hose clamps, but it wasn’t far off to start.

Next came the fun part. I used a kid’s bow and arrow set here to send fishing line up over the highest trees. I tied the ends to paracord and pulled that up, anchoring the first end to the ground.

Over the area I wanted the antenna to be fixed, I tied a loop in the cord to hang the antenna by fishing line as a separator to keep water off. Two additional ropes are added to prevent swinging and orient the “J” stub as desired for the repeaters I want to reach. The far end of the suspension rope is tied off with lots of excess so I can lower it as needed. I used split ferrite beads on the RF cable looped as a choke.

This is obviously a temporary construct but it seems to work exceedingly well. If I were to leave this up long term I would redo this with cable as the rope will decay in the weather (but I’d have to make sure it was far from the radiating element field as needed–maybe add rope only over the antenna section?). Also the antenna is not water-proofed. So far the rain it’s taken on doesn’t seem to interfere too much. The wind is more of a problem if it spins and moves around. Again, it hasn’t been too bad even in high (30 MPH) winds.

This was a quick project using what I had around the house. Paired with my Yaesu FT-2980 (pulled from the truck), I have been getting great range! I can now join nets and other 2 meter discussions from the convenience of my living room using my mobile radio.

SWR minimum at 146.800. Not too bad!
Lower end near 144.400 MHz still decent at SWR of 1.17. Curve looks dramatic because of scale.
Smith chart showing impedance of 49.0 ohms at 146.800 MHz. Pretty darn close to 50 ohms!
TX to WA4TSC repeater on uplink of 147.9 MHz. SWR of 1.04 double checked by a second meter
Courtesy Oroville Amateur radio Society
Quick test before soldering (it actually worked pretty well with duct tape!)
Time to solder it all together
Final connector bound with 14 AWG copper wire
Fun games: getting a rope in the air
RF Choke using split ferrite beads
Hanging about 40 feet above ground level and at 1,415 feet above sea level
Mobile radio on inverter in living room

Index: 3

Comments ( 2 )

  1. Kurt
    Love this! Heard you check in on the PSRG.org Net at 9am Pacific this morning. Happy Easter! Kurt / KC7DZQ
    • admin
      Thank you Kurt! Seems like a great group out there. As a University of Puget Sound Alumni, I am interested in staying in touch with the area. Thanks for stopping by! 73

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