JRC

Appendix 1
Antenna Systems

            Unusually, the product-line for JRC, as advertised, indicates little flexibility in the use of antennas, and thus a much closer correlation between antenna size and peak power output than with other manufacturers' products. This may be more apparent than real: other manufacturers may indicate feasibilities, where JRC sales literature indicates the obvious - that antenna components and transmitter should be matched. In X band,

• The only JRC model with a 12" radome is also the only model with a 1.5 kW peak power output;
• 18-inch radomes are invariably documented with a 2-kW peak power output;
• 24-inch radomes have a 4-kW peak power output;4-foot open-array models have power outputs of either 6 or 10 kW;
• 6-foot open-array models have power outputs of 10 or 25 kW; and
• Larger open-array models have 25 kW peak power outputs.

In S band, the only 60-kW model is designed for pelagic fishing vessels, and has an 8' open-array antenna; all other models use a 12-13' antenna with a peak power output of 30 kW.       

            Care must be taken in interpreting antenna sizes. Where radomes are concerned, JRC invariably cites the external diameter. With open arrays, every effort has been made to identify both the physical and the radiating length; in most instances, the physical length is provided as the turning diameter, which, in the case of end-fed slotted waveguides, may be significantly greater than the radiator, typically by around 6 inches. Table 1, which summarize the principal features of the various JRC antenna systems and lists the radar models associated with each, shows physical length and JRC-documented beam characteristics. Note that there are three boxes describe S-band devices, highlighted with a pastel background.

Table 1, JRC Antenna systems here