Welcome to the Cuyahoga Falls Amateur Radio Club

The Third Annual Ohio 2 Meter FM Simplex Squares Contest

Improving Your Antenna

Probably the single biggest thing you can make to increase the number of contacts is to improve your antenna, especially if you're using the 'rubber ducky' that came with your handy talkie. Depending on your mechanical skills, there are a number of simple and inexpensive steps you can take to improve your signal.

As you start to investigate antennas, you will encounter the term decibel, abbreviated db, when antennas are compared. For a quick explanation of the term, see the last three paragraphs in this page.

Read this if you're planning on using a rubber ducky:

For 2 Meter operation, the simplest full sized antenna, a half wave dipole, should be about 38.5 inches in total length; with the signal feed point in the center. If you consider the antenna connector on your HT to be the center feed point of the antenna, when you are using a 'rubber ducky' two problems should be obvious. The top half of the antenna nowhere near its optimal quarter wave length of 19.25 inches, and there is no bottom half of the antenna at all! A typical 'rubber ducky' antenna has about -5dbd gain, which means that compared to a half wave dipole, your rubber ducky is only about one third as efficient. Two thirds of the signal, both going in (receive) and coming out (transmit) of your HT is lost. So how do you improve things? Either improve your HT antenna, or use a separate antenna. If you want to see a decisive comparison between a rubber ducky and a home made quarter wave ground plane antenna, check out this YouTube video starting about 10:55 minutes: https://www.youtube.com/watch?v=HkmD3Sgz7Q0

You will get better results using an external antenna, but if you decide to use an antenna directly attached to your HT, the longer it is, up to about 19 inches (a quarter wavelength at 2 meters) the better it will work. You can buy longer 'rubber ducky' antennas (than the one that came with your HT), but the longest I've seen is a type of antenna called a piano wire antenna. It is relatively inexpensive (about $20 at hamfests) and flexible enough to not strain the antenna connector in your HT. A piano wire antenna provides a significant signal improvement over the typical 7 or 8 inch 'rubber ducky' that came with your HT.

Top two antennas are piano wire style, and have better gain than the 'rubber ducky' style antennas that come with HTs.

You can improve this configuration even more by adding the other half of the antenna. An HT uses both its case and the body of the operator (which is capacitively coupled to the case when you're holding it) as the other half of the antenna. Nothing personal, but your body doesn't make a particularly good antenna.

What you can do, is take a 21 inch piece of insulated wire, strip about two inches of insulation off one end, and wrap it around the shield part of your antenna connector, so that it makes good electrical connection. Let it hang down below the body of your HT when you use it. You want to end up with about 19 inches of wire hanging off below the antenna connector. Length is not critical. In tests using a communications service monitor at an ARES meeting about two years ago, this simple trick provided between 1.5 and 2 db of gain compared to not doing it. Either of these steps will help, but by combining a piano wire antenna and this 19 inch counterpoise, you can significantly increase both the effective transmit power and the receive sensitivity of your HT.

Close up of an HT with a piano wire
antenna and a 19 inch counterpoise wire.
Close up of the attachment of the 19 inch counterpoise wire.

Better Antennas . . .

However, a better approach is to use a separate antenna. Whatever radio you are using, you can build an inexpensive antenna that will out perform an HT antenna. When it comes to antennas, there are many ways to categorize them, and radiation pattern is one of them. For a uniform horizontal pattern (not to be confused with polarization) choose an omni-directional antenna such as a half wave vertical dipole, a half wave ground plane, or a J-pole or slim-jim style antenna. If you want a directional sensitivity, you can build a beam or a quad, both of which will be are relatively small and light weight at 2 meters. Keep in mind, you're not getting something for nothing here; with a directional antenna such as a beam or a quad, the gain you get in one direction is offset by the lack of gain (or signal loss) in another direction. And that's not necessarily a bad thing; sometimes you can aim the insensitive direction of the antenna at a source of interference to minimize it, while contacting the desired station using the high gain side.

A note to mobile contesters: If you have a quarter wave magnetic mount antenna on your vehicle, you already have a very efficient half wave center fed antenna dipole. You probably wouldn't see much improvement with any of the omnidirectional antennas here, so if you want to improve on that, try a directional antenna and see how that works compared to your "mag mount".

If you are new to antenna building, I urge you to contact someone in your local ham club who has antenna building experience. Most antennas can stand some minor tuning, because dimensions in the plans may not be exact for the components that you are using. Someone who builds antennas often has or has access to an antenna analyzer, such as the MFJ-259, or a vector network analyzer, either of which can help you optimize the performance of your antenna.


