Garmin

         Garmin was founded in 1989 as one of the earliest companies to exploit the Global-Positioning System as a personal navigation system. In industry as in radar, timing is everything: its systems proved invaluable during the 1990-1991 Gulf War, Operations Desert Shield and Desert Storm, and a niche was created. Today, Garmin provides navigation and communications systems for aviation, marine, automotive and personal use, and has grown into an international corporation. Its presence in the MNR market started in late 2004, since when it has announced a total of six X-band (9410 MHz) products, and plans to introduce a further 4 models in 2010. Information on the radome-based variants is scant:

• There were two generations of radome, each of which has a 2-kW and a 4-kW version. The earlier generation (announced in November 2004), used for the GMR20 and GMR40, comprises a 28"dome and an undisclosed antenna type that achieves a horizontal beamwidth of 3.6°and a vertical beamwidth of 25°. The second generation radome (March 2006), used for the GMR21 and GMR41, comprised a low-profile 24"dome containing a convex patch-array antenna that achieves the same beamwidth as the 28"version. Both antennas rotated at 24 rpm, and the radomes were "all-in-one" systems, with all processing taking place up-mast. No pulse-rate information was published but, given the rapidity of development, it would not be surprising to find that these systems use similar pulse rates to those of the Garmin open-array designs.

• All four of these radome-based designs have been discontinued, replaced by two new 4-kW systems, the GMR18 and the GMR24. The GMR18 comprises an 18" dome with an undisclosed antenna having horizontal and vertical beamwidths of 5.0° and 25° respectively; the GMR24 comprises a 24" dome antenna, with horizontal and vertical beamwidths of 3.5° and 25° respectively. Both systems are capable of rotating at either 24 or 30 rpm. No pulse-rate information is published.
• The GMR404 and GMR406, 4-kW radars announced in July 2006, use a 4' and a 6' antenna respectively, with claimed horizontal beamwidths of 1.8° and 1.1°, and a common vertical beamwidth of 25°. They have two scan rates available, 24 and 48 rpm; unusually, manual change of scan rate is required. The maximum selectable range scale on the radar display is 72 nm, at which range the pulse rate is possibly the lowest published for any MNR; published details of pulse-rate and PD for both systems are as follows:
  

         At least the GMR404 and GMR406 are assumed to be manufactured by Garmin because of their distinctive pulse-rate characteristics.

         Recently, Garmin announced plans for four further models, with 6- and 12-kW peak power outputs, and two antennas for each - a 4' open array and a 6' open array. Information on these new products (GMR 604xHD, GMR 606xHD, GMR 1204xHD and GMR 1206xHD) is scant; however, it seems likely that they will have much the same beam-pattern, pulsing and scan characteristics as the GMR404/GMR406.