Aperture Taper Control of a High Efficiency Low Sidelobe Series-Fed Antenna Array

A new method of implementing an aperture taper of a series-fed microstrip antenna array is introduced whereby the amplitude coupling is controlled by varying the size of slots. A design example is presented for an 8×34 array designed for 20 GHz with the goal of producing a sidelobe level of -40 dB. To achieve this, a -40 dB Chebyshev taper is chosen, and this is implemented using the new method of slot coupling. From full-wave simulation, the amplitude distribution is found to closely match the desired aperture taper when choosing a distribution of slot sizes that follows an exponential function. Results show a realized gain of 20.9 dBi, a radiation efficiency of 90.2%, and the highest sidelobe at a level of -38 dB. Non-uniform element spacing was used to compensate for phase errors. Future work discussed includes the fabrication and testing of a prototype array and further study into deriving an analytical method for determining the slot sizes to implement an arbitrary aperture taper for a series-fed array.