Small-Size Loop Antenna With a Parasitic Shorted Strip Monopole for Internal WWAN Notebook Computer Antenna

A simple meandered loop antenna with a parasitic shorted strip monopole, both printed on a thin dielectric substrate and folded to occupy a small size of 50 x 10 x 4 mm(3), for the internal penta-band WWAN notebook computer antenna is presented. The antenna can provide two wide operating bands to cover the GSM850/900 operation (824-960 MHz) and the GSM1800/1900/UMTS (1710-2170 MHz) operation. The lower band is formed by two resonant modes, one half-wavelength loop mode contributed by the meandered loop and one quarter-wavelength monopole mode contributed by the parasitic shorted strip. The upper band is mainly formed by two higher-order loop resonant modes, with their good impedance matching obtained owing to the parasitic shorted strip. Further, in order to decrease the effects of the display ground and keyboard ground of the notebook computer on the antenna performances, two linear slits are embedded in the keyboard ground near the two connection hinges between the two grounds. The two linear slits function as current traps and can effectively reduce the excited surface currents on the keyboard ground. This leads to decreasing size of the effective notebook computer ground plane seen by the antenna. Thus, degrading ground plane effect on the performances of the internal WWAN antenna can be greatly reduced.