MP Antenna’s Super-M Classic Mobile HAM Radio antenna featured in the QST Magazine Short Takes
Last April I reviewed the MP Antenna Super-M Classic base antenna in this column. This unusual-looking antenna is designed to cover 25 to 1300 MHz with low SWR on the 144, 222 and 440 MHz amateur bands. With its tilted elements it creates a radiation pattern that is somewhat crossed polarized between horizontal and vertical, giving you some of the best of both worlds, so to speak. At the time I wondered if the same arrangement might be effective in a mobile environment, especially as a means to reduce mobile “flutter.” Well …
If you don’t mind attracting stares with your vehicle, there is a mobile version of the Super-M Classic antenna to consider. The radiating portion of the antenna is virtually identical to the Super-M Classic base. There are three stainless steel elements ranging from 15 to 20 inches in length and all are tilted about 30 degrees from vertical. As with the base version, the Super-M mobile boasts a receive frequency range spanning 25 to 1300 MHz (good for mobile scanners) with low SWR segments at 144, 222 and 440 MHz for transmitting.
The difference between the designs begins at the base of the antenna. The Super-M Classic mobile is designed to fit a standard NMO antenna mount. For the purpose of this review, I purchased a Larsen NMO magnetic mount. Assembling the Super-M was straightforward and took all of 10 minutes. You simply secure the Super-M radiating elements with the Allen wrench provided and then screw the base onto the NMO mount.
On the Road
The Larsen mount instantly grabbed the roof of my SUV with a mighty thump. I snaked the RG-58 coaxial cable to my antenna analyzer and began taking measurements. The SWR on 2 meters bottomed out at 2:1. It dropped to 1.5:1 and 1.6:1 on 222 and 440 MHz respectively.
While a 2:1 SWR on 2 meters may seem high, keep in mind that the cable was only about 12 feet in length, so the loss due to SWR (about 0.7 dB) was well within acceptable limits. Even so, I disconnected my trusty dual-band mobile antenna, which is secured to the vehicle with a trunk lid mount, and substituted the Super-M to test whether a better ground would improve the result. Sure enough, the 2 meter SWR dropped all the way to 1.2:1.
With the Super-M back on the magnetic mount, I connected a multiband transceiver and took to the highway. Despite the porcupine element design, the Super-M had no problem sticking with the Larsen mount, even at 65 MPH. With my daughter’s assistance, we switched between the Super-M and my dual-band vertical while checking for signal reports on a distant 2 meter repeater. According to the reports, the Super-M appeared to have a definite advantage when it came to reduced mobile flutter. In one instance, the flutter disappeared completely when we switched from the dual-band vertical to the Super-M. Signal reports on simplex were similar with the Super-M occasionally coming out the winner when it came to overall strength.
Since the ARISSat-1 satellite was predicted to put in an appearance during our test, I packed a laptop computer and used it to capture a Slow Scan TV image from the bird on 2 meters with the Super-M while racing down Interstate 91. You can see the result in Figure 1. Noise and fading effects are present in the image, but it isn’t bad considering the fact that we were receiving a weak FM signal from a couple of hundred miles away.
Odd Appearance, Good Performance
I was quite pleased with the Super-M Classic mobile antenna. Yes, it certainly drew some curious glances, but so do many ham antennas. Its performance rivaled, and often bested, my dual-band mobile vertical, especially in terms of reducing annoying flutter.
MP Antenna, LTD. (http://www.mpantenna.com) is the exclusive developer and manufacturer of advanced Multi-Polarized antennas that are well-suited for a range of applications including public safety, wireless broadband systems, WiFi, WiMax, video monitoring systems, 3G, CDMA, GSM, PCS and LTE. The company’s product line improves signal penetration and connectivity in obstructed deployments providing increased data throughput, enhanced voice clarity and multi-path mitigation. MP Antenna’s products are protected under numerous US patents with many US and foreign patents pending. MP Antenna is privately held and designs and manufactures its products at their headquarters located near Cleveland, Ohio, USA.