Concentric ring array of connecting spirals with interleaved WAVES

In a previous work, a concentric ring array (CRA) of spiral antennas was designed. Its specifications were a bandwidth of 2:1, the capability to scan up to 30°, dual circular polarization with an axial ratio (AR) <; 3dB, relative sidelobe level (RSLL) <; -10 dB and reflection coefficient (S11) <; -10dB. By connecting the arms of the neighboring spirals we were able to expand the S11 bandwidth in the low frequencies. In order to expand the RSLL bandwidth in the higher frequencies, we used the WAVES (Wideband Array with Variable Element Size) technique by interleaving the concentric ring array (CRA) rings of spirals with rings of spirals with half their size. By combining those techniques, we achieved a bandwidth of 15:1.