In this thesis, WWAN/LTE and LTE MIMO antennas for ultrabook computers are presented. The MIMO antenna system comprises an eight-band LTE/WWAN antenna and a three-band LTE antenna. The bandwidth of the eight-band LTE/WWAN antenna is enhanced by using an embedded parallel resonant circuit, which can result in dual-resonance excitation of the lowest resonant mode of the antenna. The bandwidth of the antenna¡¦s lower band can hence cover the LTE700/GSM850/900 operation. A design technique of improving the isolation of the MIMO antenna system is also presented. The isolation enhancement is obtained by embedding a 0.5-wavelength slot in the conductive supporting plate of the upper cover of the ultrabook computer. The embedded slot can attract the excited surface currents in the conductive supporting plate and decrease the coupling between the MIMO antennas through the coupling of the surface currents. The isolation between the MIMO antennas can hence be enhanced. Moreover, this technique will not lead to decreased radiation efficiency and impedance matching of the MIMO antennas, which is attractive for practical applications.