If you’ve spent any time in the ham radio world, you know the standard J-Pole is a reliable “workhorse.” But what if you need more “reach” without switching to a complex directional Yagi? Enter the DIY Super J-Pole Antenna.
When it comes to omnidirectional antennas, the standard J-Pole is a legendary starter project. But for those who want to push their signal further toward the horizon, the DIY VHF Collinear J-Pole (often called the Super J-Pole) is the ultimate upgrade.
By stacking radiating elements and using a clever “phasing” technique, this design provides a significant gain increase over a standard dipole or J-pole, making it a favorite for builders who value efficiency and distance..
What Makes it Super J-Pole?
The “Super” J-Pole is a collinear variation of the traditional design. While a standard J-Pole uses a single half-wave element, the Super J-Pole stacks a second half-wave element on top.
The secret sauce is the phasing stub (the 495mm horizontal section in the diagram). Without this stub, the two vertical sections would be out of phase and cancel each other out. The stub ensures the current in both sections flows in the same direction, compressing the signal’s radiation pattern toward the horizon and significantly increasing your gain (typically by about 3dB over a standard J-Pole).
Super J-Pole –Key Dimensions
Precision is critical for collinear antennas. Using the schematic provided, here are the vital measurements:
- Top Radiator (983 mm): The upper half-wave element.
- Phasing Stub (495 mm x 2): This U-shaped section handles the 180 deg phase shift. The 43mm spacing between these horizontal bars is important for the impedance matching of the stub.
- Bottom Radiator & Matching Section (1485 mm total): This includes the lower radiating element and the primary J-match at the bottom.
- Feed Point (50–60 mm):This is where you tap your 50-ohm coax. Sliding these connection points up or down is how you fine-tune your SWR to a perfect 1.1:1.
Why Enthusiasts Prefer the Super J-Pole?
- Lower Take-off Angle: It pushes more of your signal toward the horizon rather than up into the sky, which is ideal for long-distance repeater work.
- Omnidirectional Power: You get high gain in every direction—no rotor required.
- No Ground Plane: Like the standard version, it doesn’t need radials, making it very easy to mount on a simple PVC or metal mast.
Build Tips
- Material: Most builders use 1/2″ copper pipe. It’s easy to solder and holds up well against the wind.
- Weatherproofing: Once you find the “sweet spot” for your feed point (50-60mm up), solder the connections and seal them with marine-grade heat shrink or liquid electrical tape to prevent corrosion.
- Mounting: The bottom “arbitrary length” section allows you to clamp the antenna to a mast without affecting the electrical performance of the radiators above it.
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