This weekend marks the open of the 2012 Dayton Hamvention. The Hamvention is the world’s largest amateur radio exposition and flea market covering hundreds of acres in and around the six buildings of the Hara Arena in Dayton Ohio. This year’s Hamvention is scheduled for May 18-20, 2012.

At the Hamvention, the big name amateur radio manufacturers often announce new equipment and transceivers. Icom, Kenwood, and Yaesu are expected to make large product announcement along with the smaller radio manufacturers. As a general trend in the industry, the technologies to look for this year include digital operating modes and software defined radio.

Yet the meat of the Hamvention is the outdoor flea market space. This is where the deals can be found. Both new and used equipment dealers can be found along with scores of individuals who cleaned out their shacks and are hoping to unload it at the expo.

It’s about a 10 hour drive for me to attend Dayton. I haven’t made the trip yet, but one of the things on my bucket list is to set up a booth in the flea market and build and sell my 2 meter J-Pole antennas. Who knows, maybe next year I’ll get out there.

A very common question that I receive from people inquiring about my antennas is “Does a J-Pole antenna need to be grounded?” Of course there is a very easy answer: no and yes.

J-Pole antennas are half wave antennas by design. Actually they are a half wave antenna sitting on top of a quarter wave matching section. One great advantage of a half wave antenna that it doesn’t require any special grounding or a ground plane to operate. That’s why you’ll find half wave antennas mounted in difficult antenna situations, like on a boat or a vehicle roof made out of fiberglass. I’ve got a antenna I use on my bicycle that ‘s a half wave, because there really isn’t enough metal in the bike to make a effective groundplane.

As for the second half of the question: yes the J-Pole should be grounded. But instead of an RF ground, the antenna should have an electrical ground to protect it in case of a lightning strike. An electrical ground doesn’t enhance the RF radiation of the antenna, but it is an important safety feature on any installation. A simple electrical ground would consist of a ground line from the antenna either bonded to the tower system or run to a buried ground rod.

The lack of a groundplane makes it easy to mount this antenna just about anywhere. You could put it in your attic, on a chimney or a temporary mast. In fact the lack of a groundplane makes the J-Pole a great choice as an emergency or field antenna since there is less parts you need to assemble in deploying the antenna.

April 27 marks the birthday of Samuel F.B. Morse, the inventor of a single-wire telegraph system and co-creator of Morse Code. Thanks to his efforts, communications systems worldwide increased in speed exponentially.

Morse still has a visible mark on today’s communication. Amateur Radio operators all know ‘when all else fails’ morse code transmitted on CW will still make it through the noise.

Coil of coax used as a J-Pole antenna choke balun

Most of the instructions and plans you see online for J-Pole antennas often include the admonition to use a choke balun with the antenna. The purpose of the balun is to limit the amount of RF radiation coming back down the feedline and into the radio. Even though limiting the return of RF energy is a good thing, I still get the question ‘Is the choke balun necessary?’

To answer this question, you need to look at the antenna itself. The J-Pole is a half wave antenna by design. As a half wave antenna, it doesn’t require any special grounding or a groundplane to operate. The purpose of the groundplane is to ‘balance’ the antenna, that is to give the antenna something to push against as it releases the RF energy. For example, with a quarter wave antenna, not all the RF energy will be released up the antenna itself unless it has an effective groundplane to direct that stray energy.

Snap on ferrite chokes are a good alternative to the coil of coax choke balun

Half wave antennas don’t need the groundplane, but they also have the tendancy to send excess RF energy back down the feedline, increasing your SWR and limiting sensitivity. The choke balun, which can be as simple as six turns of coax or ferrite chokes near the feedpoint of the antenna will stop the excess RF energy from returning down the feedline.

If the antenna is perfectly tuned and is mounted in a location where it isn’t couple with any nearby structures, then the choke isn’t necessary. I’ve used J-Poles with and without the choke and a well tuned antenna mounted in a good location will work fine without out it. But as I usually say, the choke will never hurt and always help. Therefore I recommend the choke balun for any new J-Pole antenna installation.

