Increasing the Bandwidth of Antennas Based on the Frequency Pulling Technique: Theoretical Limitations and Practical Considerations

In this work, we investigate the theoretical limitations of the frequency pulling technique (FPT), a newly introduced technique that uses the insertion loss design methodology of bandpass filters for increasing the bandwidth (BW) of antennas. Notably, we show that by applying the FPT on antennas, the maximum theoretical impedance BW defined by the Bode–Fano criterion is achieved. In addition, we demonstrate that the impedance BW based on the Bode–Fano limit can exceed the BW defined by the radiation efficiency (RE) of an antenna. This finding is very important since it shows that the practical BW limit of an antenna is imposed by its RE. To validate our findings, we apply the FPT on various traditional microstrip patch antennas and determine their theoretical and measured BW.