Detailed analysis and numerical simulation of EM coupling effects of a human body on radiation characteristics of a circular loop antenna to simulate the pager's internal antenna is presented. The orientation of the loop antenna proximate to the waist position of a human body is either perpendicular or parallel to the body. The antenna characteristics, such as the antenna input impedance, radiation patterns/polarizations, radiation efficiency (reduced by the body absorption effect), and directive gain and power gain, etc., affected by the human body are numerically computed. Coupled integral equations (CIE) and the method of moments (MoM) are employed to numerically solve this antenna-body coupling problem. The magnetic frill source model is employed for the antenna feed modeling. Numerical examples are presented for the loop antenna of different orientations and positions at 280 MHz. It is found that the body may enhance the directive gain and fill the null of the pattern of the loop antenna. Also, the input resistance of the loop antenna (radiation resistance) increases 5 to 6 times due to the body coupling. These are positive effects of the body. However, due to the human body absorption effect, the antenna radiation efficiency may decrease to less than 5% if the loop orientation is perpendicular to the body and to about 50% to 60% if parallel to the body. These are important for the antenna and RF matching circuit design and communication link-budget consideration in mobile paging systems.
|Number of pages||11|
|Journal||Journal of the Chinese Institute of Electrical Engineering, Transactions of the Chinese Institute of Engineers, Series E/Chung KuoTien Chi Kung Chieng Hsueh K'an|
|Publication status||Published - 1997 May 1|
All Science Journal Classification (ASJC) codes
- Electrical and Electronic Engineering