Design of a microstrip diplexer with a novel structure for WiMAX and wireless applications

In this paper, a novel combination of coupled lines, loops, step impedance and low impedance sections are used to design a compact microstrip diplexer. The designing method is based on obtaining transmission matrices and finding the effective parameters in tuning the resonance frequencies. T-shape tapped lines feed structures are added to three terminals of the proposed diplexer to decrease insertion losses at the both passbands without increasing the overall size. The proposed diplexer with a total size of 573.11 mm² operates at 2.6 GHz for IEEE 802.16 and 802.20 WiMAX technology and 6 GHz for wireless applications. The insertion losses at the lower and higher resonance frequencies are 0.6 dB and 0.9 dB, respectively. The proposed structure is simulated, fabricated and measured. The measurement results are in a good agreement with the simulations.     

Compact low-loss microstrip diplexer using novel engraved semi-patch cells for GSM and WLAN applications

This paper presents a novel microstrip diplexer constructed by integrating the engraved semi-patch cells. It operates at 1.8 GHz for global system for mobile communication (GSM) and 2.4 GHz for wireless local area network (WLAN). The introduced structure is well miniaturized so that it has a compact size of 0.022 λg². The others advantages of the proposed diplexer are the low insertion losses less than 0.16 dB, good in-band channel isolation higher than 34 dB and two wide fractional bandwidths. Moreover, 1st, 2nd and 3rd harmonics are attenuated with the maximum level of −20 dB. A harmonic attenuation method is presented based on analyzing the resonance modes. In order to verify the simulation results, the designed diplexer is fabricated and measured. The simulation and measurement results are in a good agreement.     

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 λ_g. 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.     

Compact and high-performance bandpass filter and diplexer based on SCMRC-loaded SIR

Bandpass filter (BPF) and diplexer, which are required to be compact size and high performance, are widely used in modern wireless communication systems. In this article, novel BPF and diplexer are designed using the proposed resonator called spiral compact microstrip resonator cell (SCMRC)-loaded stepped-impedance resonator (SIR). The SCMRC-loaded SIR is proposed using the slow-wave structure SCMRC to replace the low-impedance section of the conventional SIR. Compared with the conventional SIR, the new SCMRC-loaded SIR has a compacter size and can generate a transmission zero above its fundamental resonant frequency. As examples, a BPF with the central frequency at f ₀?=?1?GHz and a diplexer operating at 0.9/1.57?GHz are designed and fabricated. The fabricated BPF occupies a compact size of 0.07 λ ₀?×?0.035 λ ₀ and has a??60?dB rejection level wide stopband from 1.2 f ₀ to 3.8 f ₀. The fabricated diplexer occupies a compact size of 0.076 λ ₀?×?0.128 λ ₀ and has an up to??50?dB output isolation. Good agreement can be observed between the simulations and the measurements.     

Design of the H<Subscript>10</Subscript><Superscript>□</Superscript> to H<Subscript>01</Subscript><Superscript>°</Superscript> Sector-Type Mode Converter at Ka-Band

A design procedure for the H₁₀^□ to H₀₁^° sector-type mode converter at Ka-band is described in detail. As an example, an H₁₀^□ to H₀₁^° sector-type mode converter with an input rectangular port size as 7.112×3.556 mm² and another output circular port diameter as 17.2 mm is designed and measured for insertion losses and wanted mode pattern. The mode converting efficiency from H₁₀^□ mode to H₀₁^° mode is about 91.2%. The insertion losses of the converter are lower than 0.1525 dB with 2GHz band.     

A 3–10 GHz Ultra Wideband Receiver LNA in 0.13 \mu m CMOS

A fully integrated low-power, low-complexity ultra wideband (UWB) 3–10 GHz receiver front-end in standard 130 nm CMOS technology is proposed for UWB radar sensing applications. The receiver front-end consists of a full UWB band low-noise amplifier and an on-chip diplexer. The on-chip diplexer has a 1 dB insertion loss and provides a \(-\) 30 dB isolation. The diplexer switch was co-designed with the receiver input matching network to optimize the power matching while simultaneously achieving good noise matching performance. The receiver low-noise amplifier provides a 3–10 GHz bandwidth input matching and a power gain of 17 dB. The overall receiver front-end consumes an average power of 13 mW. The core area of the transceiver circuit is 500 \(\mu \) m by 700 \(\mu \) m.     

