Yaesu ATAS-120A
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| Frequency | 7 MHz, 14 MHz, 21 MHz, 28 MHz, 50 MHz, 144 MHz, 430 MHz |
| Bands | 40m, 20m, 15m, 10m, 6m, 2m, 70cm |
| Modes | SSB, CW, AM, FM, digital |
| Connector | PL-259 (UHF male) base, NOT SO-239 |
| Year | 2005 |
| feedpoint | PL-259 (Type M male) base. Mounts on SO-239 mobile mount. |
Yaesu's motorized active-tuning antenna: press TUNE on a compatible Yaesu radio and it sweeps to resonance automatically, covering HF through UHF in one antenna. No manual band changes are needed, and the tuning signal travels over the coax (no separate control cable). It works with modern Yaesu radios (FT-891, FT-991A, FT-710, FTDX-10) and older models, and with non-Yaesu radios via the MFJ-1925 controller.
Only 120W (low for HF). It is a compromise on every band (4.6-5.2 ft on 40m is very short). It does not cover 30m, 17m, or 12m. VHF/UHF coverage may need the ATBK-100 counterpoise kit. Avoid magnetic mounts (insufficient ground for the motor). $350-400 is premium for a compromise antenna.
An automatic HF/VHF/UHF mobile antenna for Yaesu radios. Change bands on the radio and the antenna tunes itself. The trade-offs are power (120W) and per-band performance versus dedicated antennas.
The Yaesu ATAS-120A is a motorized auto-tuning mobile antenna, a 'screwdriver-style' whip that retunes itself electrically as you change bands or frequency. It covers an unusually wide span for a single mobile antenna: the 40, 20, 15, 10, and 6-meter HF bands plus 2 meters and 70 centimeters. A small motor inside, commanded by voltages sent up the coax from a compatible Yaesu radio, adjusts the antenna's effective length to find the lowest SWR automatically.
That automatic tuning is the whole appeal: with a supported Yaesu transceiver you press tune and the antenna sorts itself out, no manual coil-tapping or stopping to swap resonators. It is a compromise antenna in the physical sense (a short, loaded whip on HF will never match a full-size antenna) and it depends on a good ground or counterpoise (the vehicle body) to work well. Power handling is modest at about 120 watts, in keeping with its mobile mission.
It is a current product tied to Yaesu's radio ecosystem. For a manual motorized alternative, the Tarheel screwdriver antennas cover similar ground with more power, and a simple Hamstick is the cheap single-band option.