A Low-Profile and Wideband PILA-Based Antenna for Handset Diversity Applications

A low-profile (5 mm) and wideband planar inverted-L antenna (PILA) is proposed for handset diversity and MIMO applications. It occupies a footprint area of
$702 (= 351 \times 2) ~\hbox{mm}^2$
over the ground plane and consists of two elements arranged utilizing both pattern and spatial diversities to provide a reasonable isolation level. The radiators consist of modified PILAs coupled with a ground plane notch that works as a parasitic radiator; a small ground plane strip is added to shift the lower edge frequency down to 1700 MHz. The single-element and dual-element antennas are analyzed in terms of the reflection coefficient and antenna impedance. Prototypes are made and the measurement results show that this design is good for mobile applications over the frequency range 1700–2850 MHz with a fractional bandwidth of 51%; it covers applications such as DCS 1800, PCS 1900, UMTS, LTE 2300 and LTE 2500, Wi-Fi, and Bluetooth (2400-2448 MHz). Finally, the diversity performance parameters are obtained and evaluated based on both simulation and measurement results. It is demonstrated that the proposed antenna design is a promising candidate for wireless hand-portable applications.