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.

As I write this, we are in the midst of one of the most mile winters that I can remember. Our snow cover in northern Wisconsin is only inches deep and in fact I have quite a few bare spots on my lawn. With temperatures soaring into the 40′s (in January, no less) the snow really doesn’t have a chance.

Although the warm temps and mild weather is putting a damper on the outdoor snow activities, you can take advantage of the warm temps and beautiful sunny days to inspect and upgrade your antenna systems. Instead of climbing the tower when its unbearably hot, use this time to put up a new 2 meter J-Pole antenna. Or replace an aging antenna with something newer and better performing.

Did you get a new scanner or amateur radio transceiver for Christmas? Get it on the air with a base station antenna. Our J-Pole antennas make great scanner antennas, especially for the VHF public safety spectrum. My MURS J-Pole antenna is an ideal public safety antenna and will also perform double duty transmitting on the MURS radio band. Same story with the Marine Band J-Pole antenna. This antenna is tuned for the VHF marine band, but has enough bandwidth to cover the VHF public safety spectrum.

As the weather stays mild and the skies clear, use this time to enhance and upgrade your antenna system.

Our community, Wausau and Marathon County, Wisconsin is in the process of converting their analog radio system over to a narrow band digital radio system. Marathon County has about 130,000 residents and covers an area about the size of the state of Connecticut, so this is no small task. The new system has several microwave links and simulcast transmit and receive sites to effectively cover the area. Unfortunately a slew of technical issues is causing the transition to take longer than necessary and driving up the costs.

But this post isn’t about the technical difficulty of the new radio system, but instead illustrating the fact that when the new system goes on the air, my primary antenna I use for scanning, a KB9VBR J-Pole Scanner antenna will still work with the narrowband digital frequencies. Instead of moving to an 800MHz trunked system, the county is still using their existing VHF frequency allocations. I’ll still be able to use the same antenna and feedline, but I’ll have to upgrade to a P25 digital capable scanner.

Antennas are antennas, regardless if they are receiving an analog or digital signal. So the antenna you buy today to monitor analog frequencies will work tomorrow when they transition to narrow band and digital communication modes. As long as they stay in the same frequency range that the antenna is tuned for, the antenna will still work.

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.

Merry Christmas and Happy Holidays! My antennas make great Christmas gifts and I will drop ship them to any US address.  Wouldn’t you love to see a KB9VBR J-Pole Antenna under your Christmas tree? If you want your antenna shipped as a gift to a friend, just leave  me a note during the checkout process of who and where you want the antenna to go. I’ll even include a nice little card wishing the recipient a Happy Holidays.

Christmas day is Sunday, December 25th. The last day to order one of my antennas for guaranteed Christmas delivery is Wednesday, December 21 by 11:59pm central time.

Thanks again for your support, I greatly appreciate your referrals of my antennas to your friends. Have a most excellent Holiday season this year.

Michael, KB9VBR

A big segment of the scanner community is centered around listening to aircraft communications that happen on the ground and in the air. Living near a major airport, these transmissions can be quite numerous; but even in less populated area you can hear a plethora of signals. Air to ground signals can carry several hundred miles as you listen to planes flying in uncontrolled space. If you are near an airport, FBO, runway, or airstrip, the ground communications can be just as interesting.

My airband J-Pole antennas work great at picking up aviation signals. Most airband listeners tend to gravitate towards discone antennas. While discones work great for scanning because of their broad band nature, they aren’t necessarily the best choice for the aviation band. The Aviation band J-Pole antenna has two distinct advantages over discone and quarter wave antennas.

First the antenna is a half wave by design, so it has more gain than a discone, up to 3db more in most cases. Discones have a spherical radiation pattern, so they pick up signals from all directions equally. The J-Pole’s pattern is more doughnut shape; that is it slightly favors the horizon as compared to the sky. The doughnut shaped pattern works better for aviation as it will give you the advantage of receiving the FBO and ground operations. VHF signals are line of sight, so you’ll have no problem picking up in-flight signals regardless of the antenna style.

The airband J-Pole antennas are custom tuned for the aviation band, so they work equally well for receiving and transmitting a signal. They are usually set to Unicom, but can be tuned to any frequency of your choice at time of order.

Get an airband J-Pole antenna and let your aviation listening soar to new heights.

A frequent question that is asked about my antennas is how much power can they handle. This is a common concern as there are many different styles and construction methods of J-Pole antennas. Depending on what materials are used to build your antenna, its power rating could be vastly different.

The KB9VBR 2 meter J-Pole antenna is constructed out of 1/2 inch Type M copper tubing. Copper is a highly efficient conductor and radiator. The thicker copper tubing, as opposed to copper wire, can also handle a large amount of heat energy. I’ve tested the antenna with transmitter and amplifier feeding it up to 250 watts of power. But there is no reason it could go higher, over 500 watts or more with an antenna carefully tuned to a resonant frequency.

J-Pole antennas built out of wire like 300 Ohm tv twinlead or 450 Ohm ladder line are more limited in their power handling capabilities. I wouldn’t want to put more than 10-20 watts into a twinlead J-Pole for fear that the resistance in the wire will cause it to burn up. 450 Ohm ladder line is made of thicker wire and could handle 50 watts with careful construction methods. Twinlead and ladder line are designed to be a transmission line and not for rf radiation. The wire resistance is low when they are carrying a signal, but once they are put in a situation of radiating a signal, resistance increased. With increased resistance comes heat and the possibility of the insulation, or worse, the wire itself burning up.

If you are looking for an antenna for a VHF base station radio, consider the antenna’s power handling capability and know that you can trust the KB9VBR 2 meter J-Pole antenna to deliver when connected to your high power rig.

My J-Pole antenna brochure has been completely revised and updated. This is the same brochure that is included with every antenna that I ship. In it will you find information about mounting the antenna, tips, and a short history of the J-Pole. You can download the brochure here, or just order an antenna and have one shipped to you .

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KB9VBR UHF J-Pole antenna

GMRS radios are gaining in popularity daily. Inexpensive and effective, these radios are redefining how families keep in touch. Unfortunately you won’t get the range you need unless you have a good antenna. The GMRS J-Pole is similar to the 440MHz antenna, but it is tuned for maximum performance on the 462MHz GMRS band. If your base radio can accept an external antenna (many of the better models can), then adding one of these antennas will greatly improve your range.

Price: $19.00 + 6.50 shipping

GMRS J-Pole Antenna Buy Now

KB9VBR UHF J-Pole antenna

The 2 meter works great on the 70cm band, but sometimes you may want a 440MHz dedicated antenna. This is the one for you. Short, lightweight, and always more gain than a 1/4 wave groundplane; only 30 inches overall with an 11 inch mounting stub.

Price: $19.00 + 6.50 shipping