On my site you can find both the all copper 2 meter J-Pole antenna and an all copper 2 meter Slim Jim antenna. Both are great antennas, I don’t have a problem recommending either of them as the foundation for a amateur radio base station. But I often receive inquiries from individuals wondering if one antenna is better than the other. While I don’t think there is a best ‘universal’ antenna out there, I think some antennas are better suited for certain purposes than others.
With that aside, here are some unique benefits of the J-Pole antenna and the Slim Jim. Use this comparison chart to decide which is better for your intended purpose.
|Specs||J-Pole Antenna||Slim Jim Antenna|
|Antenna Type||Half wave vertical||End fed half wave|
|Matching System||1/4 wave J style match||1/4 wave J style match|
|Length||69 inches overall||58 inches overall|
|Bandwidth||4 MHz||7+ Mhz|
|Take-off Angle||20 degrees||8 degrees|
|Grounding||DC ground, no special grounding or isolation required||Needs to be isolated from the mast system|
Why would I choose a J-Pole antenna
J-Poles are a good choice if you are mounting the antenna at a lower mast height, or if you live in an urban area or valley. The omnidirectional radiation pattern and higher takeoff angle makes it easier to get a signal out if you are surrounded by buildings or rough terrain. Also, with the base of the antenna at DC ground, you can mount it on a metal or non metal mast with affecting the antennas performance. It also has a very low noise floor which makes the J-Pole an excellent receiving antenna for weaker signals. The J-Pole is an excellent antenna for satellite or International Space Station reception.
Why would I choose a Slim Jim antenna
The Slim Jim has a lower takeoff angle and more compressed radiation pattern. These two features of the antenna gives you about twice the gain as a standard J-Pole. A little more gain will make up for some of the feedline losses you’ll receive at VHF frequencies. Plus it will help stretch your signal out a little further. To really realize the benefits of the Slim Jim, you need to mount it in the air at about the 20-30 foot level. It will work well at lower heights, but the antenna shines when you get it up in the air.
Hopefully this chart helps in making your decision in choosing the J-Pole or Slim Jim antenna for your base radio station.
Does your 2m antenna also work on 70cm. I am new to the hobby my call sign is KK4FWE
Does your slim jim work on 440??
I have put the Slim Jim on the antenna analyzer and it does tune up in the 70 cm band. The SWR at 445 MHz was less than 1.5:1. So theoretically it will work on UHF. I have received quite a few reports from customers that are using the antenna as a dual band antenna, and the Slim Jim is performing quite well for them.
Since it tunes on 440, I’d be comfortable with using it on that band.
How does one apply lightning protection to an isolated antenna like the Slim Jim?
Since the Slim Jim antenna is isolated from the tower, the best place to add to lightning protection would be in the form of an arrestor where the antenna feed line enters the house. The arrestor is then grounded so that lightning energy can be shunted away from your radio equipment. Check out my article on lightning protection for more information: http://www.jpole-antenna.com/2013/03/29/lightning-protection-for-antennas/