Wideband apertures for active planar multifunction phased arrays

The authors address the problem of providing an aperture that is consistent in its operational bandwidth and grating lobe requirements and is configurable as a phased array of transmit/receive (T/R) modules. The design and performance of wideband phased-array apertures and an active line array suited for multifunction system applications are discussed. It is shown that radar performance in multifunction systems with dual-polarized apertures can yield an active VSWR (voltage standing wave ratio) that is, on the average, below 2.0:1.0 over a ±60 degree scan in X-band. The mean active VSWR over the 6.0- to 18.0-GHz band scanning beyond 60 degrees (60 to 70 degrees) is below 3.3:1.0. It has been demonstrated that full polarization diversity can be accomplished and that the T/R circuit can be packaged in densities consistent with 18-GHz performance. It appears that 5 to 7 MMIC (monolithic microwave integrated circuit) chip X-band modules can be realized having 4- to 5-W output, 3-dB noise figure, and 30-dB gain for under $500