There are many choices in radar antennas, in genral for most boats a dome providing up to 24 Nm will do for the bay. they tend to be less expensive and esy to install
Some info on antennas from Furuno, Raymarine, JRC, etc have similiar info.
Regarding Radar Antennas:
As with any Radio Frequency (R.F.) device, the performance is only as good as the antenna. Radar is no exception. The larger the antenna, the narrower the horizontal beamwidth. Horizontal beamwidth determines the target discrimination e.g. if two adjacent targets are observed with a small antenna they might merge as one but with a larger antenna, with a narrow beamwidth, they will appear as two separate targets. Additionally, as the beamwidth is reduced the gain of the antenna is increased resulting in greater range. So always choose the largest antenna you can accomodate.
Furuno Radome 15"
The smallest radome from Furuno. An enclosed Microstrip antenna offers a 6.2° horizontal beamwidth and a 25° vertical beamwidth.
Furuno Radome 18"
The 18" radome houses a Microstrip antenna giving a 5.2° horizontal beamwidth and a 25° vertical beamwidth.
Furuno Radome 24"
he 24" radome has a 55cm hybrid array antenna reducing the horizontal beamwidth to 3.9° providing good target discrimination.
Furuno Open Array 3.5'
Coupled with the 10.4" display this 3.5' antenna with its 2.2° horizontal beamwidth and 22° vertical beamwidth gives outstanding performance for range and discrimination. This antenna is the choice of the larger motor yacht and commercial fishermen.
Furuno Open Array 4'
Almost the ultimate in small boat radar antennas the 4' open array is worth that little bit extra. Offering a horizontal beamwidth of 1.9° and vertical beamwidth of 22°
One more note is the range of the radar,
The open arrays provide greater power and more range. The dome units provide from 16 Nm to about 36Nm while the open arrays provide 24 Nm to 72 Nm. In general you want at least 24 to 36 Nm
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Tue May 01, 2007 6:13 am