Building an antenna is something that you should do within a month or two of getting your license. There are many reasons for this, including:
- Building an antenna will help you learn how antennas really work.
- Building an antenna is cheaper than buying them.
- If you’re using a handheld with the standard “rubber ducky” antenna, you can build an antenna that will increase the range of your handheld.
- It’s fun!
Building a 2m quarter-wave ground-plane antenna
The first antenna that you should consider building is the quarter-wave ground-plane antenna for the 2m band. They are very easy to build and will perform better than the antennas that come with most handhelds.
The quarter-wavelength, ground plane antenna is made up of one vertical element, called the driven element, and four radials. The radials make up the ground plane. An easy way to make this antenna is to use an SO-239 coax connector. The driven element is soldered directly to the center conductor, while the four radials are connected to the four holes in the connector’s flange. See the figure at right.
Now, let’s calculate how long the elements should be. Since the wavelength of a radio wave is equal to 300/f (MHz), one quarter wavelength will be equal to 75/f (MHz). At 146 MHz, therefore, the length of the driven element is:
75/146 = .51 m
In practice, we have to make one more adjustment. Because a radio wave travels more slowly in a wire than it does in free space, the wavelength will actually be about 5% less in a wire than in free space. So, we multiply the wavelength in free space by .95 to get the length of the driven element:
.51m x .95 = .49m = 19.25 inches
The radials should be about 5% longer than the driven element. This isn’t really very critical, so if you make them 20.25 inches long, the antenna will work just fine.
You should make the elements out of a stiff wire. 12 AWG copper wire will work for experimentation purposes. Welding rod might be better for a more permanent antenna.
You need to solder the 19.25-in. driven element to the solder cup of the center conductor of the SO-239 connector. Attach the radials to the holes in the flange of the SO-239 connector with nuts and bolts. You can also use these nuts and bolts to mount the antenna to some kind of bracket. Bend the radials out to a 45-degree angle, connect a coax cable to it, and start having fun!
For more information
For more information on how to build and what you can do with the quarter-wavelength, ground-plane antenna:
- Capital City Amateur Radio Club SO-239 antenna
- Simple 2 Meter Ground Plane Antenna Project with PVC Support
Benjamin KC9UNS says
2 weeks after I got my ham ticket I built a ground plane antenna, its a little bit easier than building a J pole due to finding latter line. Most hardware stores don’t carry it anymore.
a ground plane only consists of a SO-239 found at Fry’s and some Shacks and wire from a coat hangers or the stuff used in wiring houses.
Casey TI2/NA7U says
I suppose this is the way of things nowadays, 2 meters is the first thing new hams go for (?). I was always interested first and foremost in HF DX. Even easier to build an antenna for that, the venerable dipole!
73!
Fred KM4QLB says
Casey wrote: “I suppose this is the way of things nowadays, 2 meters is the first thing new hams go for (?). I was always interested first and foremost in HF DX.”
Many hams go for 2 meter because it’s so versatile, inexpensive, and because 2 meter FM offers superior audio quality while being less susceptible to RFI. You can hit a local repeater with a 2 meter handheld, letting you talk over a large metro region. If you live in an apartment or condo, a 2 meter antenna is easy to set up and unlikely to incur the wrath of your neighbors. If you want to go mobile, you can have a small, discreet antenna on your vehicle.
Nothing wrong with HF DX if that’s what you’re interested in, but there’s also nothing wrong with using a 2 meter handheld, mobile, or base to talk with local hams, set up get-togethers, communicate while camping, etc.
Dan KB6NU says
Benjamin: I think you’re right about the ground plane. I may have to rewrite this chapter and give instruction on how to do that.
Casey: I’m an HF guy, too, but yes, more people now get on VHF first, I think.
Benjamin KC9UNS says
Casey: You are right most new hams do tend to go towards the 2m and 70cm, I think due to the price of the rigs and the availability.
Roger KE0FGJ says
For me its the cost of the HF Transceiver and I like to build antennas. The antennas are smaller at VHF/ UHF, and will fit on my small lot.
James Stamper says
HF rigs are way more expensive. For a Technician who only has a small slice of the 10 meter band for voice mode, and SSB at that, the cost is over $300 just for the radio. Still a worthy goal but when you consider a 2m HT like the UV-5R can be had for less than 1/10th that amount, its easy to see why 2m is the way to go for new hams. With the local repeater I can cover a large portions of at least 7 surrounding counties. Its not DX but I have less than $50 in the entire system including radio, coax and antenna!
Dan KB6NU says
You’re right. Baofengs are an inexpensive way to get into the hobby. If that’s the only radio that you have, though, you’re really limiting yourself. Spend a little more (and upgrade to General) and you’ll have a lot more fun in ham radio.
homer says
Dan, Why do you say that
Dan KB6NU says
There’s only so much that you can do with an HT (of any brand, not just Baofengs). If you invest in gear that will do more, you’ll have more fun with ham radio.