A dual-band dual-polarization antenna using unequal crossed slots on metallic cavity

We present a design for a dual-band slotted cavity antenna with its bands having orthogonal polarizations in a shared aperture. The design and its simulated performance is presented at X-band, which is typical of many satellite radar applications, such as MDA's pending RADARSAT synthetic aperture constellation. The presented antenna comprises a 2×2 array of crossed-slots which have unequal arm lengths, cut on a rectangular metallic cavity and fed by a crossed waveguide feed. This design demonstrates (by simulation) an impedance bandwidth close to 10% for both frequency bands with an overall isolation between the ports better than 30dB. A directivity of 12 dBi was obtained in both polarizations, which corresponds to aperture efficiencies of 73% and 46% for the lower and higher frequency bands respectively. This antenna can be considered as a sub-array for larger array realizations.