When teaching Tech license classes, I always tell the students that the rubber duck antenna that comes standard with a handheld transceiver (HT) is a very convenient crummy antenna. Of course, we really appreciate the compactness of those antennas when using the HT on a day-to-day basis. The problem is that they just don’t perform very well.
The standard rubber duck antenna is basically a shortened ¼-wave vertical antenna. Inside the rubberized cover is a radiating element made out of a wire spring that attempts to make the antenna act like a longer antenna. Shorter antennas will generally be less efficient, which is one disadvantage of the rubber duck. The real problem, though, is that a ¼-wave vertical antenna is supposed to have a ground plane under it. It’s the ground plane that allows the ¼-wave radiating element to perform well, acting like a ½-wave dipole. (You remember all this from your Technician License Class, right? If not, take a look at Chapter 7 of Ham Radio School.com Technician License Course.) Mounted on top of an HT, there’s nothing that really provides the ground plane that we need.
A ½-wave dipole is one type of antenna that does not require a ground plane. Most dipoles are center fed, which means that the transmission line is connected at the center of the dipole. Keep in mind that we want the antenna to be vertically polarized so that means that our dipole should be vertically oriented. Somehow, we’d have to connect the transceiver to the center of this vertical dipole. This setup isn’t going to be very convenient for a handheld radio.
The way to solve this problem is to use a ½-wave radiator but feed it from the end. The MFJ-1714 Long Ranger antenna does just that (Figure 1). The end of a ½-wave is a high impedance point so it is a little tricky to connect the transceiver there. The MJF antenna has a matching network at the base of the antenna that provides the right impedance so the HT can drive the ½- wave element without a problem. Other than that, this antenna acts just like the classic center-fed dipole. Again, because it is a half-wave antenna, it does not need a ground plane.
Fully extended, the antenna is 42 inches long but it collapses down for storage (Figure 2). The MFJ-1714 costs less than $20 and comes with a BNC connector. There is also a version that has an SMA connector on it (MFJ-1714S), which is what most current amateur radio handhelds use. The SMA version is set up for Yaesu, Kenwood, Icom and similar radios. Some of the Chinese radios (including some Wouxun and Baofeng radios) use the opposite gender of SMA so they require an adaptor to use the MFJ-1714S. (For more about SMA connectors on HTs, see this article on my blog.)
I’ve made good use of this antenna and it works great — clearly superior to any rubber duck. A typical use for me is when I am out hiking in the mountains and I either want to hit one of the 2 Meter repeaters or make a simplex contact. Recently, I started using this antenna for Summits On The Air (SOTA) operation. The extra gain from this antenna really helps when out in the backcountry — on both transmit and receive. While there used to be other manufacturers of this type of antenna, currently only MFJ produces one. (If you come across another one, please let me know and I’ll pass it along here.)
Finally, here are a few tips for using this antenna:
- Handle With Care. This antenna is well constructed but it is still easy to bend or break it. Worse yet, the length of this antenna means you could put enough force onto your HT antenna connector to damage your radio.
- This is a single band antenna, so it should not be used on any frequency outside of the 2 Meter band.
- The antenna can be used in the collapsed position and it will work about as well as a rubber duck.
That’s it. Thanks for stopping by Shack Talk.
73, Bob K0NR