With that in mind, here are plans for a number of simple and inexpensive antenna projects any of which you can build. Search the net for more antenna construction plans and YouTube for construction tutorials. <.p>

A 2 meter half wave center fed coax dipole. This antenna is omnidirectional and has 0 dbd gain - because it is a dipole. The advantage is it's simple to make, will probably slightly outperform a piano wire/counterpoise HT antenna. Because you build it at the end of a PVC pipe, you can use more PVC to get it up in the air, perhaps as much as 10 feet. At 2 meters, elevation helps increase distance contacts. It's somewhat unique because it initially appears to be an end fed vertical dipole, but it is not. The feed point is where the center emerges from the shield and continues upwards unshielded. From the feed point down to the required decoupling coil of coax, the shield serves double duty, it acts as the lower quarter wave radiator, and as the shield on the coax that delivers the signal to the feed point. Beyond the decoupling coil, the shield only serves as the shield part of the feed line.

A good web site that describes the construction of this 'Half Wave Flower Pot Antenna' (as they call it) and has lots of photos and clear instructions has one draw back, their measurements are in millimeters (mm). But it's easy to convert mm to inches (multiply mm by .03937 to get inches) so that should not a big issue. This site also describes the steps needed to build a cocky shield. Luckily in the states, we don't have White Cockatoos attacking our antenna feed lines (at least not in Northeastern Ohio). The site can be found at: http://vk2zoi.com/articles/half-wave-flower-pot

A 2 meter J-pole. The J-pole antenna is a family of end fed antennas that some hams swear by and some swear at. Tuning them to the desired frequency can be touchy, and being end fed, the coax feed line must be decoupled from the antenna by a choke balun. Adding ferrite filters to the choke balun is even a better idea. A close variation, which is said to have lower angle take off lobes (a good thing) is the slim-jim antenna. J-poles can be made from 300 ohm twin lead, 450 ohm window line, and even copper pipe. Here are a few web sites offering J-pole construction articles for each of these materials:

Using 300 ohm television twin lead:

Using 450 ohm ladder line:

Using copper pipe (these can be suitable for long term installation outdoors):

Lastly, here's a site with plans for all three:

A 2 meter quarter wave ground plane. This is an open air variant of the magnetic mount ground plane. The vertical radiator is a quarter wave long, and the four ground radials form a "mirror" of that radiator, the same way a conductive vehicle roof does for a mag mount, to make up the other quarter wave. It's made from an SO-239 coax connector and the elements can be copper wire, brass rod, and I've even seen them made with wire coat hangers. A bit of soldering is needed, as well as a couple of machine screws and nuts. It's light enough to hoist up into the air on a piece of PVC, but be careful and make sure you bend a small loop in the end of each of the 5 elements, to keep from poking yourself with it.

Here's a YouTube video that shows how to build one:

Here's a web site that contains instructions for building two quarter wave ground planes and phasing them to create a directional antenna with 6 dbd gain!

A 2 meter 3 element tape measure beam. This is a very popular directional antenna that uses PVC fittings and a cut up spring steel tape measure for its elements. It provides about 7.3 dbd gain (almost 6 times your transmit power and receive sensitivity in the forwards direction) and has a very deep null (over -40 dbd (negative gain relative to a dipole)) off the backside, also making it very useful for radio direction finding. The elements can be folded up for transport and the whole thing weighs less than a pound. Like any antenna, there are some trade offs, it does not do well in a strong breeze, the tape measure elements easily get blown out of position.

Directional antennas rely on the presence of one or more 'parasitic' elements near the driven element. These 'parasitic' elements are electrically conductive and even though not connected to anything else, their presence distorts the normal donut shape of the radiated field of the driven element. The lengths and positions of the elements with respect to each other give the antenna its characteristic gain pattern. This also means that other conductors near and around an antenna can detune and distort the pattern of it. You should use PVC or a similar non-conductive pipe for a mast, and make sure the coax runs along the boom and only drops down to the radio several inches after passing the reflector element.

After building a few, I have some advice for you if you choose to build one. First, be very careful, the cut ends of a spring steel tape measure can be razor sharp!! As soon as you cut it, protect sharp ends, with electrical tape, or hot glue, or liquid plastic (tool dip) insulation or some other technique. I lost blood both times I build one, and I'd rather leave it at the Red Cross. Secondly, you can avoid using hose clamps by just centering the reflector and director elements (rear and front) through the PVC, four way fittings and then marking them where they meet the PVC sleeve, using pop rivets (or machine screws and nuts) to attach the coax, hairpin loop, and elements to the PVC fitting. I also wrapped 7 or 8 turns of coax along the boom (and then taped it in place) to decouple the coax shield from the element (a type of balun). Lastly, I duct taped a scrapped out hair dryer handle to the boom to help hold it. You could also glue a PVC Tee fitting behind the reflector and add a small piece of PVC for a handle. Two of these suggestions are shown in the picture below.

Details of the tape measure beam, showing the coax decoupling balun and the centering marks on the reflector element.

