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A p-i-n diodes-controlled radiation-pattern reconfigurable phased array for fifth-generation (5G) handsets is proposed in this article. The proposed beam scanning and switching hybrid system can significantly reduce the number of arrays and transmit–receive (TR) components when compared with multiarray systems while keeping the same spatial coverage. The array has wide working band from 24 to 27.5 GHz, which can cover the allocated 5G band for Europe. The four-element array is planar with a small clearance of only 4 mm, which is suitable for most of the current mobile phones. Each reconfigurable array element is fed by one shielded stripline and has three switchable radiation patterns: two broadside directions and one endfire direction. The beam switching is realized by applying two reconfigurable directors on both sides of the dipole, which also reduces the antenna profile. The directors are activated when the p-i-n diodes are at OFF mode, which minimizes the energy loss on the p-i-n diodes. The parasitic influence of the p-i-n diodes, the soldering process, and mobile environment are discussed in detail. The measured results show good agreement with the simulations. [ABSTRACT FROM AUTHOR]

Linearity characteristics of capacitive tuners under large radio frequency (RF) power have become an important issue for today’s cellphone industry. The use of these devices as antenna tuners has become critically important due to the RF spectrum opening in the low-frequency range. Capacitive tuners connected directly to the antenna to change the RF voltage/current pattern and tune lower frequencies are subjected to suffer large voltage swings, especially in the isolation state or minimum capacitance. In this article, we analyze the effects of the large RF power or equivalent rms voltage to capacitive micro-electromechanical systems (MEMS) switches. The theoretical analysis combined with Coventor MEMS+ simulations will allow us to study the capacitance change and MEMS mechanical frequency response. This article evaluates two types of measurement setups to investigate the RF power effects on nominal capacitance and mechanical frequency response. Measurements up to 6 W were completed with two capacitive MEMS tuner products, confirming the modeling predictions and demonstrating the robustness of this technology under large RF power or voltage swings. [ABSTRACT FROM AUTHOR]

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. In this paper, it is suggested to efficiently combine a multimode 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 paper. 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 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. [ABSTRACT FROM AUTHOR]

Dielectric charging is one of the key topics concerning microelectromechanical capacitive switch reliability; however, very little is known about how charge is generated on an exposed dielectric surface when brought in contact with another dielectric surface under high electric field. In this paper, we analyze and propose a model of surface charge generation of a microelectromechanical device produced by triboelectric effects under high electric field. A simplified theory has been developed that can be used either for electron or ion transfer, where a closed-form analytical solution is achieved under certain conditions. Measurements were performed during continuous hold-down stresses under different voltages and temperatures. The results based on pull-in voltage shift were fit using a MATLAB program where surface dielectric properties were extracted. The results show a qualitative agreement with the developed theory, and the extracted parameters can help to understand and predict the product reliability, as well as define a fabrication process screening procedure. [2015-0268] [ABSTRACT FROM AUTHOR]

This paper presents a novel direct calculation method for matching network adaptive control utilizing an analytic algorithm based on an integrated measurement of load impedance. In principle, this approach has no limitations on the match tuned load impedance and the operating frequency, but in practice its operation is restricted by the matching network tolerances and the accuracy and dynamic range of the load impedance measurement circuitry. The matching network consisting of microelectromechanical systems tunable capacitors and high-Q fixed inductors is one of the best choices for this loop since it has a broad match tuning range across loads condition and frequencies. [ABSTRACT FROM PUBLISHER]

In this paper, a novel frequency control loop system for tunable notch filters is presented. The frequency control loop is designed for automatically tuning a microelectromechancial systems tunable notch filter, which has 22-dB rejection in the notch band and less than 0.8-dB insertion loss over a 5-MHz passband bandwidth in the International Mobile Telecommunications band (2.1 GHz). The filter frequency control loop is based on sensing the reflection phase change of a reference signal (in this case, the transmitter carrier) and is developed to track the transmitter operation frequency. [ABSTRACT FROM PUBLISHER]