Dual-loop antenna with band-stop matching circuit for WWAN/LTE full metal-rimmed smartphone application

A dual-loop antenna for hepta-band wireless wide area network (WWAN)/long term evolution (LTE) narrow-frame full metal-rimmed smartphone application is proposed and studied. Compared with recent reported works, the main advantage of this design is the ability to achieve narrow-frame (smaller ground clearance) with unbroken metal-rim (or full metal-rimmed). Due to the modification of top no-ground portion, a band-stop matching circuit is used in this case to compensate the impedance mismatch caused by this modification. By combining the six resonant modes induced by the proposed dual-loop structure with the additional lower resonant mode excited by the matching circuit, the proposed antenna can successfully cover both WWAN bands (GSM850/900/DCS/PCS/UMTS2100) and LTE bands (LTE2300/2500). A prototype of the proposed antenna is fabricated, and the obtained results including reflection coefficients, efficiencies and gains are also presented and discussed.