High Return Loss Research Articles

Enhancement in RMPA Parameters by Meta Material High Frequency Using at 6.65 GHz

A Rectangular micro strip patch antenna loaded with “Enhancement in RMPA parameters by Rhombus Cut Shaped Meta material high frequency using at 6.65GHz” As a rectangular microstrip patch antenna is designed at a height of 1.6mm & Left handed Meta material structure is designed at a height of 3.2mm from the ground plane by using CST-MWS software. The resonance frequency 6.65GHz of the designed antenna is using as a high frequency. We knew that frequency is increases as a bandwidth is also increases. Therefore in this paper work used at high frequency. The 10 dB impedance bandwidth of proposed antenna is 438.4MHz. The Return loss of the proposed antenna reduced to -34dB. This antenna is small size, cheap, compact and easy to fabricate, and achieve good radiation characteristics with higher return loss.

A new quad-band Wilkinson power divider

In this paper, a new quad-band Wilkinson power divider (WPD) is proposed and designed with an analytical method. A quad-band impedance transformer built up by three transmission lines and two loaded shorted-stubs is firstly proposed. The related design equations are deduced by matrix transformation. With proper assumption, a simple analytical design method is presented for the quad-band WPD, and the derived equations and plotted curves can be used for the design. The designed quad-band WPD is an equal power division structure and only one surface-mounted resistor is needed. It has been demonstrated that our proposed WPD possesses simple configuration, small size, low cost, and good performance, i.e. high isolation, low insertion, and return losses, for the quad bands simultaneously from the simulated and measured results.

A Non-Contact Submillimeter-Wave $S$-Parameters Measurement Technique for Multiport Micromachined Devices

This paper presents a novel non-contact broadband on-wafer S-parameter measurement technique for submillimeter-wave and terahertz applications. The proposed method enables S-parameters measurement of multi-port micromachined devices using a two-port measurement setup. In this method, a small fraction of the signal at each waveguide port is weakly coupled to free space using a small array of reflection-canceling slots which are then measured by an open-ended waveguide probe. The S-parameters of the device-under-test are calculated from the measured signals obtained from each port and from that of a reference match waveguide. A broadband waveguide slot array antenna with high return loss is designed as a matched load to terminate all ports of the device except the input port. To assess the reliability and accuracy of the proposed measurement method, three different micromachined waveguide directional couplers are designed, fabricated, and tested. Multiple apertures on the common wall between the adjacent waveguides are designed and optimized to achieve high directivity couplers over a broad frequency range. The measured S-parameters of the couplers are shown to be in good agreement with the simulations, which indicates the accuracy of the proposed measurement method.

Miniaturised multiband two‐element coaxial continuous transverse stub antenna for satellite C‐band applications

The continuous transverse stub (CTS) technology incorporates the use of coaxial lines to produce effective microwave antenna structures that radiate an omnidirectional pattern with high efficiency and low return loss. In this paper a two-element coaxial CTS antenna array is designed to operate in the C-band with improved efficiency and gain. The proposed prototype of the C-band antenna, with design operating frequencies –5.18, 6.536 and 7.42 GHz, finds numerous applications in C-band satellite communications. During simulation, the efficiency at these frequencies had been observed to be 89.5, 87.6 and 95.9% and their corresponding gains were observed to be 7.54, 5.24 and 7.51 dB, respectively. The measured results of the C-band antenna prototype for the above stated frequencies were observed to be 5.185, 6.845 and 7.313 GHz, respectively. This antenna can be used in INSAT/super extended C-band, fixed-satellite services which include space to earth, earth to space as well as mobile satellite services. The radiation of the designed structure is omnidirectional in the horizon plane, with minimum return loss. These simple and low-cost coaxial CTS structures can be adopted in wireless communication systems.

Compact microstrip lowpass filter with sharp roll‐off using radial resonator

A compact microstrip lowpass filter (LPF) with sharp roll-off is presented. The proposed filter consists of radial resonator, triangular patch and open stub. The proposed filter has good specifications such as low insertion loss <0.1 dB, high return loss of −20 dB, wide stopband from 4.37 to 19 GHz with −20 dB attenuation level and compact size. The LPF filter has a cut-off frequency of 3 dB at 4.24 GHz and a high roll-off rate of 130.7 and finally a high figure-of-merit of 23526.

