Dynamic Radiation Pattern of a Two-Element Antenna Array with Spatial Amplitude Modulation

We characterize the dynamic complex radiation pattern of a two-element antenna array employing spatial amplitude modulation. By altering the relative amplitude ratio between the two antennas over time, the array phase pattern changes dynamically as a function of time and angle, while the amplitude pattern remains largely constant over the majority of the modulation. We analyze the complex radiation pattern of a two-element array consisting of two microstrip patch antennas designed to resonate at 2.5 GHz through simulation, characterizing the patterns from a continuously dynamic amplitude ratio and that from a discrete set of amplitude ratios. By changing only the amplitude ratio of the antenna input signals, the effective radiated power is independent of the amplitude ratio. Experiments were conducted using a 2.5 GHz two-element array with discrete amplitude ratios, demonstrating the complex dynamic radiation pattern.