Radio operators typically want to get the best performance and range out of their antenna systems. VHF and UHF  propagation is typically line of site, so the common thought to increasing range is to increase the antenna height. For the most part this works, but when you look at the numbers, you will notice an decreasing rate of return for each foot that you increase in your antenna’s height.

To calculate range for an antenna such as the KB9VBR J-Pole antenna, you can use this simple equation to determine antenna’s receiving range over a flat surface: range in miles = square root of height X 1.42. An antenna mounted at 30 feet should have a theoretical range of 7.78 miles. Of course terrain and surrounding buildings and landscape can greatly affect this number.

You’ll notice that doubling the antenna height doesn’t automatically double the range. If you wanted to double the range, you’ll need to triple the height. In order to get greater and greater return in antenna distance, we need to increase the antenna height quite an appreciable amount.

It’s also worth noting that terrain makes a big difference in communications. These numbers are for a flat surface or over water. If you live in a valley or on a hilltop, you’ll find that your range will vary greatly. There are more sophisticated calculations that you can make to figure your antenna’s height above average terrain, and how high you’ll need to be to effectively communicate based on terrain. Increasing your transmitter’s power can also affect the range, using a 50 watt transmitter vs a 5 watt transmitter can affect distance greatly.

But this formula should give you a great ballpark estimate of the range or distance your antenna will experience.

I often receive inquiries if my antennas can be used with handheld or HT radios. The simple answer is that if your radio has a detachable antenna, then yes you can connect it to my J-Pole antennas or another style of antenna.

Connecting your HT to an external antenna is a great way to extend your range of the handheld, especially if you are using your handheld in a remote location. The duck antennas that come with most handheld radios are not very efficient, most have none or even a negative gain. They are designed for portability and not efficiency. If you wanted to set up a field station at a public service event, or even use your HT as a base radio, then you will need a better quality antenna, such as the 2 meter J-Pole antenna.

Handheld radios these days usually have an SMA or a BNC antenna connector on them. The J-Pole antenna uses an SO-239 connector on it, which mates to a PL-259 connector. The PL-259 is the standard connector for 50 ohm coax cable. You will need an adapter to connect your HT to the coax cable. Radio Shack does sell a BNC to SO-239 adapter. The part number is 278-120 and this should be a stocked item for most stores.  I know they also have an SMA to SO-239 adapter, but I was unable to find it in their online catalog. Radio Shack employees are not often well versed in the little components that they carry, so if you have the part number, your shopping experience will go better.

My favorite go to place for adapters and connectors is Tower Electronics. This online retailer can also be found at many hamfests in the the Midwest. When I run into them at a hamfest I’ll often pick up a variety of connectors and adapters that I may need for a future situation. They have both an SMA to So-239 adapter and an SMA to SO-239 adapter with a three foot jumper. For the SMA connector, I recommend getting the adapter with the jumper. This will take the stress off your HT’s connector and prolong it’s life.

These adapters and connectors will let you connect your handheld radio to standard 50 ohm coax cable so that you can use the J-Pole antenna with your handheld radio. This will not only increase the range of your HT, but also give you solid communications when using your handheld as part of a field station at a public service event. Start collecting adapters and keep them as part of your EMCOMM, emergency communications go-bag kit.

MURS or the Multi Use Radio Service is a license free radio service designated by the FCC for short range business and family communications. MURS has five channels in the 151 – 154 VHF MHz range that can be used. MURS has some distinct features that makes it very useful for a wide variety of communications:

• No license is needed for MURS communications
• Voice or data can be transmitted on the MURS frequencies
• 2 watt transmitter power limit for base and handheld communications, but no limit to antenna gain
• You can attach external antennas to a MURS radio, like the MURS J-Pole antenna.
• Antennas must have a max height of 20 feet.
• There are a wide variety of MURS radios available, like the popular Motorola RDM2020 handheld unit.

The best thing about MURS is that it is license free, so you can hand just about anyone a MURS programmed radio and not worry about the user having a FCC license.

What types of activities or groups are using MURS radios? MURS is great for search and rescue operations, coordinating volunteers at parades and community events, business operations and facilities, and personal communications. The radios are inexpensive and the MURS band is relatively uncongested, so it makes a great choice when other radio services may be loaded with communications.

Since MURS radios can use external antennas, but the antennas are limited to a 20 foot height, you’ll want to select a high performance antenna to maximize your signal range. The MURS J-Pole antenna is a great choice as it is lightweight, affordable, and very sensitive. The antenna’s wide bandwidth covers the entire MURS frequency range and the low noise floor will easily pick out a weak signal from a distant MURS station. Mounted at the 20 foot height, you can ideally expect a 5-10 mile range with your MURS radios, although surrounding buildings and terrain may affect performance.

Need more information about the Multi Use Radio Service to determine if its a right choice for your needs? Check out this MURS resource.

I recently received a Kenwood TM-281A two meter amateur radio transceiver as a door prize at last month’s state ARES/RACES conference. Well, last week I finally got the radio hooked up and put a few frequencies into it. General impressions: this is a very nice rig with clear audio, easy to use functions, and sensitive receive.