A Dual-Band Bandpass Filter Using Coupled Semi-circular Stepped Impedance Resonators with Sharp Roll-off and Wide Stopband

In this paper, a dual-band bandpass filter using three-pole Chebyshev filter based on the semi-circular tri-section stepped impedance resonators (SIRs) loaded by trapezoidal stub is presented. The first passband is adjusted by the proper ratios of the tri-section SIR. By optimizing the resonator and inserting the trapezoidal stub, undesirable response is suppressed and the second passband is adjusted at the desired frequency. The proposed filter has low insertion losses, high return losses, good 3 dB bandwidths and sharp roll-off rates in two passbands and wide and high rejection in the stopband. There is a good agreement between the simulated and measured results.

Analysis of Effect of Conductor Line on Folded Type Meander-Line Antenna

In this paper folded type meander line antennas have been proposed. Performance of three different meander line antennas have been investigated, first one without conductor line and the other two with conductor line. First antenna is a triple band resonator while second antenna with conductor line becomes tetra band resonator and the last design is a dual band resonator but with higher return loss, -35 dB at 1.86 GHz. CST_STUDIO_2012 is being used for simulation. Far-field response, efficiency, gain, directivity and reflection coefficients have been chosen as factors for performance analysis and it has been successfully illustrated here that insertion of conductor line makes the antenna a better resonator and also improves the return loss. The proposed antennas in this paper work are able to operate in the LTE700, LTE/GSM1800, PCS/ UMTS/ WLAN/ LTE2400, L band (1-2 GHz) and S band (2-4 GHz).

Design of Microstrip LPF with Sharp Cut-off Frequency and Wide Stopband

AbstractA novel lowpass filter with wide stopband and sharp skirt characteristics is proposed. To obtain the applicable lowpass filter, several cells of coupled T-shaped resonator, U-shape and dumbbell-shaped resonators are connected in series. The proposed filter has low insertion loss, high return loss in the passband and wide stopband. The transition band is from 3.18 to 3.29 GHz with −3 and −20 dB, respectively. Results of the fabricated filter exhibit a roll-off and relative stopband bandwidth of 217 and 137%, respectively. Measurement and simulation results show good agreement.

A Tentative Analysis of the Rectangular Horizontal-slot Microstrip Antenna

In this paper, we have presented a new type of microstrip antenna mentioned as rectangular horizontal-slot patch antenna. Our main motto is to design a novel antenna which has the simplicity in structure and higher return loss. We have followed a tentative approach which leads us to an exceptional result, better than conventional one and the experimental outcomes result some guidelines for further practice. Here all of these antennas were analyzed by using GEMS (General Electro-Magnetic Solver) commercial software from 2COMU (Computer and Communication Unlimited)

拉锥光纤端面耦合效率的研究

光纤端面形状对光纤耦合的相关指标影响较大。光纤传输系统的速率越高，反射光对系统的影响越大。反射光会沿着光纤反馈到系统的激光器光源中，引起系统的不稳定和噪声，使得光纤系统的传输信息不可靠。因此我们提出通过拉锥将光纤端面制成曲面，而锥体曲面与光纤系统匹配，可以与光纤线路进行低损耗连接，具有极低的后向反射，得到更高的回波损耗。基于光纤熔接机的熔接功能，在放电熔融时使夹具反向移动，使光纤在熔融状态下获得径向拉力，可以改变光纤径向尺寸分布，光纤平端面可形成具有一定锥体的曲面。本文测量了不同放电时间和放电强度条件下，相应形成的光纤端面的插入损耗和回波损耗值，并与光纤平端面对比, 得到回波损耗可达到36 dB，并通过测试和分析，我们首次提出插入损耗随耦合端面距离改变的变化规律的结论。The shape of fiber end has a relatively vital effect on related indices of fiber coupling. The higher the fiber transmission system is, the greater the effect of reflected light is on the system. The reflected light can feed back into the laser source, causing instability and noise of system, which leads to unreliable transmission information. Then we put forward the idea that the end face can be made into curved surface by tapering to match with fiber system and be connected with low loss which has extremely low back reflection and gets higher return loss. On the basis of fusion function of fiber fusion splicer, the fixture moves reversely in the melt when it discharges and the fiber obtains radial tension in the molten state that can change the fiber radial size distribution. Then fiber end face can form a curved surface with a certain cone. In this paper we measure return loss and insert loss of fiber end faces respectively corresponding to different discharge time and intensity. In comparison with fiber flat end, we conclude that return loss of tapered fiber can reach 36 dB and to our knowledge, we first time put forward the rule that insert loss changes when the coupling end distance changes.

