LTE700/WWAN MIMO antenna system integrated with decoupling structure for isolation improvement

A novel decoupling structure which could be integrated into the system board of handheld wireless communication devices is proposed. By applying capacitor with the capacitance range of 1.8-3.3 pF, more than 260 MHz tunable isolation bandwidth could be achieved in the embodiment for the requirement of compact design area. The mutual coupling performance of dual-antenna module which having the spacing less than 0.1 wavelength is investigated and analyzed. The measured isolation characteristic of MIMO antenna operated at LTE700/GSM850/GSM900 frequency band is about 10 dB. In order to know the relations of antenna isolation performance and the variations of capacitance, a quantitative analysis in the antenna operating frequency range around 700-960 MHz is also developed. The simulated and the measured results confirm the effectiveness of our proposed decoupling structure.