|Discontinued Shortwave Antennas|
The RF Systems MT (also called the MTA) is a nonamplified vertical receiving antenna covering 500 kHz to 30 MHz. This antenna is designed for listeners who wish to monitor longwave, medium wave and shortwave, but do not have a large space for antenna. Unlike active antennas, the MT uses passive magnetic transfer technology to deliver a good signal with low noise and complete immunity to receiver overload from nearby transmitters. The MT antenna employs a helical form that ensure that the antenna is omni-directional receive pattern. The helical has been constructed in such a way that the polarization is elliptical. It is a mixture of 90% vertical and 10% horizontal. These reduces the problem of polarization fading.
The MT (magnetic transfer) receiving antenna is one of the few (if not the only) 7 foot antenna which is broadband in performance, yet does not require an antenna tuner. It does not need radials, nor does it suffer from intermodulation products. The signal level will be less that that achieved by using full-size active antennas. However, the earthed antenna element together with the Magnetic Transfer technology ensures a lower background noise level and most communications receivers offer enough sensitivity to compensate.
The MT antenna consists of a weather-proof plastic pipe, 1.5 inches (32 mm) in diameter and 7 feet (2.1 meters) long. The internal components of the antenna are filled with ply-urethane foam, thereby making the antenna fully waterproof. The connector (SO-239) in the metal base is sealed with an artificial resin which stops any moisture entering the antenna. The antenna offers little wind-resistance, and the properties of the plastic ensure that the MT, GMDSS and GMDSS-2 are sturdy enough to withstand near hurricane force conditions.
The RF Systems GMDSS is designed in a similar fashion to the MT, but has different frequency coverage. The GMDSS receives 100 kHz to 25 MHz. This version is optimized for Global Marine Distress & Safety System frequencies including the long wave NAVTEX frequencies. This antenna is the same physical size as the MTA. Click here to view a GMDSS/MTA comparison chart.
The RF Systems GMDSS-2 is designed in a similar fashion to the MT and GMDSS, but has different frequency coverage and is shorter. The GMDSS-2 receives 500 kHz to 18 MHz. Its is suggested for those who do not want such a tall antennas as the GMDSS or MT. (Reception of 100-500 kHz is possible with reduced performance). The GMDSS-2 is only 4.1 feet (1.25 meters) high. This model is discontinued.
Please note that all of the antennas above are for receive-only (not transmit).
The optional AK-2 Mounting Kit provided for the easy attachment of either the MT, GMDSS or GMDSS-2 to a vertical or horizontal pole. This kit consists of a special bracket and 4 "U" bolts. Two "U" bolts attach to your mast or pole, and the other two "U" bolts attach to the bottom portion of the antenna.
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