Omnidirectional wrapped microstrip antenna: Concept, integration and applications

The concept of a novel quasi-omnidirectional low profile wrapped microstrip antenna element and its integration into a laptop computer is described. The antenna structure is obtained by wrapping a microstrip patch element around the top edge of a laptop screen. Numerical results show that the "Omnidirectional Wrapped Microstrip Antenna" (OWMA) input impedance and radiation pattern properties are almost independent of its location in the laptop screen top or side edges. The antenna properties, as a function of the screen angle, have been evaluated both numerically and experimentally. It is shown that the antenna input impedance is not significantly affected by the keyboard structure and does not depend on the inclination angle except when the laptop case is almost closed. The radiation pattern shows relatively small variations for the most commonly used screen angles. Linear arrangements of multiple antenna elements have been considered. An arrangement with six elements exhibiting low mutual coupling and coupling induced correlation, aiming at MIMO arrangements, has been fabricated and tested. In spite of tight element packaging the antennas maintain quasi-omnidirectional total gain pattern. Experimental results confirm the fulfillment of the requirements for MIMO applications in laptops.