A fully integrated solution providing scan-beam capability with a single antenna is presented in this paper for the first time. The proposed system includes a reconfigurable rectangular spiral antenna with a set of micro electro mechanical system (MEMS) switches, which are monolithically integrated and packaged onto the same substrate. The system is based on a single-arm rectangular spiral antenna, capable of changing its radiation pattern using radio frequency-MEMS (RF-MEMS) switches. The rectangular spiral and RF-MEMS switches are monolithically integrated on a conventional microwave substrate printed circuit board (/spl epsiv//sub r/=3.27 and tan/spl delta/=0.004) and quartz substrate (/spl epsiv//sub r/=3.78 and tan/spl delta/=0.0002). The spiral is made out of multiple lines, which are interconnected by RF-MEMS switches strategically located along the spiral. On activating these switches, the spiral overall arm length is changed and consequently its radiation beam direction is changed. The two proposed antennas radiate right hand circular polarization (RHCP) and left hand circular polarization (LHCP) for printed circuit board and quartz substrate respectively. The gain of the two antennas varies between 3/spl sim/6 dBi. They both satisfy the 3-dB axial ratio criterion at their operating frequency band, i.e., at 10 GHz and 6 GHz for the printed circuit board and the quartz substrate respectively. To the best of our knowledge, this is the first truly reconfigurable printed antenna design using MEMS devices as active elements integrated in the same low loss substrate. The excellent performance of the proposed system emphasizes the importance of being able to integrate MEMS switches into the same low loss substrate for antenna applications. This technology pioneers the design of arbitrarily shaped reconfigurable antennas including the design of reconfigurable antenna arrays.

This communication presents the design, fabrication and measurement of transparent antennas with metal mesh (MM) for wireless transparent applications such as smart windows, transparent mobile devices, transparent-internet of things (IoT), etc. The MM was proposed as a transparent electrode with high conductivity in electrical performance, with proper transparency in optical performance and low fabrication cost compared to a traditional transparent thin film electrode. To analyze the performance of a transparent antenna fabricated by MM, the antennas were designed to operate in the 2.4 ~2.5 GHz WLAN band (802.11b). The conductive metal of transparent MM patch antennas was designed using a square-lattice structure and was fabricated using wired metal mesh (WMM) with copper wire (0.2 mm -0.5 mm). In addition, micro metal mesh film (μMM) consisting of thin copper wire (20 μm) was used to fabricate transparent patch antennas. The realized gain, efficiency, front-to-back ratio and radiation patterns of the transparent MM patch antennas are discussed for various combinations of radiator and ground planes. Overall, the transparent MM patch antennas offer optical transparency, maintain sufficient performance and could possibly be used in wireless transparent applications.

This paper aims to design, fabricate, and analyze transparent and flexible monopole antennas for an application in wearable glasses. A multilayer electrode film composed of 100-nm-thick indium-zinc-tin oxide (IZTO)/Ag/IZTO (IAI), a type of transparent conducting oxide electrodes, is selected as the conductors of antennas and ground planes of the wearable glasses. The average transparency of the proposed antennas is measured to be 81.1% in the visible wavelength, and the electrical conductivity of the proposed antennas is measured to be 2 000 000 S/m. The proposed antennas are fabricated with physical vapor deposition process in high vacuum. Moreover, nontransparent antennas made of a 40-nm-thick silver (Ag) thin film are designed and fabricated to compare their performances with the transparent IAI antennas. To reduce the electromagnetic field absorption of the human head, we introduced and analyzed three configurations (types A-C) of monopole antennas having different directions of radiation patterns. The fabricated IAI antennas show the average efficiency of 40% and 4-dBi peak gain at 2.4-2.5 GHz. Furthermore, they have a specific absorption rate lower than 1.6 W/kg, which complies with the Federal Communications Commission standard, when the input power is 15 dBm, which is Google Glass's.

This letter presents transparent microstrip patch antennas made of two types of transparent conductive films, which are multilayer film (MLF; IZTO/Ag/IZTO) and metal-mesh film (MMF; Cu). The sheet resistance levels of the MLF and MMF are 2.52 and 0.18 Ω/□. The transparencies of the MLF and MMF are over 80% and 60% at a 550-nm wavelength, respectively. The design and dimensions of the antennas follow the conventional simple microstrip patch antenna. A transparent acryl substrate is used for the proposed transparent antennas. The conductive parts of the proposed antennas are also made of copper sheets (CS; case 1) for the performance comparison to two types of transparent antennas made of MLF (case 2) and MMF (case 3). The resonance frequency band of the antennas is 2.4-2.5 GHz for Wi-Fi service. The case-1, case-2, and case-3 antennas have peak gains of 4.75, -4.23, and 2.63 dB and have radiation efficiencies of 66.32%, 7.76%, and 42.69% at the center frequency of the Wi-Fi service band (2.45 GHz), respectively.

This paper presents a magnetic resonance wireless power transfer (WPT) system that uses three coils, a planar receiver and operates at 6.78 MHz,. Effective power transfer is ensured by establishing an impedance matching condition for this WPT system. A metamaterial (MTM) array having dimensions of 20 cm X 30 cm is also positioned near the load coil to concentrate the magnetic field and enhance the transfer efficiency. The result is a maximal improvement of 27% in the transfer efficiency at a transfer distance of 50 cm. The impact of a ground plane on the transfer efficiency is also examined. By utilizing the MTM array, making slits on the ground plane and increasing the gap between the ground plane and the load coil, it is possible to mitigate this impact. The highest transfer efficiency improvement is about 55% at a distance of 20 cm with the ground plane. A practical laptop model is fabricated to verify the impact of the load coil angle and position on the transfer efficiency. The result shows that the maximum transfer efficiency with the laptop model is 47.58% with the load coil angle of 90 degree.

Reconfigurable beam steering using a microstrip patch antenna with a U-slot is proposed for wearable fabric applications. The proposed antenna was manufactured on a fabric substrate and designed to steer the beam directions at the operation frequency of 6.0 GHz. The U-shaped slot and a proximity-coupled feeding technique are applied to design the proposed antenna. By configuring two artificial switches between the proximity-coupled feed and the antenna patch, the antenna is given three beam directions (S0, S1, and S2). The maximum beam directions are steerable in the yz -plane (θ = 0° , 30° , and 331° , respectively), and the overall HPBW is 115°. The measured peak gains are 6.11-6.69 dBi.