A double layer stacked patch antenna with a size of 200×200×48mm3 is proposed in this investigation. To achieve a broad CP bandwidth that can cover universal UHF RFID applications (840-960MHz), a slot loaded circular patch antenna fed by an L-shaped probe is designed as the lower layer (main patch), while the top layer (parasitic patch) is a simple circular patch loaded with a cross-slot of dissimilar arm lengths. Besides demonstrating a broad 10-dB return loss bandwidth of 16% (823-966MHz) and a CP bandwidth (3-dB axial ratio) of 14.0% (837-963MHz), the proposed antenna also yields maximum gain and minimum radiation efficiency of 8.8dBic and 85%, respectively, across the universal UHF RFID bands.

A compact uniplanar antenna design for tablet/laptop applications is proposed. The main design principle of this antenna is the use of the coupling-feed mechanism. The proposed antenna is composed of an inverted L-shaped parasitic element, T-shaped feeding strip, parasitic shorted strip, and a step tuning stub. With its small size of 55mm × 15mm × 0.8mm, the proposed antenna is able to excite dual wideband transmission over the full LTE/WWAN operation ranges of 698-960MHz and 1710-2690MHz. Furthermore, the proposed antenna also exhibits reduced ground effects, such that reducing the ground size of the proposed antenna will not affect its performance.