Radio Frequency (RF) & Wireless Design

Created by Steven Minichiello on 27 April, 2018

The most common antenna is probably the mobile vertical for vehicles and also used on handheld transceivers, and WiFi routers, but for amateur radio the most popular antenna is probably the dipole for HF work.


But when it comes to VHF and UHF operation, especially for home use, the most ubiquitous do-it-yourself antenna is probably the J-pole : https://en.wikipedia.org/wiki/J-pole_antenna


The J-pole antenna is 1/2 wavelength vertical with a 1/4 wavelength impedance matching stub which provides a phase offset that will null any signals below the matching stub, effectively radiating above the feed point.

The super J-pole has a 1/4 wavelength phase stub near the top to compress the vertical beamwidth, thereby increasing the outward directional gain. Adding another 1/4 wavelength phase stub will compress it even further, similiar to parasitic elements on a yagi directional beam antenna.


I have designed what i call a super-duper J-pole antenna to provide such a narrower beamwidth based upon one that i found on the web :

For those wishing to investigate more on J-pole antennas, here's a good link to many projects, including the copper pipe variety : https://www.dxzone.com/catalog/Antennas/J-Pole/