This research focuses on improving the draincurrent and radio-frequency properties of a T-gate E-mode AlInN/GaN HEMT with a BGaN back barrier. The results indicate that the boron gallium nitride back barrier may restrict the two-dimensional electron gas (2DEG) in the channel region and efficiently suppress the short channel effects. The BGaN back barrier HEMT with just a 2% B-component greatly improves the device’s analog and RF performance over a normal GaN buffer HEMT such as transconductance (0.15 S), intrinsic gain, early voltage (4.24 V), cut-off frequency (141 GHz) GFP (356 GHz), GTFP (4.6 THz), and transconductance frequency product (6.5 THz). Therefore, the device with a BGaN back barrier has considerable potential for use in applications requiring extremely linear devices that operate at high frequencies and high gain powers.
A design method for transmission-type broadband invisible cloaks is presented. An invisible cloak for hiding a much larger rhombus area than the wavelength is designed by using straight and meander transmission-lines and those line lengths are calculated from theoretical formulas. Circuit simulations are carried out and the broadband operations of the designed invisible cloak are demonstrated from the calculated results of the complex voltage distributions.
A compact size, low-weight, low-cost, Triple band antenna is intended for lower gigahertz applications. To make a Koch fractal antenna, a regular rectangular patch is modified with rectangular slots along the bottom edges on the left and right and a narrow triangular cut along the patch's intense top, left, and right sides. The Computer simulation technology (CST) Studio 2017 software simulator, which uses FDM (finite-difference methods) is used to study this structure. For low manufacturing costs, the suggested antenna is incredibly simple to combine with microwave circuitry. To design a triple-band micro strip antenna with frequency bands of 0.72 GHz, 3.89 GHz, and 5.45 GHz, Koch technique is suggested in this study. When the Koch fractal micro-strip antenna is used, the simulation results show that the antenna operates in tri - bands with return losses of -20.1 dB, -26.24 dB, and -11.79 dB at 0.72 GHz, 3.89 GHz, and 5.45 GHz respectively. The antenna is constructed on a Jeans substrate that has a permittivity with 1.71 and a thickness with 0.81 mm.
A dielectric resonator antenna with a T-slot configuration based on substrate integrated waveguide is proposed for a 3.5 GHz 5G application. A SIW structure with a T slot is etched on the top surface plane of the Rodger 5880 substrate, and the dielectric resonator is then mounted to the T-slot. A 50-ohm coaxial cable is used to feed the antenna, placed at the appropriate position. The performance analysis of a dielectric resonator antenna with T slot configuration supported by substrate integrated waveguide (SIW) has been investigated. Parametric studies on various parameters to improve the performance in terms of gain, impedance bandwidth, surface current, and impedance matching behaviors are observed. The simulated result of the proposed dielectric resonator antenna supported by SIW shows a reflection coefficient of more than 10 dB in desired frequency at 3.5 GHz which is in good agreement with the simulated results. In this study, the gain of the T-slot antenna was 5.01 dB. All simulations are done using Computer Simulation Technology (CST) software. The designed antenna structure with specified materials and related values respectively makes it a potential candidate for future 5G particularly for sub-6 GHz technology.
An effective method to enhance Adjacent Channel Leakage Ratio (ACLR) and Error Vector Magnitude (EVM) in the presence of multitone amplitude and phase variation within the carrier band and adjacent frequencies for power amplifiers using predistortion is developed and demonstrated for 5G Systems. The effects of multiple tones with varying amplitude and phase are studied and the closed form relations for predistortion coefficients are obtained for cancellation of the intermodulation products. The proposed method was then verified through physical measurements using a commercial power amplifier where reduction of intermodulation was achieved, and the adjacent leakage ratio performance was improved.