On April 18, 1925 the International Amateur Radio Union (IARU) was founded. On the 18th of April the founding event is commemorated with the celebration of World Amateur Radio Day. There are over 700,000 ham radio licensees in the USA and about 2 ½ million worldwide. World Amateur Day’s mission is to spread the goodwill message of amateur radio.

The International Amateur Radio Union (IARU) is an organization consisting of over 160 national amateur radio societies around the world. Although individuals can’t join the IARU, the best way they can support the organization is by joining one of the national amateur radio organizations, such as the ARRL. Among the many activities the IARU does; the IARU sponsors World Amateur Radio Day each year in the spring. IARU member-societies are encouraged to take advantage of this special day to promote amateur radio in their country.

Take some time this World Amateur Day to get on the air, make some contacts and wish the person on the other end a happy World Amateur Day.

Brian of Anaheim, CA recently purchased one of my 2 meter J-Pole antennas for his shack. The antenna has installed on the chimney of his house above the DTV antenna. He’s put together a great story about the installation and operation of the new antenna. Head on over to his site to see more great pictures and some tips for installing the antenna on a television mast.

As for the performance of the antenna:

The acid test for the new J-Pole antenna was to see if I could hear the 2 meter Keller Repeater about 50 miles away. This is key for me, as it is the only direct radio link from my home to the mountain cabin in Wrightwood. I was able to hear traffic from the repeater, which was a pleasant surprise, as the line of sight is blocked by some nearby hills.

New Antenna Mounting

Often, amateur radio operators are looking for alternative locations to install their antennas. If you live in a space restricted location or are under a HOA restriction, you may be able to mount an antenna outside. This calls for a little creativity; if the space allows, consider mounting your antennas in the attic.

The advantages of mounting the antenna in the attic are twofold. Your antennas will be hidden from view, thereby not raising any issues with neighbors or others that would want to enforce any Home Owners Association restrictions that may be in your neighborhood.

A second advantage to mounting the antenna in the attic is that you will be protected from lightning strikes in the event of severe weather. the house will act as a natural shield and as long as your attic mounted antenna system is independent to the rest of your antennas, lightning won’t be an issue. This is great for the amateur radio operator that is providing net control activities during a SKYWARN severe weather activation.

Attic mounted antennas will work just fine and you will receive pretty close to the same results as you would if the antenna was outdoors. Most roofs have asphalt shingles on them, which won’t appreciably block RF radiation. If your house has a tin or steel roof, then the attic wouldn’t be much of an option.

The only concern with attic mounted antennas is the space available to you for mounting. The KB9VBR 2 meter J-Pole antenna is 69 inches tall overall. You will need a peak in your attic that is tall enough for the antenna to fit. If the top of the antenna touches the walls or roof, the performance may be affected slightly. If you attic isn’t tall enough, you could angle the antenna mounting to make it fit. Angling will affect the radiation patter slightly, so you may need to consider which directions to favor the antenna for the best reception.

Attic mounted antennas are a great solution for amateur radio operators looking for an effective VHF/UHF antenna system installed in a limited or restrictive situation.

The Chinese made Wouxun handheld radios have become quite popular with new and experienced hams alike. The price is right, around $125 for a dual band model, and they seem to work pretty well. From my experience fit and finish are a little lacking, but for an inexpensive handheld radio you can’t complain too much.

The rub with the Wouxun HTs is that their antenna connectors are reverse SMA. Unlike most amateur handhelds on the market, were the female end of the SMA is on the radio, Wouxun engineered their radios with the male end on the radio. This means that antennas and adaptors need to be reverse SMA if you want to connect an external antenna like the KB9VBR J-Pole antenna.

Since you need an adaptor to use an external antenna, regardless of the model of radio, the important fact is that the adaptor needs to be the correct style. Powerwerx, a retailer of Wouxun radios, such at the KG-UVD3 sells the proper adaptors that will work with all Wouxun models including the KG-UV3D, KG-UVA1, KG-833 and more.

Tower Electronics, my other go-to place for adaptors and connectors also carries the SMA Female to SO-239 connector and the SMA Female to BNC connector. Although I prefer an adaptor that has a short pigtail to it to take the stress of connecting stiff coax cable to the small connection on the radio.

