Slim Jim vs. Traditional J-pole Antenna

Measured gain of SlimJIM and J-Pole

Real measurements of a Slim Jim antenna and traditional j-pole antenna reveal the truth about their respective gain and pattern.

Repeaters, Antennas & Trigonometry

You need an antenna with energy at high take off angles to hit the hill top repeaters… right? Well, not likely. Let’s review the details and do the math to understand what’s needed for VHF terrestrial radio communication.

5/8 Wave J-Pole vs. 1/2 Wave J-Pole EZNEC Shootout

Type “J-Pole” into any search engine and you will see dozens if not hundreds of plans to build your very own J-Pole antenna. Many are variations on the tried and true 1/2 wave design with the 1/4 wave stub at the bottom. Be it a plumber’s delight with copper pipe or ladder line heaven using a trimmed up 450 ohm feed line, many folks have successfully created their own J-Pole antenna with a surprising variety of materials.

However, there appears to be some kind of mystical attraction to the 5/8 wave radiator. Several of the J-Pole designs attempt to make the radiator 5/8 wave in length and adjust the phasing stub to make for a good match.

Let’s compare the two approaches using the models available from the late Larry Cebik’s NEC collection. Here are the contenders each using 3/8 inch diameter copper pipe…

Read more5/8 Wave J-Pole vs. 1/2 Wave J-Pole EZNEC Shootout

Collinear 5/8 wave J-Pole vs. Collinear 1/2 wave J-Pole EZNEC Shootout

While planning for a ham radio hike into the mountains to support the Appalachian Trail Golden Packet exercise, I asked my club members for ideas about a good portable 2 meter antenna.

One response included a link to this web page showcasing a collinear J-Pole antenna using two 5/8ths wave antenna elements.

Read moreCollinear 5/8 wave J-Pole vs. Collinear 1/2 wave J-Pole EZNEC Shootout

1/2 Wave vs. 5/4 Wave VHF EZNEC Shootout

A friend of mine is preparing for the upcoming Virginia QSO Party in March 2009. Part of the preparations include a focus on some good VHF antennas to support the heavy use of VHF mobile operations in this party. Vertical polarization is key to success. He spoke of a 5/4 Wave Antenna.

Unfortunately, one web site promoting a 5/4 wave antenna solution failed to realize you can’t make an antenna longer without eventually hitting a limit.

Read more1/2 Wave vs. 5/4 Wave VHF EZNEC Shootout