The designer's web site does an excellent job describing its operation and how to build one, and can be found at:

A 2 meter 3 element quad. Quad antennas are directional antennas and can be thought of as beams whose elements are full wave in length and have been bent into squares. Similar to the tape measure beam discussed above, the suggested quad consists of 3 elements, a reflector, a driven element, and a director element. The 3 square elements form a cubic rectangle about 32 inches long and 20 inches on a side, about the dimensions of a medium large have-a-heart live animal trap. Again, use a PVC support mast and carefully follow the directions for attaching the coax and directing it away from the elements of the antenna to avoid affecting the radiation pattern.

The following web site provides the dimensions and construction information for building a 2 meter 3 element quad antenna, but does not have as many detailed photos and descriptions of the construction as was in the half wave dipole article above.

Here is a 40 minute YouTube video by Dave, KG0ZZ that goes into great fabrication detail while building a 3 element cubical quad antenna.

Beam or Quad?

When it comes to directional antennas, perhaps you're asking which antenna to build? A long held belief is that because the square of a quad was formed from a full wave length conductor as opposed to the elements of a beam being about a half a wavelength long, that it would have more gain than a beam with the same number of elements. If it does, it appears to be less than 1 db gain, essentially negligible. There have been long and heated debates, almost bordering on religious wars, as to which style of directional antenna is 'best'. The fact that both sides have strong supporters suggests that both styles perform approximately the same, and you probably won't hear much difference between the two.

More Antennas

There are many more antenna designs that will work well for 2 meters. You are encouraged to do some online research and find and build the antenna that you think will work best for you. Some more 2 meter antennas (along with other VHF band antennas) can be found at: http://www.iw5edi.com/ham-radio/?vhf-antennas,7

Connecting the antenna to my radio:

One thing hams quickly learn is that there are several different types of RF connectors used in ham radio. The three most common ones (from large to small) are UHF, BNC, and SMA. Most mobile and base radios will have a UHF connector while HTs have either BNC or SMA. The following photo shows the two common HT connectors:

Close up of two popular HT antenna connector styles (SMA male on left, BNC female on right)

Most of the antennas that I have built have used of coax cable with preinstalled BNC connectors on them. These can be purchased online in the form of BNC jumpers for a few dollars each and by cutting one end off you get a nice piece of coax with a connector already installed. If you don't need a long cable, you can cut a jumper in the middle and get two pieces of coax with BNC connectors pre-installed.

However, if your radio doesn't use the same connector style as on the end of your coax, the solution is to buy an adapter. They're about $4 each, commonly found at hamfests, and all variations are common. You will need to know the gender and the style, such as "male SMA to female BNC" or "male UHF to BNC Female" (male UHF also known as PL-259). The photo below shows some common adapters.

Close up of five common RF adapters

About Decibels ...

Lastly, a couple of paragraphs about the intimidating decibel, abbreviated db. When antennas (among other things) are compared, a measurement unit called a decibel (a tenth of a "bel") is commonly used. In fact, whenever you hear the term decibel, think "comparison". A decibel is a logarithmic unit that is used to compare one power or intensity level to another. When used to describe the gain of an antenna, the gain of that antenna is being compared to the gain of a known reference, usually another antenna. What reference antenna? It depends on what form of db term is used.

Imagine a point in space, with nothing around it, that is radiating a signal uniformly in all directions with equal power. This is an imaginary antenna because it can not be made as a physical reality. It is called an isotropic radiator and while physically impossible, it is a useful reference tool to compare real antennas to. When it is used as a reference for another antenna, you will see the term dbi used. It means 'decibels, relative to an isotropic antenna'. The simplest antenna that can be physically made is a center fed half wave dipole. This antenna radiates energy in a donut pattern (as opposed to a spherical pattern for the theoretical isotropic antenna) and so it is considered to have gain in the direction of the donut, about 2.15 db over an isotropic antenna. When a dipole is used as a reference, the term dbd is used. Consequently, a dipole is said to have 2.15 dbi. Another commonly used decibel reference that you may encounter (though not much with antennas) is abbreviated as dbm, meaning 'decibels relative to 1 milliwatt (in a 50 ohm system').

Each 3 db increase in gain has the equivalent effect of doubling your transmit power and listening sensitivity. In other words, if you are transmitting with 25 watts into an antenna with 3 dbd gain, it would be the equivalent of transmitting with 50 watts (twice the power) into a half wave center fed dipole antenna. Thus, a 3 db gain doubles your effective power, a 6 db gain quadruples (doubles and then doubles again) your effective power, and a 9 db gain multiplies your power by a factor of 8 (two times two times two). Ten db of gain is about a 10 times increase in your effective radiated power. A 5 watt HT connected to an antenna with 10 dbd of gain would perform similarly to a dipole driven by a 50 watt amplifier. A nice dbm reference sheet (in PDF format) can be found at: http://www.minicircuits.com/pages/pdfs/dg03-110.pdf