I’ve also found the Reverse SMA or SMA Female adaptor available at Radio Shack stores and online. But with the constantly reduced inventory that most Radio Shacks run with these days, your mileage may vary.

Good luck with your Wouxun portable radios, I see they make a 2 meter and 222 MHz version thay may need to invest in.

UPDATE: Since writing this article a couple of weeks ago, I’ve received some comments and tips from other Wouxun users. Apparently not all reverse SMA connectors are created equal and some models work better than others on the Wouxun handheld radios. The generic connectors tend to stick out a bit and loosen up when you are unscrewing the antennas. But the ones designed for the radio, available form Powerwerx, fit and work perfectly with the radio.

As you can see from the comparison photo, the Wouxun adaptor is on the right, both reverse SMA adaptors look and work about the same. But the one designed specifically for the radio does not stick out so high, giving it a more stable connection.

Thanks Brian for your comments and pictures.

I receive a fair number of testimonials and positive reviews for my J-Pole antennas. Most of the testimonials can be found on the testimonial page or scattered throughout the site. But I thought I would highlight a few recent reviews that I received.

Hello KV9VBR, This is not a question but a testimonial. Last night I held QSO through a repeater in HARTSVILLE, TN. They are 122 miles from my location in Hazel Green AL. I was using 65 watts and the communication was so clear they were sure I was using a Yagi beam pointed at them. Not so! Just your J-Pole. It really works great.
KI4MBU

I was on eBay tonight and i thought i would send you a follow up message i bought my J-Pole from you a couple of months ago and a am really impressed by it’s performance. I am receiving pure signals on the railroad band more than 50 miles away and my transmitting power is about 35 miles sometimes better on a cloudy day. I just wanted to say how pleased I am with your product and if I ever need a new antenna i will definitely be buying it from you. Once again thank you very much.
Andrew

I just wanted to let you know I just left you a review over on eHam.net. I’m very pleased with the antenna you sent me a few years ago, and I’ll probably be ordering another in the near future. When I get some time, I’ll send a more thorough email for your web site testimonials as well if you’d like.

Thanks again for everything, and take care of yourself friend.
~~Mike ,KC8WRQ

You too can read my reviews on eHam.net or leave one yourself. I’d love to hear your experiences with a KB9VBR J-Pole antenna. If you have a question, comment, or testimonial, please leave it on contact form.

Are you a new Amateur Radio operator? Just received received your callsign and are now excited to get on the air.   Amateur Radio is a great hobby that will offer years and years of exploration, fun, and variety. Unfortunately there is a bit of investment to get ‘off the ground’ and start having fun.

The first radio most new ham radio operators purchase is a 2 meter or dual band handheld radio. These radios are inexpensive, full featured, and make it easy to start communicating on the local repeaters. The only downside is that handhelds are usually low powered at 5 watts. So they are great for portability, but unless you can get into the repeaters, they won’t give you much range. Attaching an external antenna like the KB9VBR 2 meter J-Pole antenna will increase your range and make the handheld radio a more effective tool for fixed position use. Here’s some advice on using a handheld radio with an external antenna.

Getting a mobile radio is the second step in building your amateur radio station. I’ve seen hams use their handhelds in the car or move their mobile radio between the car and the home to stay on the air. Get yourself a budget two meter radio for the car, and mount it permanently.

Don’t spend a lot of money starting out with ham radio. Get a few budget line or used pieces of equipment so that you have a chance to get a feel for the hobby and build a bit of experience. Then as you grow in knowledge, you will be able to start investing in quality pieces of radio equipment to do the job that want them to do.

The same applies to your antenna systems. The 2 meter KB9VBR J-Pole antenna makes a great first antennas as it is affordable and versatile. It will get you on the air and provide you years of service as you grow in the hobby. Plus when you replace it with a bigger antenna, the J-Pole will still make a great second or backup antenna.

Amateur Radio is a great hobby full of opportunity. I’ve been licensed since 1999 and still am learning and doing new things. Have fun, get on the air with a great antenna, and use the hobby to learn and meet new people.