Mean effective gain analysis of a diversity antenna for portable telephones in mobile communication environments

An analysis of the mean effective gain (MEG) at 900 MHz of a diversity antenna for portable telephones comprising a whip antenna and a planar inverted F antenna (PIFA) has been done. The analysis was performed in free space, and no human body effects were taken into account. Wire-grid analyses yielded MEG characteristic results regarding whip lengths, body shapes, and inclinations of the radio from the vertical under various incident wave propagation environments. The results indicate that a whip antenna shows significant MEG changes with changing whip lengths, mean elevation angles, and standard deviations of incident waves. The results also demonstrate that a whip antenna shows maximum MEG values of -3 to -1.3 dBd for whip lengths of 0.5 to 0.57 lambda. When a whip antenna is less than a half-wavelength long, the MEG of the PIFA is greater than -6 dBd, with maximum values ranging from -3.5 to -3 dBd. With a cross-polarization power ratio (XPR) from -2 to -1 dB, the MEG becomes constant regardless of the inclination angle of the radio body. Furthermore, there are particular inclination angles at which the MEG remains constant regardless of the XPR value. The MEG degradation by 3 to 5 dB is observed when the body inclination changes from the vertical to the horizontal. The analyses clarify the relationship between the MEG in free space, antenna, and external environmental parameters. (C) 1999 Scripta Technica, Electron Comm Jpn.