Inverted-F antenna with parasitic elements for TETRA handset

The paper presents the VSWR (voltage standing wave ratio) performance and radiation pattern for a low-profile IFA (inverted-F antenna) matched at 450 MHz. It is known that when the IFA height from a conducting ground plane is approximately one-tenth of the wavelength, the frequency bandwidth for a VSWR=2 criterion is approximately 8%. Nakano et al. (1998) proposed two L-figured parasitic elements added to the IFA to widen the VSWR bandwidth. It should be a large value for handset systems if this criterion is applied to structures working at lower frequencies (450 MHz) such as TETRA. A design of IFA is presented with different lengths for parasitic elements to generate two resonance frequencies near the central frequency of design. Antenna characteristics; mounted on the handset, are calculated using the method of moments (MoM) with wire grid models using numerical electromagnetic code NEC2. The mean effective gain (MEG) for different statistical distribution models of incident waves are presented too.