Antennas

Before we begin...don't believe some other sites that say <10 watts won't hurt.
I believed that and learned the hard way.
Always double-check the TX is off (and disable automatic controls!) before making adjustments.

Measurement Tools

WORKMAN Analog VHF-UHF SWR Meter

Reviews, Specifications, etc. are available on eHam.net

To start out, I got a simple analog VHF-UHF SWR meter. It's not great but it certainly does the job. For UHF work, this is still the only tool I have.

RigExpert AA-170 Antenna Analyzer

Reviews, Specifications, etc. are available on eHam.net
The manufacturer's page for this model is also available here.

For HF and VHF (up to 170MHz) I now have a RigExpert AA-170 antenna analyzer. This was brought to my attention when I was at Ham Radio Outlet inquiring about a MFJ antenna analyzer. After speaking to the salesmen and examining both the MFJ unit I was originally interested in as well as this RigExpert including reading thru the manuals I ultimately decided to go with the RigExpert unit since it was similar cost and at the time I didn't think I would really use anything over 2 meter frequencies much. In some ways I regret not getting something which could do 70cm frequencies but the equivelant unit that can do UHF frequencies is considerably more expensive, more so than I am willing to spend for the amount I find I want it.

One nifty feature this has is the ability to connect to a computer and perform analysis generating graphs of the SWR over a specified range of frequencies, with a specified number of sample-points resolution. I also discovered an unexpected use, while helping tune a fellow ham's antenna I was able to set up the analyzer with my laptop in his shack and then remote-control my laptop over WiFi remote-desktop to perform the tests. This saved the headache of running back and forth between the antenna mast and the shack to take readings which made the job much easier.

You'll see some of the screenshots and computer graphs generated by this throughout this page on any antennas I discuss which operate within it's frequency coverage.

My Home-Built Antennas

Roll-up ladder-line J-Pole

Design plans available at hamuniverse.com

This was the first antenna I attempted to build after getting licensed. It was a bit of a challenge, especially soldering the coax without melting the dielectric foam but it's still the best antenna I have by leaps and bounds peformance-wise.

For reasons I can't explain, it performs vastly better at a slight angle and the SWR drops really nice and low at this angle as well. I'm guessing there's something behind the wall but in any event I'm extremely happy with the performance and use this as my main antenna at my "hobby table". It's held to the wall by a couple screw-eyes and uses string and zipties to insulate the antenna from the metal hooks holding it up. There's maybe 3-4 turns in the choke, less than perscribed in the plans but I didn't leave enough coax so I had to improvise.

2 meter band SWR graph

Quarter-Wave Ground Plane (2m and 70cm)

I don't have any pictures of these -- both met their demise being crushed either in transport or storage. One of the biggest pitfalls of these antennas is they are very fragile being made of easily-bendable copper wire and taking up a relatively large amount of space. After straightening the wires so many times I eventually moved on to other better antenna designs that seem to be better form-factor.

So why is this here then if it has so many issues? Quite frankly, this seems to be the easiest to make, most fool-proof, and inexpensive antenna I've seen yet. It can be assembled in about 5 minutes with the most basic of tools and, if the wire is cut properly, almost always has better than 1.2:1 SWR the first try without any hassle of ground-planes or positioning coax.

At 70cm frequencies this antenna becomes "usable" size for an indoor antenna, and I suspect at higher frequencies it would work even better still, being that it gets stronger and less prone to damage as the element and radils get shorter.

Construction:
Look at this for a diagram of approximately what you are building. They have sample measurements for 2 meter band or you can compute them with another link I provide in the steps below. Also, wear safety goggles because this has lots of places where you can poke an eye out if you aren't paying attention to where the wire is flipping around.

Purchase a SO-239 panel-mount jack
Locate 4x screws with matching nuts, 6-32x1/2 works best in my experience
Compute the length of wire you need using a calculator like this one. You will need 4x the "radial length" and 1x the "vertical length" + an extra 1ft (because the most expensive useless wire is "almost" long enough). I recommend #14AWG solid-core single-strand wire, which is very inexpensive "by the foot" at most hardware stores.
Begin by stripping the insulation off the wire completely - I do this by holding a utility knife against at a slight angle against the wire on a solid table. When you get the angle "just right" it will effortlessly slide thru slicing an edge off the insulation. When this is complete, you can then peel the remaining "C" shape insulation off like peeling a bananna.
Now begin construction by cutting a length of wire for the element according to your previously calculated measurements. A bit long is okay but not too short. Solder this to the center pin of the SO-239 connector. Now, measure from the BASE of the SO-239 to the top of the soldered wire (including the length of the "stub" on the connector which you soldered to) and trim it to the correct length according to the measurements. If desired, sand the tip of the wire so it's less sharp.
Next, we will work on the radials. Take the spool of new wire and form a circle about 1/8" inside-diameter in the end, solder it into a closed loop. This is what the screw will go thru to secure it. If you have a large blob of solder, it is helpful to file it flat so it's about the same thickness as the loop in the wire.
Measuring from the closed part of the loop, cut a length of wire according to the "element" measurement you calculated earlier and cut the wire.
Now, put a screw thru the SO-239 with the screw-head on the side where the coax will attach. Thread the loop in the radial over the pertruding screw and secure it with a nut at the top. Ideally you want it pointing outward so if you draw an imaginary line from the element (in the center of the connector) to the screw you just put in, the radial will follow along in a straight path.
Repeat this for the remaining 3 radials
Now, complete the antenna by bending each of the 4 radials downward at a 45-degree angle. If you are OCD you can use the pythagorean theorum and a bit of geometry to compute the expected distance between all of the radials at their farthest point but I've found it's usually enough to eye-ball it and then do a rough measurement that they are all evenly spaced. Optionally, you can use some light-weight plastic or other non-conductive material to help re-enforce the radials and ensure they stay in the proper position for optimal antenna match. I did this with a piece of plexiglass on my 70cm antenna and it worked really well while it lasted.
To support the anntenna, I find it's useful to find a piece of PVC pipe that the coax can pass thru and then clamp it to something like a camera tripod. The weight of the coax dangling will hold the antenna securely at the top of the PVC pipe.
If this will be within reach of *anyone* (e.g. indoors) I also suggest putting a flag of bright-colored tape (such as colored duck-tape) on the tips of the radials and element, they are very hard to see and would be a risk of poking someone's eye out.

