Optimization of a dual polarization interleaved wideband spiral phased array
Résumé
Assuming the bandwidth is defined simultaneously for a RSLL less than −10 dB, an AR less than 3 dB and a VSWR less than 2, all of this for steering angles from −30° to +30°, this array has an approximate bandwidth of 4–5.25 GHz, or 27%. This bandwidth is valid for both polarizations. Figure 4 shows the AR, VSWR, and RSLL bandwidths. This figure clearly shows that the AR establishes the lowest frequency in the bandwidth, while the RSLL sets the highest frequency. The VSWR bandwidth extends beyond these limits. Thus, to increase the bandwidth, two possibilities remain and will be explored: • extend the lower limit of the AR; • extend the upper limit of the RSLL, this means decreasing the element spacing in the array, thus decreasing the size of the spiral.