Do you need an antenna analyzer or an antenna tuner? These devices are actually different tools for different tasks. They both are used with antennas, but one doesn’t necessarily replace the other.
A Box With Many Names
Antenna tuner, coupler, transmatch, matchbox, ATU—all are terms for a device found in many ham stations. This useful accessory lets amateur radio operators help optimize the antenna/transmitter connection and improve the power transfer between them. Tuners can also extend the usable frequency range of antennas on a particular band.
Before we go much further, it’s important that we clear up one misconception: the antenna tuner doesn’t really tune your antenna, or any part of it. And it has absolutely no effect on the SWR between its output and the antenna. But for the sake of convenience, we’ll still call it an antenna tuner since that’s the common name used in the ham community.
In simplest terms, an antenna tuner acts as a kind of adjustable impedance transformer between the radio and the antenna. It takes whatever impedance the antenna system gives it and attempts to convert it to 50 ohms—or something reasonably close—to match the output on the transceiver. When your transceiver sees a 50-ohm impedance, it is able to direct its maximum RF power into the system. The tuner essentially makes your rig think it’s transmitting into a 50-ohm load—even if it’s transmitting into a random wire or a set of bedsprings.
If you use a transmitter on a single frequency or a cluster of frequencies in close proximity on a resonant antenna, you don’t need a tuner. For example, on the 17 meter band, the frequencies cover a small slice of spectrum from 18.068-18.168 MHz. A quarter-wave antenna cut for the middle of the band would work for the entire band.
But consider 80 meters. It covers a whopping 4 MHz of bandwidth from 3.5-4.0 MHz. If you have a dipole resonant at the middle of the band (3.8 MHz), you’ll find that moving up or down the band will make some significant changes in the match between your transmitter and antenna. In this case, an antenna tuner can help you utilize the antenna over a wider portion of the band. Your rig can still see nearly a 50-ohm impedance if you do a little touch-up with the antenna tuner.
Non-resonant antennas also benefit from a tuner. The 31- and 43-foot vertical, longwire, and random wire antennas can all be pressed into single or multiband service with the help of an antenna tuner. Though you can operate the tuner from your station, these antennas work best with a remote tuner connected directly at the antenna feedpoint.
Many newer rigs feature built-in autotuners—something you might want to consider if you are buying a new transceiver. Check the transceiver specs or look for a TUNE button that starts the tuning cycle. Most can handle up to a 3:1 SWR, sufficient for touch-up tuning and minor mismatches. But they won’t handle more serious mismatches—a reason to have a good external antenna tuner as well.
Analyze This
An antenna analyzer is basically a signal generator with a VFO that sends a signal to the attached load and a readout that displays a set of results. Analyzers are generally used by people who are building antennas. It’s a tool that helps you physically tune an antenna and check the entire antenna system.
With an analyzer, YOU are the tuner. The analyzer will help you adjust the antenna dimensions to make an antenna as close to resonance as possible. Analyzers often have graphic displays, making the data easier to understand than a simple meter or digital readout. Some analyzers can quickly produce multiple graphs for multiband antennas and connect to an external computer.
If you have an antenna like a half-wave dipole, you can use an analyzer to adjust it for best SWR for a single or range of frequencies and discover the available bandwidth that falls within the range of 2:1 or less. As long as you stay on that frequency or within a certain bandwidth near that frequency, the transmitter will see something close to 50 ohms. But outside that bandwidth, the SWR readings will climb. Understand that most HF antennas don’t have flat SWR across an entire band, so many pick a favorite frequency or tune for the center of the band.
Many amateur radio operators also use antenna analyzers to troubleshoot antenna-related problems such as diagnosing a break in coax cable or finding faulty antenna components. Sometimes you may have erratic SWR readings and you won’t be able to tune it properly or the tuning will not remain stable. These could be caused by a loose connector or water in the feedline. High SWR readings that occur over time could mean the feedline is starting to fail.
Which is Right for You?
An analyzer is used to set up or troubleshoot an antenna—a good thing to have if you regularly build or experiment with antennas. You’ll use a tuner in day-to-day operations to keep your transmitter happy, thinking it’s transmitting into a 50-ohm load.
In a perfect world with a generous budget, having both would be really great. But let’s review examples of what each one does and match them to your needs.
The following tasks can be done by RigExpert or MFJ Antenna Analyzers:
- Rapid check-out of an antenna
- Tuning an antenna to resonance
- Antenna SWR and impedance measurement and comparison before and after a specific event (rain, hurricane, winter, etc.)
- Making coaxial lines or measuring their parameters
- Cable testing and fault location
- Measuring capacitance or inductance of reactive loads
- Sending data to laptop for larger graphical display and further analysis
- Finding resonance of a trap or coil
Tuners, such as those made by LDG and Palstar, can:
- Compensate for narrow antenna bandwidth
- Help you operate on bands outside of what the antenna was designed for
- Match open wire feedline
- Match random wire or non-resonant antennas
- Provide SWR/reflected power/frequency readings (on some models)
- Provide near 50-ohm match to transceiver
