No abstract

In this paper a quad-mode endfire planar phased antenna array with wide scan angle and 1.2 mm clearance is proposed for 5G mobile terminals. The proposed antenna can obtain over 8 GHz of impedance bandwidth. Here is suggested to efficiently combine a multi-mode array element with different radiation patterns for each mode into a phased antenna array. In the array, similar and wide embedded radiation patterns are obtained for the all four modes. Furthermore, a coaxial to differential stripline transition is designed in this work. The differential feeding structure is very compact and utilizes only MMPX connector and vias. The total scan pattern and coverage efficiency of the measured and simulated phased array antenna are calculated in the range from 25 to 33 GHz, and a good agreement between measured and simulated results is observed. The mean coverage efficiency along the frequency range is very similar, but minor difference in variance of coverage efficiency is observed in the measurements. The coverage efficiency of around 50 % for the threshold gain of 5 dBi is achieved in the chosen frequency range.

No abstract

A novel test facility for the efficient evaluation of microelectromechanical system (MEMS) switches and the development of alternative contact materials is described. The facility utilizes the upper cantilever from commercial MEMS contact switches, and tests these against alternative bottom contact materials within a modified atomic force microscope (AFM). The test closely approximates the real switch, but can accommodate a wider range of test conditions and contact materials. The facility allows alternative contact materials to be easily and quickly incorporated, and therefore evaluated by measuring the number of cycles to failure. The evolution of the wear surfaces of the switch contact materials under test can also be easily examined. In order to demonstrate the facility, the evolution of the contact resistance and wear of a commercial RF MEMS cantilever with Au contacts was monitored under accelerated test conditions, comparing the behavior of Au bottom contacts to an alternative Au-Ni alloy contact material. The Au-Ni (20 at.%) alloy displayed reduced wear rates and improved switch cycle lifetimes compared to pure Au, while retaining acceptable values of contact resistance.