I’ve owned quite a few 2 meter and 2/440 rigs over the years from all three of the major manufacturers: Icom, Kenwood, and Yaesu. Each has their peculiarities and differences, but with everyone putting out quality products, it really all boils down to features and capabilities. With that being said, the Kenwood TM-281 delivers and easy to use, quality product. The radio is ruggedly constructed with a large heat sink along the back and bottom. I like the fact that the heat sink isn’t on the top of the rig. My Icom 2100 has a top mounted heat sink and that think filled up with dust and gunk after a couple of years of mobile use. Buttons on the rig are lit and big enough to push while on the road. The radio also has a very nice volume control and channel selector with detent clicks. Pushing the channel knob also access the setup menus.

Setting it up in my basement shack, I had it connected, programmed with one frequency and on the air in less than 10 minutes. The instructions are well laid out and the index quickly brought me to the section on where to program memories. But you can just as easy us it in the VFO mode as it has automatic repeater offset shift and enabling tone control was straightforward. The only thing I found a little cumbersome was using the direct entry keypad on the microphone, but it seems like this is a downfall on all the radios these days.

Audio on the Kenwood TM-281 is excellent, although compared to the audio on my primary base rig, the Kenwood TM-V7A, it seems a little tinny. The TM-V7a has a larger, top mounted speaker that give a fuller, richer sound. The TM-281′s speaker is smaller and front mounted, which is an advantage when the radio is mounted in a vehicle. Since I didn’t mount it in my car, I don’t know how the smaller speaker fares when up against the vehicle noise while on the road.

Out of the box, the Kenwood Tm-281 puts out 65 watts of power on high and 25 watts on low. This is great for mobile use as we usually run our mobiles on high power anyways. I’d love to see a more energy conserving 10 watt mode for low power base station use. I hooked the radio up to my 2 meter J-Pole antenna that I use for my secondary VHF and digital station. This antenna is mounted on a mast at about 10 feet. I had no problem picking out other mobile signals within at 10 mile radius on the repeater’s reverse frequency. The radio also has a built in weather alert function, and I scanned the weather band, picking up about 4 transmitters in a 60 mile radius. This rig definitely has a very sensitive receive. It also wasn’t bothered by my other rig while transmitting on a second 2 meter frequency.

The radio has up to 200 memories, but if you use the 6 character alpha tags for your memories, you will be limited to only 100 memory channels. 100 memory channels seems a little small for a radio in this day and age, especially if you travel a lot. My first 2 meter rig, an Icom 2100a, offered that many channels 10 years ago and I had it filled pretty quick.

All in all, I’m impressed with the Kenwood TM-281. It’s a highly capable, affordable amateur radio rig, and would recommend it to anyone looking for a starter radio or second rig for the shack or vehicle. I have  a feeling this one will eventually wind up in the wife’s car.

In the field, nothing beats the simplicity of a J-Pole antenna. I’ve seen quite a few J-Poles utilized for emergency and event communications; more so than any other type of antenna. With all the antennas on the market, why do hams always fall back on this type of antenna. There are several reasons:

1. Size. The 2 meter J-Pole is less than 6 feet tall. The breakaway model folds down to under 36 inches. The antenna is small enough that it can fit in the trunk of your car without taking up too much space.
2. Performance. The J-Pole has about 2.5db of gain over a 1/4 wave antenna. It’s a half wave design, so it has a doughnut shaped radiation pattern; sending more RF energy to the horizon than the sky. Also, building the antenna out of 1/2 inch copper tubing both increases the bandwidth and reduces the noise floor of the antenna. You’ll get better reception capabilities and a wider range of operating frequencies.
3. Cost. Probably the biggest factor; the J-Pole is inexpensive. You can dedicate this antenna to Emcomm use without breaking the bank. A similar single band commercial antenna is $80 or more; the 2 meter J-Pole is under $30.00.

As an active ARES/RACES member, the J-Pole is part of my go kit. If I didn’t recommend it, I wouldn’t sell it.

Its difficult to find a good base antenna for the 222MHz band. Many of the manufacturers have given up on this banc, which is a shame. This baby will get you on the air with great signal reports. Getting on 220 is like having your own private repeater or simplex frequencies. Overall length of 49 inches with an 11 inch mounting stub.

Price: $22.00 + 6.50 shipping

Low Power FM radio is taking off like crazy. If you are putting together a community radio station, special interest broadcast station or just want to transmit Christmas music to go with your holiday lights display, then this antenna is for you. This is a great basic antenna for your low power FM transmitter. The LPFM J-Pole is vertically polarized with about 3db of gain. The average height is about 95 inches but varies slightly with the frequency it is tuned to. The antenna comes in two pieces with a screw connector in the middle for easy transport and storage. When you order this antenna, please tell me which frequency you want it tuned to, as each antenna is custom tuned when built.

Price:  $44.00 + $10.00 shipping