Body effect on characteristics of small loop antenna in pager systems

A small rectangular loop antenna has been studied and widely used as a mobile communication antenna especially in pager systems. Since it is usually installed in a pager and used very close to a human body, its effect against the human body has to be taken into consideration. For simplicity, the surface of the human body may be replaced by a conducting reflector. The authors experimentally and theoretically examine the influence of a reflector on the input impedance of a small loop antenna. Calculated results are obtained by using the method of moments and compared with experimental data. The validity of the method of moments is confirmed. Then, using the method, a positive effect of the human body on the actual gain of the antenna is found analytically. Simulations carried out using practical models seen in the pager show interesting characteristics of the capacitor-loaded small loop antennas.<>