A compact and simple interdigital capacitor inverted-F antenna (IFA) operated at its quarter-wavelength (λ/4) mode as the fundamental resonant mode for achieving multiband operation in the mobile phone is designed. The proposed antenna consists of a monopole antenna and an IFA. The proposed interdigital capacitor IFA has a simple structure of comprising two meandered radiating strips of length about λ/4 and is fed using an interdigital capacitor coupling feed. The two meandered radiating strips also generate two λ/4 resonance modes at about 900 MHz and 2100 MHz to cover the GSM850/900/1800/1900/DCS/PCS/UMTS bands and the 2.4 GHz WLAN (IEEE 802.11b) band operations. Further, the proposed antenna has a simple planar structure and occupies only a small area of 10×40 mm2 on the system circuit board of the mobile phone. This proposed antenna with multiband, broadband matched impedance, stable radiation patterns, constant antenna gains, good radiation efficiency and compact size can be suitable for mobile phone applications.
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