Capacitively FED hybrid monopole/slot chip antenna for 2.5/3.5/5.5 GHz WiMAX operation in the mobile phone

In this study, a promising design of the capacitively fed hybrid monopole/slot chip antenna for the 2.5/3.5/5.5 GHz WiMAX (worldwide interoperability for microwave access) operation in the mobile phone is presented. The antenna is printed on a thin FR4 substrate of small size 5.2 × 16 mm 2 as a surface‐mount element to be placed at one corner of the system circuit board of the mobile phone. The antenna mainly comprises a resonant monopole patch, a resonant shorter slot, and a matching longer slot; the latter two slots are embedded within the monopole patch to achieve a compact integration. Two wide operating bands centered at about 3.3 and 5.5 GHz are generated through capacitive excitation of the resonant monopole patch and the shorter slot, while the matching longer slot helps to improve the impedance matching over the two operating bands. The lower band covers WiMAX operation in the 2.5 GHz (2500–2690 MHz) and 3.5 GHz (3300–3700 MHz) bands, while the upper band covers the 5.5 GHz (5250–5850 MHz) WiMAX operation. Details of the proposed hybrid monopole/slot chip antenna are presented.