Capacitively loaded electrically small loop antennas with inductively and capacitively coupled feeds

The paper presents two capacitively loaded electrically small loop antennas (ESLA): one is with an inductive coupled feed and another with a capacitively coupled feed. Equivalent circuits are developed to help better understand the working mechanisms. A summarization of the ESLAs with coupled feeds is given to indicate that both inductively and capacitively coupled feeds can be modeled as transformers, which are the keys to impedance matching. A design procedure is also given to guide the design of the capacitively loaded ESLAs.