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Antenna Projects

Here you'll find documentation for my various homebrew antenna projects, including designs of others and my own, performance notes, and lessons learned.

Current Projects​

WE7OMG Pockrus Open Stub J-Pole (Joystick™)​

  • Designer: WE7OMG (Carl Pokrus) / NT1K (Jeffrey Bail)
  • Type: Dual-band 2m/70cm Open-Stub, Half-Wave J-Pole

Technical Overview​

Technically, the Pockrus™ J-pole Joystick™ antenna is a dual-band (2 meters and 70 cm) open-stub, half-wave J-pole antenna. As a vertical radiator, it has a flattened-donut omnidirectional pattern, sending a radio signal fairly equally in all directions parallel to the earth.

Construction​

  • Materials:
    • Solid aluminum rod stock (3/8" diameter)
    • Aluminum angle brackets for mounting
    • Stainless steel nuts with Loctite™ to prevent accidental loosening
    • Threaded rods for secure assembly
  • Connector: SO-239 (UHF) stud for connection to 50-ohm coaxial cable
  • Design Features:
    • Open Stub design for improved bandwidth and performance
    • Pre-drilled mounting holes for easy installation
    • Weather-resistant construction with proper sealing to the SO-239 connector

Performance​

  • 2m Band (144-148 MHz):
    • SWR: 1.1:1 or better
    • Gain: 2.6 dBi (measured over real earth)
    • Radiation: Flattened-donut omnidirectional pattern
  • 70cm Band (440-450 MHz):
    • SWR: 1.3:1 or better
    • Gain: 5.2 dBi (measured over real earth)
    • Radiation: Flattened-donut omnidirectional pattern
  • Power Handling: 1500W PEP
  • Bandwidth: Covers entire 2m and 70cm bands, compatible with GMRS frequencies

Note on Gain Measurements: The gain values listed are measured over real earth conditions. When comparing antenna gains, it's important to understand that a dipole over earth at optimum height has approximately 8.5 dBi gain (not the often-cited 2.15 dB over isotropic). The J-pole's gain of ~2.6 dBi on 2m is comparable to a 1/4 wave ground plane antenna (2.69 dBi). For more technical details on J-pole gain and performance, see W8JI's End-Fed Vertical and J-pole Analysis.

Features​

  • No radials or ground plane needed
  • Omnidirectional radiation pattern (flattened-donut)
  • Improved bandwidth over traditional copper J-Pole designs
  • Simple construction with common materials sourced from local hardware stores and online
  • Secure assembly with stainless steel hardware and thread locker
  • Usage:
    • Local repeater access
    • APRS operation/ Winlink
    • Simplex communications
    • Emergency communications
  • References:
  • Images: WE7OMG Pockrus Open Stub J-Pole - Front View WE7OMG Pockrus Open Stub J-Pole - Side View Images courtesy of NT1K.com

Installation​

  • Install the J-Pole on a 1/2 wave vertical (12.5 ft or 3.8 m)
  • Use a 50 ohm coaxial cable to connect the J-Pole to the radio
  • Wrap the coaxial cable in 5 turns of LMR-400 to create a ugly but effective RF choke, this helps keep RF from returning to the radio. This antenna suffers from common mode current, so the RF choke is important.

End-Fed Half Wave (EFHW) Antenna​

  • 40m-10m multiband configuration
  • Homebrew 49:1 unun
  • Lightweight and portable for field operations

Magnetic Loop Antenna​

  • 20m-10m coverage
  • Vacuum variable capacitor tuning
  • Remote tuning system in development

Yagi Antennas​

  • 2m/70cm dual-band Yagi for satellite work
  • Portable 6m Yagi for VHF contests

Future Projects​

  • NVIS antenna system for regional communications
  • Hexbeam for HF DXing
  • Portable vertical antenna for SOTA activations

Resources​

Last Updated: October 2025