Abstract-A new design for a compact and wideband circularly-polarized rectenna with high efficiency operating at X-band is proposed. A dual-slot coupled antenna excited by an H-shaped slot fed by a T-shaped microstrip is designed to yield wideband performance as a receiving array antenna. Rectifying circuit models for harmonic suppression circuit, impedance matching, DC-pass circuit, and DC return circuit at the input and output of the diode are built up and optimized to transfer the maximum power from the antenna to the load using an ADS circuit simulator. An RF-DC conversion efficiency of 71.9% is measured on the conditions of 300 Ω load, and 50.1 mW RF input power at 9.5 GHz operating frequency. For the proposed wideband rectenna, the efficiency of more than 50% is measured over a 1 GHz frequency bandwidth. The measured gain, axial ratio, and return loss of the circularly polarized antenna with a 4-element array are 11.2 dBi, 1.1 dB, and −16.4 dB, respectively. The reflection coefficient of the array antenna is measured at less than −10 dB over a wide frequency range of about 2 GHz. Using this antenna as transmitting (TX) and receiving (RX) radiators, the free-space power transfer capability of the rectenna is tested in free space to turn on an LED at 25 cm distance.

In this study, an eight-channel wide-band intermediate frequency (IF) receiver with an S-band input frequency, an output frequency of 200 MHz, and a signal bandwidth of 160 MHz was developed. The performance measurement results of the IF receiver showed that the fundamental signal and the second harmonic signal were involved in the bandwidth of the IF receiver output. This was caused by the nonlinearity characteristics of the final stage amplifier. Therefore, the final stage amplifier was changed to a differential amplifier, and the circuit of the IF receiver was modified to reduce the second harmonic signal. After improvement, an IF receiver with a gain of 33 dB, Output 1 dB Gain Compression Point(OP1dB) of > 15.8 dBm, 3rd Output Intercept Point(OIP3) of > 25.7 dBm was developed.The second harmonic suppressions were in the range of −83.30 dBc to −75.19 dBc when the fundamental signal output power was −10 dBm. This result satisfied the requirement of the system for the second harmonic suppression that was lower than −70 dBc.

We developed a 0.1‐μm metamorphic high electron mobility transistor and fabricated a W‐band monolithic microwave integrated circuit chipset with our in‐house technology to verify the performance and usability of the developed technology. The DC characteristics were a drain current density of 747 mA/mm and a maximum transconductance of 1.354 S/mm; the RF characteristics were a cutoff frequency of 210 GHz and a maximum oscillation frequency of 252 GHz. A frequency multiplier was developed to increase the frequency of the input signal. The fabricated multiplier showed high output values (more than 0 dBm) in the 94 GHz–108 GHz band and achieved excellent spurious suppression. A low‐noise amplifier (LNA) with a four‐stage single‐ended architecture using a common‐source stage was also developed. This LNA achieved a gain of 20 dB in a band between 83 GHz and 110 GHz and a noise figure lower than 3.8 dB with a frequency of 94 GHz. A W‐band image‐rejection mixer (IRM) with an external off‐chip coupler was also designed. The IRM provided a conversion gain of 13 dB–17 dB for RF frequencies of 80 GHz–110 GHz and image‐rejection ratios of 17 dB–19 dB for RF frequencies of 93 GHz–100 GHz.

The prevalence of schizophrenia is gradually increasing worldwide. Many patients with schizophrenia have a diminished ability to empathize and to detect their own emotions or those of others, deteriorating their social functioning and their quality of life. Nonetheless, emotional management training may improve patients’ emotion recognition, emotional expression, and negative symptoms. Developing and applying a short but effective program that reflects the current medical environment, in which hospital stays are ever-diminishing, is warranted. This one-group, pretest–posttest, quasi-experimental pilot study aimed to examine the effects of a short emotional management program (EMP-S) on 17 patients with chronic schizophrenia. Participants were patients hospitalized in the National Center for Mental Health in Korea. After the completion of a twice-a-week, eight-session, four-week long EMP-S, participants showed improvements in emotion recognition, emotional expression, and negative symptoms. Our results suggest the applicability and potential effectiveness of the EMP-S, which takes the length of psychiatric hospital stay and the inpatient environment into consideration. To minimize any barriers to social functioning in the post-discharge lives of inpatients with chronic schizophrenia and enhance their social cognition—by improving their emotion recognition, emotional expression, and negative symptoms—we suggest the periodical administration of this EMP-S to these inpatients.

A 100-nm gate-length metamorphic high electron mobility transistor(mHEMT) with a T-shaped gate was fabricated using a two-step gate recess and characterized for DC and microwave performance. The mHEMT device exhibited DC output characteristics having drain current(I dss), an extrinsic transconductance(g m) of 1,090 mS/mm and a threshold voltage(V th) of −0.65 V. The f T and f max obtained for the 100-nm mHEMT device were 190 and 260 GHz, respectively. The developed mHEMT will be applied in fabricating W-band monolithic microwave integrated circuits(MMICs).