A fully integrated 33.8-dBm bulk CMOS T/R switch with a negative-voltage switch controller

This paper presents a single-pole double-throw CMOS transmit/receiver (T/R) switch in a standard 0.18 μm CMOS process. The T/R switch uses 6-stacked body-floated N-MOSFETs to enhance linearity, and a negative-voltage controller integrated on a single die with the power switch cell. A complementary DICSON charge pump is employed to generate the negative voltages and three-step level shifters are used to control the switch cell. The fabricated T/R switch has P_1dB of 33.8 and 32.6 dBm at 900 and 1,800 MHz from a 2 V supply, respectively. The insertion losses of TX are 0.7 and 1.1 dB at 900 and 1,800 MHz, respectively. The isolations from TX to ANT and RX to ANT are >25 dB at both frequencies, and the return losses are >20 dB. The proposed T/R switch shows comparable or better performance compared to the previously reported T/R switches without the switch controller.     

基于互补裂环谐振器的集成波导双工器设计

提出了一种基于圆形互补裂环谐振器的新型基片集成波导双工器。该款双工器工作在C波段,两个通道滤波器的工作频率均低于基片集成波导谐振腔的截止频率,由此达到小型化的目的,通道滤波器的体积较传统基片集成波导滤波器缩小约30%。圆形互补裂环谐振器较方形互补裂环谐振器的小型化效果好,并且更易设计。文中提出了一种新的增加通道隔离度方法,即在两个互补裂环谐振器之间切开一个缝隙。该款双工器已被加工成实物,实测两通道插入损耗为1.75 dB(@3.92 GHz)和1.62 dB(@4.62 GHz),隔离度＞37 dB,实测数据和仿真结果吻合。     

Max-SINR Based Timing Synchronization Scheme in Hexagonal Multicarrier Transmission

In this paper, the maximizing Signal-to-Interference-plus-Noise Ratio (Max-SINR) criterion is applied in Hexagonal Multicarrier Transmission (HMT) system for timing synchronization. An iterative approach for Max-SINR timing over doubly dispersive (DD) channel with exponential power delay profile and U-shape Doppler spectrum is proposed. Theoretical analysis shows that there is an allowable SINR gap between the mean delay of DD channel and the optimal timing point. Meanwhile, a low complexity suboptimal timing approach based on instantaneous channel frequency response is proposed. Theoretical analysis and simulation results show that Max-SINR timing scheme outperforms traditional timing method about 2–15 dB in SINR and the suboptimal timing algorithm achieves a smaller Mean Square Error than 10^?4 over DD channels. In addition, the Iterative Projection Sequence Detection (IPSD) receiver is proposed and the Match Filter Low Bound (MFLB) in HMT system is given. Simulation results show that the Bit Error Rate (BER) of the proposed IPSD approach based on iterative Max-SINR timing approximates to the MFLB and outperforms traditional timing scheme about 3dB at BER = 10^?3.     

Study of combined transmission line for high power wave generated by a gyrotron in the millimetre wavelength range

A powerful millimetre-wave line transmitting energy from a gyrotron to a tokamak is studied. The line is open and combines mirrors and sections of an irregular oversized circular waveguide. The construction of the transmission line units is improved to provide selectivity for the operating TE₀₁ mode. Particularly, the open quasioptical elbow operating at the long-wave region of the millimetre range and rotating the line by an angle of 90^° is experimentally investigated. The operating TE₀₁ mode insertion losses are 0.2-0.3 dB with a 4% bandwidth.     

Enhanced Thermoelectric Properties of (PbTe)0.88(PbS)0.12 Composites by Sb Doping

The effects of Sb doping on (PbTe)_0.88(PbS)_0.12 composites prepared by melting, ball milling, and spark plasma sintering were investigated. The x-ray diffraction results indicate that all samples Sb _x Pb_1?x Te_0.88S_0.12 with x = 0, 0.002, 0.004, 0.006 and 0.008 are composites containing PbTe with NaCl-type structure as the major phase and PbS with NaCl-type structure as the minor phase. The electrical resistivity is reduced with increasing Sb doping, from 1.95 × 10^?5 Ωm for Sb content x = 0 to 5.55 × 10^?6 Ωm for x = 0.008 at 298 K, showing that Sb is an efficient electron donor. However, the absolute Seebeck coefficient decreases, from 196 μV/K for x = 0 to 57.0 μV/K for x = 0.008 at 298 K, and the thermal conductivity increases, from 0.989 W/m K for x = 0 to 1.64 W/m K for x = 0.008, with Sb doping. The power factor and figure of merit ZT can be enhanced by proper Sb doping. The maximum dimensionless figure of merit ZT of 1.20 was obtained in the sample Sb_0.004Pb_0.996Te_0.88S_0.12 at 773 K.     

