Multi-band 2-port MIMO antenna design for LTE-enabled 13″ monocoque laptop

A new trend in design of high-end laptops has recently become popular. Plastic enclosures were superseded by a monocoque shells e.g. aluminium shells as they provide more durability to the product. However, they have proved to be a challenge for antenna design as the monocoque structure has to be broken to allow for antenna placement. The designs applicable to Wireless Local Area Network (WLAN) frequency band antennas involve mounting planar inverted-F antennas (PIFAs) on the frame of the optical drive opening, behind the logo or in the slot between the lid and the base part of a device. A more general design approach shown in this paper uses the slot between the lid and the base part of a laptop in order to place the exciters (couplers) and conductive hinges both of which electrically connect the base part with the lid. Optimization of their position over the length of the slot yields a solution in which couplers excite mutually orthogonal superpositions of radiation modes in the desired frequency bands. In order to validate the concept a multi-band 2-port Multiple Input - Multiple Output (MIMO) antenna for Long Term Evolution (LTE)-enabled 13" monocoque laptop was designed and fabricated. It features higher than 7 dB Total Multi-Port Return Loss (TMRL) over the desired LTE low-band (Europe) (790 MHz - 960 MHz) and LTE mid-band (1710 MHz - 2170 MHz) frequency bands.