Compact microstrip lowpass filter with wide stopband and sharp roll-off using tapered resonator

In this article, a novel microstrip lowpass filter (LPF) with specifications such as sharp cut-off, wide stopband, low insertion loss and high return loss using tapered resonator is presented. The LPF has cut-off frequency of 1.11 GHz, where unwanted harmonics are suppressed by novel tapered cells. The bandwidth is enhanced, and the size is reduced as compared to the conventional tapered filter. The transition band is approximately 0.29 GHz from 1.11 to 1.4 GHz with corresponding attenuation levels of –3 and –20 dB, respectively. The stopband with greater than –20 dB rejection is from 1.4 to 8.9 GHz, insertion loss in the passband is less than 0.1 dB, return loss is less than –18 dB and the overall size of the filter is 0.12 × 0.073 λg. The proposed filter is fabricated and measured. The simulation and measurement results are in good agreement. This LPF is designed for microwave communication applications, especially wireless video transmitters.

A Compact Dual‐Mode Dual‐Band Bandpass Filter Using Stepped‐Impedance Open‐Loop Resonators and Center‐Loaded Resonators

ABSTRACTIn this article, a compact dual‐mode dual‐band bandpass filter is proposed by using two modified stepped‐impedance open‐loop resonators and center‐loaded bars. The dual‐mode resonators are created by loading two center‐loaded bars, and this process is investigated through dual‐mode filter analysis. The external quality factor and the coupling coefficient is introduced and analyzed to optimize the proposed filter. A low insertion loss and high return loss dual‐mode dual‐band filter is designed and fabricated with a compact structure. Three transmission zeros are created near the passband, leading to a high selectivity. Two passbands are centered at 3.88 and 5.35 GHz with an insertion loss of −0.38 and −1.03 dB, respectively, and 3‐dB fractional bandwidths of 12.4 and 8.6% are obtained. The measured return loss is higher than −24.28 and −19.33 dB at the two resonant frequencies, respectively. The simulated and measured results are in good agreement, which verifies the design methodology. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:3000–3005, 2013

A Novel Temperature Compensated Amplifier

A novel configuration for a novel temperature compensated amplifier is presented in this paper. This amplifier exhibits high performance including Return Loss is well blew-12dB from DC to 6GHz, At 3.1GHz, the typical gain is 14.1dB, noise figure is 3.0dB, 1dB compression point is 13.9dBm.with insensitivity to temperature.

Fiber-handling robot and optical connection mechanisms for automatic cross-connection of multiple optical connectors

Conventionally, in intelligent buildings in a metropolitan area network and in small-scale facilities in the optical access network, optical connectors are joined manually using an optical connection board and a patch panel. In this manual connection approach, mistakes occur due to discrepancies between the actual physical settings of the connections and their management because these processes are independent. Moreover, manual cross-connection is time-consuming and expensive because maintenance personnel must be dispatched to remote places to correct mistakes. We have developed a fiber-handling robot and optical connection mechanisms for automatic cross-connection of multiple optical connectors, which are the key elements of automatic optical fiber cross-connect equipment. We evaluate the performance of the equipment, such as its optical characteristics and environmental specifications. We also devise new optical connection mechanisms that enable the automated optical fiber cross-connect module to handle and connect angled physical contact (APC) optical connector plugs. We evaluate the performance of the equipment, such as its optical characteristics. The evaluation results confirm that the automated optical fiber cross-connect equipment can connect APC connectors with low loss and high return loss, indicating that the automated optical fiber cross-connect equipment is suitable for practical use in intelligent buildings and optical access networks.

