DUAL-BAND CIRCULAR POLARIZED SLOT ARRAY ANTENNA IN SUBSTRATE INTEGRATED WAVEGUIDE USING TWO PROPAGATION MODES FOR COMMUNICATION SATELLITES TRANSCEIVERS

摘要： A novel dual-band circularly-polarized slot array antenna aimed at LEO satellites communications where up-link and down-link operate at di?erent frequencies is introduced. By using higher order modes, the slots can be placed at points where current distributions are null for the fundamental mode. According to this idea, at the receiver frequency band the slots are placed to be excited by mode T E10 currents distribution, and at the transmitting band slots are forced to radiate according to mode T E20 currents distribution. A matching load termination is used to generate the required travelling wave to obtain the circular polarization, introducing low dissipation losses. Additionally, in this investigation an antenna feeder is also designed. Both the feeder and the slot antenna array are designed using Substrate Integrated Waveguide (SIW). The use of SIW makes easier the design of the transitions from the array to the microstrip input lines and the grounded-coplanar termination as well, relaxing fabrication constraints and tolerance.