That's it! Now you should have a finished antenna ready to use.

Slim-Jim in PVC pipe

Starting design plans available at hamuniverse.com

This antenna was suggested to me by a local ham, Larry AK4FB, shortly after I got on the air. It seems to perform fairly well in spite of being installed in a sub-optimal location (very close to a metal corner on my drywall next to an aluminum window). The SWR is a bit high but that's a result of the location it's in, I recall it being much better when I was constructing it in the middle of my bedroom.

For the construction, I found a piece of PVC pipe to meet the description in the plans (either 1/2" or 3/4" ?) for spacing, then ANOTHER piece of bigger (1") PVC that fit over that with a big enough gap for #14AWG wire inbetween them. I constructed the antenna per the plans on the smaller piece of pipe and used one wrap of electrical tape every foot or so to hold the wire in place. After I got it assembled, I slid the whole thing in the outer pipe and tuned it. This involved LOTS of putting it together and taking it apart but eventually I got a reasonable tuning. At that point I cut a notch in the outer PVC pipe to fit around the SO-239 connector and (being careful not to drill into the wire) put screws in a couple places to hold the inner and outer pipes together for structural re-enforcement. Once it was tested I then applied large amounts of liquid electrical tape at the point where the outer pipe pieces met the SO-239 connector. The mounting brackets are simple circles with a tab extending that I made on my 3D printer.

This seems to work acceptably, even though the SWR in the location it's installed is higher than I would have liked. On the plus side, it's almost completely invisible inside and out because it's in the edge of the window frame, covered by the curtains.

2 meter band SWR graph

300 Ohm Twin-Lead J-Pole in PVC pipe

I don't have a link to specific design plans for this antenna, in fact I can't 100% remember if it was a J-pole or Slim-Jim style antenna. Essentially I constructed a standard 300-ohm twin-lead roll up antenna and slid it into a piece of PVC pipe, with the main difference being where coax is normally connected I installed a SO-239 connector. The intent was to build a ligher-weight antenna equivelant to the Slim-Jim in my window but it didn't work out exactly the way I wanted. Ultimately this ended up being allocated to my Pro-651 radio scanner (which I can remote-control over the internet with the Win500 software application) to improve it's received coverage. While it doesn't do as well as I hoped for amateur radio, it nearly trippled the VHF range I can receive on my scanner over a generic VHF-UHF telescoping antenna.

2 meter band SWR graph

70cm J-Pole style on SO-239

Design plans available at KN9B's site.

I constructed this antenna for my Echolink node which operates primarialy on the 70cm band. I needed something more durable and more easily packed for travel and found these plans while hunting for a 70cm J-pole antenna. It's fairly straightforward and seems to work well, after tweaking the antenna and playing with putting a loop in the coax at various points I was able to achieve a SWR of 1.4:1 on 446.1 MHz. While not as good as the quarter-wave ground-plane, this I think this is quite acceptable for my needs considering how much more compact it is.

I followed the directions almost to the letter with only a couple minor substitutions. I was unable to locate the copper-clad rod so I used 1/8" brass rod from the hardware store as the radiating element, and I 3D printed the spacers for the matching stub using black ABS.

The hardest part of the whole project was getting the matching stub attached to the screw so it stayed straight. I finally ended up grinding a notch in the screw and a ring around the rod, then wrapping #30AWG wire to hold it in place while I soldered it together. Once that was complete it was fairly easy to finish assembly of the rest and trim it until I found the best SWR. I think if I had different spacing in the matching stub or different diameter rods it may have worked better but I haven't attempted to make any additional modifications since it's doing quite well the way it is.

HF Slinkey Dipole

For HF in my apartment, I have a "slinky dipole" that is resonant on 40 meters and also happens to be fairly good on 15 meters. It wasn't designed with anything special, just stretching the slinkys across the cieling adjusting the length of nylon string at the ends until it read good on my analyzer. Unfortuniately due to the high noise floor (S7-S9+) in the surrounding apartments I can't use it much, though I have made a couple JT65 contacts to other states on 40m using this antenna.

5-band SWR test (RigExpert AA-170 screenshot)

40 meter band SWR graph

15 meter band SWR graph

2-Meter Tapemeasure Yagi

Design plans available at WB2HOL's site.

This is an antenna I'd been wanting to build for quite some time. It's designed for radio direction finding but if it's tuned well could also be used for transmitting. Mine didn't come out as well as I hoped (around 1.5:1 to 2:1 depending on orientation) but it's "good enough" considering I built it in about 2 hours in one afternoon and likely will use it for RX only. Total cost for parts was under $20 at Lowe's for the PVC pipe, fittings, hose-washers, camps, and tapemeasure. I already had some wire for the matching stub.

2 meter band SWR graph

Flagpole Hamstick Mount

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