Small-size LTE/WWAN coupled-fed loop antenna with distributed parallel resonant circuit

A small-size LTE/WWAN coupled-fed loop antenna with a rotated U-shaped strip for laptop-computer applications is presented. The coupled-fed loop antenna formed by a feeding strip and a coupled shorting strip can support two operating bands, both of which cannot cover the desired frequency bands. By embedding a rotated U-shaped strip into the coupled-fed loop to maintain the compactness of the antenna, a distributed parallel resonant circuit (PRC) is formed to expand the bandwidths of the lower band and the higher band. The proposed antenna has a uniplanar structure and is easy to be fabricated on a thin FR4 substrate with an area of only 10 × 50 mm².