Frequently Asked Questions

You trade off durability and efficiency with a J-Pole antenna made out of wire or 450 ohm window line. Wire antennas are lightweight and can be easily packed when camping or hiking, but will not stand the test of time for long term base station installation. All Copper J-Pole and Slim Jim antennas will have more sensitivity, lower noise floor, and more bandwidth than a comparable wire antenna. The greater surface area of the copper tubing makes the difference.

The 2 meter J-Pole and Slim Jim antennas work quite well on the 70cm band. The SWR at 445 MHz is about 1.5:1 or so. The 70cm band is the 3rd harmonic of the 2 meter band so that’s why this antenna can work for dual band operation. The antenna works great for local repeater contacts and such on the UHF band.

The only issue is that it does have a higher than average RF takeoff angle, so UHF signals tend to be noisier than VHF signals. But 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 pretty well for them.

The 2 meter J-Pole antenna works well on the 70cm band because 70cm is the third harmonic of the 2 meter band. The frequencies line up well for dual band performance. Unfortunately this is not the case with the GMRS band. The SWR on 462-468 Mhz will be about 3:1 with the 2 meter J-Pole antenna. You could probably use the antenna on the GMRS band in limited cases, but I’d keep the power level down as low as possible.

My recommendation would be to use two antennas, the 2 meter J-Pole for 2m/70cm use and a second antenna for the GMRS band. This will give you your best performance.

As long as you don’t have a metal roof, you can certainly put the antenna in the attic. The 2 meter J-Pole antenna is 69 inches from tip to tail, so it can stand up in the attic, it should work. I have a video that talks more about attic antennas: https://youtu.be/c9Tu0g1-5B0.

Unfortunately I do not manufacture a J-Pole or Slim Jim style antenna for the 10/11 meter bands. A J-Pole for that band would be about 28 feet tall and even if broken down, be costly and very difficult to ship. I’ve got a video on how you can build your own 10 meter J-Pole antenna out of wire: https://youtu.be/RZv94BvNxrQ

I use UPS Ground to ship my antennas, with the exception of the VHF Slim Jim Antennas. Those are shipped USPS Ground Advantage. Alaska, Hawaii, and Puerto Rico are also shipped via USPS. At this time I do not ship to Canada or other international countries due to the high cost of oversize shipping packages. Related Post: Ordering Information

You may paint the antenna with nonmetallic paint to protect it and help it blend into the surroundings. If you want to keep the antenna looking shiny and new on the tower, you can also paint it with a clear enamel paint. As the copper J-Pole is exposed to the elements, it will develop a dark brown patina.  This dark tarnish or patina is only cosmetic and won’t affect the performance in any way.

I recommend the following procedure if you are planning to paint the antenna. First shine the antenna with some fine ’00’ steel wool. Then clean the antenna with a rag or paper towel soaked with isopropyl alcohol. Alcohol is flammable so do this in a well ventilated area. Also let the rag dry out in the open before throwing it away to prevent spontaneous combustion. Tape the connector up with masking tape and apply one or two coats of spray enamel paint.

Related Post: Painting the J-Pole Antenna

The J-Pole is a half wave antenna by design, so it does not require a ground plane or special grounding to function. You can mount it to either a metal or non metal mast without affecting its performance. Hose clamps or U-bolts work the best for mounting it to the mast. The J-Pole can be detuned by nearby large metal objects. You should keep it at least 6 feet away or above metal buildings and the like.

The Slim Jim antennas do benefit from using a piece of PVC to isolate the antenna from the mast. This is mainly because there isn’t a dedicated mounted spot on the antenna like there is with the J-Poles. I include a section of PVC and 2 hose clamps for that purpose. You can directly attach the Slim Jim to a non-conductive mast, though.

Related Post: Do J-Pole antennas need to be grounded?

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The J-pole is a great first antenna and it will work well with your Baofeng HT or other handheld radio, giving you excellent VHF and very good UHF coverage. But in order to attach an external antenna to your handheld you will need two additional items: an appropriate length of 50 ohm coax cable, and an adapter to connect the coax to the handheld. Here’s what you will need (in addition to the antenna) to connect your Baofeng HT.

You’ll want the antenna with the SO-239 connector. This video tells you more: https://youtu.be/DoKtRSLDY40 The coax and adapter can be purchased at amazon. Here’s one such adapter: http://amzn.to/2A5KQTq For a 50 foot piece of feedline, RG-8U would be the minimum I would recommend, otherwise LMR-400 is an excellent low loss coax. Since you are using your handheld radio, you’ll want a feedline cable that is highly efficient: https://amzn.to/2MFFHoQ

Related Post: Mounting external antennas to a Wouxun handheld radio

Related Post: Connecting an external antenna to an HT

Typically, the 2 meter all copper J-Pole antenna will handle 250 watts or more of power. J-Pole antennas have been designed and constructed out of a wide variety of materials, and the choice of construction materials can greatly affect the performance and power handling of the antenna. Copper is a very efficient conductor and will tolerate and dissipate heat energy very well.  I’ve personally tested my 2 meter antenna at power levels up to 170 watts without issue and am confident that the antenna will go higher.

