Return loss

About: Return loss is a research topic. Over the lifetime, 11090 publications have been published within this topic receiving 97603 citations.

Improvement of Return Loss Bandwidth of Balanced Amplifier Using Metamaterial-Based Quadrature Power Splitters

Abstract: A new balanced amplifier (BA) using metamaterial-based quadrature power splitters (QPSs) is presented in this letter. Instead of using conventional 90 couplers, the developed BA is implemented by two parallel amplifiers with broadband metamaterial-based QPSs at input and output ends. Since the QPSs can provide a broadband quadrature phase difference between two outputs, the input/output reflections from two amplifiers can be effectively cancelled over a wide bandwidth. The developed BA demonstrates the input/output return loss of better than 10 dB from 1.2 to 3.5 GHz with 97.9% relative bandwidth.

An Optimized Isolation Network for the Wilkinson Divider

Abstract: We propose an isolation network to simultaneously improve the input return loss, output return loss and isolation of the Wilkinson power divider in a wide bandwidth. The required even mode and odd mode reflection coefficients of the isolation network are calculated. Constructed even and odd mode circuits are combined to give the desired isolation network. Analytical expressions for the optimal component values for a single-section divider are given. Compared with the single-section Wilkinson divider, the final design can triple the bandwidth for an input-output return loss and isolation of greater than 25 dB. Broadband characteristic is achieved without increasing the number of sections hence extra length and insertion loss are avoided. Wide operation bandwidth of the new divider is verified by experimental results. The proposed method can be applied to a two-section divider, also broadening its bandwidth.

Compact Ultra-Wide Band MIMO Antenna System for Lower 5G Bands

Abstract: This paper presents a novel compact 2 × 2 planar MIMO antenna system with ultra-wide band capability. Antenna system is specifically designed to target lower 5th generation operating bands ranging from 2 GHz to 12 GHz. This band also covers the IEEE 802.11 a/b/g/n/ac. The antenna array geometry has been simulated using CST MWS. The design is extremely miniaturized with total structure size of mm3. The simulated and measured results have been presented. Measured and simulated return loss values for designed antenna are less than −10 dB over the operating band and lowest values of −35 dB and −32.5 dB can been seen at 5.2 GHz and 9.2 GHz, respectively, whereas at the center frequency the return loss is −25.2 dB. The mutual coupling between both elements is less than −20 dB over the transmission bandwidth. Simulated and measured radiation patterns in E and H planes at center frequency show nearly isotropic far fields. The maximum gain is measured as 4.8 dB. Promising results of Envelope Correlation Coefficient and gain diversity of the design have been achieved. Simulated and measured results are found in good agreement. The fractional bandwidth of antenna is measured as 143.2% which satisfies its ultra-wide band response.

$W$ -Band Bandpass Filter Using Micromachined Air-Cavity Resonator With Current Probes

Abstract: This letter presents a W -band micromachined air-cavity bandpass filter (BPF) using a novel integration method of a micromachined silicon air-cavity resonator with silicon pillars. With silicon pillars, which were fabricated simultaneously with a deep reactive ion etching process for forming a cavity structure, a micromachined silicon air-cavity can be easily integrated on a package substrate with a flip-chip interconnection. In this work, a thin-film substrate with a flip-chip interconnection was employed as a package substrate, in which the silicon pillars were used as the current probe between the air-cavity resonator and TFMS input/output feeding lines. With the novel integration of the air-cavity resonator, a W-band four-pole BPF has been successfully demonstrated on a thin-film substrate with a flip-chip interconnection, which exhibits a minimum insertion loss of 1.3 dB and return loss better than 16 dB with a 4.9% 3-dB fractional bandwidth at a center frequency of 93.7 GHz.

A circularly polarized dielectric resonator antenna excited by an asymmetrical U-slot with a backing cavity

Abstract: A cavity-backed circularly polarized dielectric resonator antenna (DRA) excited by an asymmetrical U-slot is investigated theoretically and experimentally. The finite-difference time-domain method using nonuniform orthogonal grids is employed to study the new configuration, with the excitation modeled by an independent resistive voltage source. The return loss, input impedance, axial ratio, and radiation pattern of the antenna are studied. Reasonable agreement between theory and experiment is obtained.