Numerical analysis of the radiation characteristics of the meander line antennas consisting of two strips

With the development of mobile terminal equipment, the demand for smaller handsets has increased. The size of many devices are decreasing, however, it is difficult to reduce the size of an antenna, that is, there are problems of impedance matching, bandwidth and radiation efficiency with down sizing. Currently, in a personal radio system, a whip antenna, a planar inverted F antenna (PIFA) and a helical antenna in the normal mode are used. The PIFA and helical antenna satisfying the condition that their sizes are smaller than /spl lambda//2/spl pi/ (1 radiansphere) are well known as a reference of a small antenna. The PIFA is not thin, while the normal mode helical antenna needs a matching circuit because of the small radiation resistance. The radiation characteristics of a meander line antenna are described and a method of improving the matching by using two strips are shown. The impedance matching is considered on the basis of its equivalent circuit and an analysis of the current distributions of the meander line antennas is carried out.