Through-glass copper via using the glass reflow and seedless electroplating processes for wafer-level RF MEMS packaging

We present a novel method for the fabrication of void-free copper-filled through-glass-vias (TGVs), and their application to the wafer-level radio frequency microelectromechanical systems (RF MEMS) packaging scheme. By using the glass reflow process with a patterned silicon mold, a vertical TGV with smooth sidewall and fine pitch could be achieved. Bottom-up void-free filling of the TGV is successfully demonstrated through the seedless copper electroplating process. In addition, the proposed process allows wafer-level packaging with glass cap encapsulation using the anodic bonding process, since the reflowed glass interposer is only formed in the device area surrounded with silicon substrate. A simple coplanar waveguide (CPW) line was employed as the packaged device to evaluate the electrical characteristics and thermo-mechanical reliability of the proposed packaging structure. The fabricated packaging structure showed a low insertion loss of 0.116 dB and a high return loss of 35.537 dB at 20 GHz, which were measured through the whole electrical path, including the CPW line, TGVs and contact pads. An insertion loss lower than 0.1 dB and a return loss higher than 30 dB could be achieved at frequencies of up to 15 GHz, and the resistance of the single copper via was measured to be 36 mΩ. Furthermore, the thermo-mechanical reliability of the proposed packaging structure was also verified through thermal shock and pressure cooker test.

코르게이트 도파관을 사용한 위성통신용 저역통과 여파기의 설계

In this paper, low pass filters(LPF) using corrugated waveguide for satellite communication is proposed. To design the proposed LPF, the corrugated waveguide and impedance transformers are combined. The corrugated waveguide is formed by arrangement of T-junction. To obtain low insertion loss and high isolation propriety, T-junction is designed by using Chebyshev function. Impedance transformers is designed by combining T-junction with different heights at both ends of the corrugated waveguide to get high return loss. The measured results of the proposed LPF have a return loss of over 35.4 dB, a insertion loss of less than 0.1 dB from 12.25 GHz to 12.75 GHz and a isolation propriety of over 54.5 dB from 14 GHz to 14.5 GHz. From these results, it is confirmed that the proposed waveguide LPF can be used for satellite communication.

Novel splicing technique for coated optical fiber connection without stripping or cleaning process

We propose a new splicing technique by precisely aligning and directly connecting coated fibers with a capillary. The assembled splice for 1.3-μm single-mode fibers with an 80 μm cladding and a 125 μm coating can provide a low insertion loss of 0.2 dB and a high return loss of over 46 dB. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1453–1456, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27636

Performance Enhancement of Adaptive Acoustic Echo Canceller Using a New Time Varying Step Size LMS Algorithm (NVSSLMS)

This paper presents a new method for variable step size for LMS algorithm. The proposed algorithm is based on an absolute mean of estimation current and prior error vector. It is called New Varying Step Size LMS Algorithm (NVSSLMS). The main goal of this algorithm is performance enhancement of adaptive echo cancellation system. The proposed time varying step size method begins the learning process with high learning rate value ( µ MAX ) and then , it decays in an exponential profile to its minimum value (µMIN ) .The proposed algorithm is tested with real speech input signal and the result shows that it has fast convergence time, low level of misadjustment , and high Echo Return Loss Enhancement (ERLE) compared with LMS and other Variable Step Size LMS algorithm (VSSLMS) which proposed by R.H. Kwong and E.W. Johnston under similar conditions. The amount of ERLE enhancement using proposed algorithm compared with LMS and VSSLMS algorithms is about 10 dB and 8 dB respectively

Compact Microstrip Low-pass Filter with Wide Stop-band and Sharp Roll-off

This paper presents a novel compact microstrip low-pass filter with wide stop-band and sharp roll-off. The structure consists of a transmission line, loaded with coupled novel Hairpin units. The cut-off frequency of the proposed filter is 2.9 GHz. The measured results show good LPF performance such as sharp roll-off skirt, low insertion-loss, high return-loss in the pass-band and wide upper stop-band of 3.2 to 16.1 GHz with an insertion-loss higher than 20.0 dB. The measured values and the EM-simulation results are in good agreement.

A novel compact UWB BPF with independently controllable double notched bands and super wide upper stopband

This paper presents a novel compact ultra-wideband bandpass filter without and with single or multiple notched bands with significant improvements in size reduction and upper stopband enhancement in comparison with its classical counterparts. A new multiple-mode resonator capable of producing multiple transmission zeros is exploited in the filter structure to produce notch bands and improve performance of the upper stopband. A parallel-coupled structure with tapped-line input/output is applied to significantly improve the selectivity and out-of-band rejection. The proposed filter achieves outstanding electrical performance, with wide passband from 2.93 to 10.64 GHz, two notched bands centered at 5.68 and 8 GHz with rejection level better than 40 dB, low insertion loss, high passband return loss, and wide stopband with suppression level better than −25 dB up to 30 GHz. These attractive features make the proposed filter a viable candidate for any number of broadband wireless communications and radar systems.