Related Post: How many watts can a J-Pole antenna handle

If you mount the antenna 20 feet in the air, it would not be uncommon to be able to hear portable radios in a 2-3 mile circle, mobiles 5-10 miles, and repeaters up to 50-60 miles. VHF and UHF communications are primarily line of sight, your range will be dependent on antenna height, transmitter power, and terrain. If you live in a very hilly or urban area, these figures could be reduced.

Without knowing your location I recommend modeling coverage with programs like Radio Mobile: http://www.ve2dbe.com/english1.html This will give you a better, real world, estimation of expected range and distance.

Just to add some general context, with flat terrain, the curvature of the earth will limit a handheld signal with an antenna height of 5 feet to about 6 miles. To receive 20 miles of distance, you will most likely need to increase the height to about 30-40 feet and possibly increase transmitter power to about 25 watts or more.

Related Post: How does antenna height affect VHF communications.

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J-poles will certainly work well as a repeater antenna . They have an omnidirectional doughnut shaped radiation pattern and a moderate gain of about 3 dBi. This makes them a good choice as an antenna for low to medium elevation levels and would be a great choice as a remote base or receive antenna on a repeater system.

My Slim Jim antenna is a perfect choice for a repeater. It has a folded dipole design that gives it more gain and a lower angle of RF radiation, (7 degrees, vs 20 degrees). The Slim Jim concentrates more RF energy towards the horizon.

To further help in selecting a repeater antenna, ask yourself these questions? 1. Do you have a tower site in mind. Do they recommend or require a certain type of antenna. 2. What height are you planning to install the antenna. 3. Do you require a certain level of reliability. For instance will the antenna be installed in a location prone to very harsh conditions. My J-pole antenna can be used as a repeater antenna, and several repeater operators are using is for their repeaters. This particular antenna has about 3 db of gain, so it’s best suited for low level repeaters. That is, installed on towers at 120 feet or less. If you are going for a higher installation, then you will want a higher gain antenna that can better focus the signal towards the horizon.

Related Post: J-Pole and Slim Jim Repeater Antennas.

The standard option with my antennas is the SO-239, but you can also request an N Female connector. The SO-239, also called the UHF female connector is commonly used on amateur radio equipment and antennas. If you have a mobile radio, there will be an SO-239 on the back. If you are using an HT, you will get an adapter with an SMA on one end and an SO-239 on the other end. Then, the coax cable you’ll use will have PL-259 connectors on each end. The PL-259 mates to the SO-239.

N connectors have the advantage of being lower loss on VHF/UHF frequencies and  forming a water proof connection. N connectors are preferred by people running on UHF or microwave frequencies or using commercial equipment. So if you are using radios with N connections on the back, or have cable with male N connectors installed, then ordering the antenna with the N female connector makes sense.

But the vast majority of amateur radio gear uses the SO-239 / PL-259 combination and over 90% of my sales are for antennas with SO-239 connectors. So, the bottom line is, unless your particular needs require the N connector, order the antenna with the SO-239.

Coax cable selection for your antenna depends on the length of your feed line run and the frequencies you wish to transmit on. My general recommendation for VHF/UHF communication is: 25 feet or less: RG-8X. 25-50ish feet RG-8U. 75 feet or more: LMR-400. You can use a lower loss cable for shorter runs but I don’t recommend a high loss cable for longer runs.

Related Post: Coax Feedline Attenuation Chart

A loss of 3 db will cut your power in half. A six db loss will cut your power into 1/4. I recommend RG-8U if your cable run is over 50 feet and RG-8X if it is less than 50 feet. You shouldn’t use RG-58 for VHF/UHF unless it is a very short run (less than 15 feet.). GMRS J-Pole users should only use RG-8 for short runs and Belden 9913 for longer runs. Loss figures for other frequencies and cables can be found at the Cable Experts.

Here are a few things you can check if the SWR on your antenna is high.

1. Check the coax, make sure there are no problems associated with it. The connectors should be well soldered or crimped without any shorts and there should be be any apparent kinks in the cable.
2. Check the mounting location, nearby buildings will affect the SWR. Keep structures at least six feet away from the antenna, or make sure the antenna is above the structure.
3. Try rotating the antenna. Every antenna installation is a bit different and the antenna may be coupling with something. Rotating it can change the pattern and improve performance.
4. Make a balun to keep RF from coming back down the coax. Make a coil of about 5 loops of coax with a coil diameter of about 6 inches. This coil should be located about a foot away from the feedpoint of the antenna. Secure the coil with cable ties or electrical tape.
5. Inspect the antenna itself. Is the solder loose or cracked at the feedpoint. If it is, let me know.

My recommendation is to try rotating the antenna a bit and/or slightly adjusting the position of the hose clamps on the antenna. I’ve had several customers do these little tweaks and it made a big difference on how the antenna performed at their particular location.