A compact and high performance dual-band bandpass filter based on unbalanced composite right/left-handed transmission lines for WLANs applications

In this paper, a novel compact microstrip dual-band (DB) bandpass filter with high selectivity for wireless local area networks applications is proposed. The design procedure is based on unbalanced composite right/left-handed (UCRLH) transmission lines (TLs). The DB features can be achieved by unbalancing the CRLH transmission line. The necessary conditions to obtain a discontinuous transition between the left- and right-handed bands, intended to provide UCRLLH TL, are investigated. The application of this technique to design of compact DB filters is illustrated. The structure of the proposed DB filter is implemented by a series interdigital capacitor located between two microstrip lines that shorted to the ground plane by vias. The vias with microstrip lines acting as a shunt connected inductor while the series capacitor is realized by interdigital capacitor. The design procedure based on a simple equivalent circuit is also introduced. The proposed filter has advantages such as compact size, easy fabrication, high selectivity, low insertion loss, high return loss and, design flexibility. To validate the proposed technique, the proposed DB filter has been fabricated and tested. Good agreement has been found between simulation and measurement results. The total size of the proposed UCRLH DB filter is 0.17 λ_g × 0.048 λ_g, where λ_g is the guided wavelength of the lower pass-band. The size of the proposed DB filter is more compact in comparison with known similar filters.     

UWB distributed amplifier design using lookup tables and g<Subscript>m</Subscript> over I<Subscript>D</Subscript> methodology

This paper introduces a synthesis procedure for designing Ultra-Wide Band (UWB) Distributed amplifiers (DA) based on lookup tables exploiting the g_m over I_D methodology. In order to validate the proposed approach, two conventional DAs with different number of stages were synthetized. The two DAs were implemented using the IHP 0.13 µm SiGe process and both achieve power gain of 11 dB, bandwidth of 10.6 GHz and DC-power consumption of 26 mW with a 1.2 supply voltage. The post-layout simulations validate both the accuracy and effectiveness of the procedure proposed for optimizing the DA performances. Additionally, the four-stage DA configuration, designed with the proposed approach achieves input/output matching return losses better than 16/18 dB. To the authors knowledge, these values are the best input/output return losses ever reported in literature for a conventional DA designed for UWB applications.     

A Rectangular SRR Switched Slotted Microstrip Patch for Frequency Diversity Application

Planar antenna with a specific resonant mode is essential to meet the diversity demand for wireless communication. This paper presents modeling and experimental validation of a microstrip antenna design in which multiple resonant frequencies are excited based on different negative permeability response of the rectangular split ring resonator (SRR). The antenna geometry consists of a slotted patch with split ring resonator loaded between its two arms. The patch was fabricated on FR-substrate of relative permittivity ε_r?=?4.4, and has a size of 30.5 mm?×?34 mm. In the antenna desing, PIN diodes connect the outer ring and inner ring resonator of the SRR to the adjacent arms of the patch. Under various bias conditions, quad-band resonance was observed at 2.07 GHz, 2.11 GHz, 2.31 GHz, and 2.46 GHz. The measured S₁₁ results are found comparable to the simulated data, and demonstrate proper functioning of the proposed antenna with stable gain and radiation patterns.     

Graphene-Based\ Waveguide Terahertz Wave Attenuator

We design an electrically controllable terahertz wave attenuator by using graphene. We show that terahertz wave can be confined and propagate on S-shaped graphene waveguide with little radiation losses, and the confined terahertz wave is further manipulated and controlled via external applied voltage bias. The simulated results show that, when chemical potential changes from 0.03 into 0.05 eV, the extinction ratio of the terahertz wave attenuator can be tuned from 1.28 to 39.42 dB. Besides the simplicity, this novel terahertz wave attenuator has advantages of small size (24?×?30 μm²), a low insertion loss, and good controllability. It has a potential application for forthcoming planar terahertz wave integrated circuit fields.     

Compact wideband bandpass filter using quad mode resonator

This paper presents a compact wideband bandpass filter for TETRA band applications. The proposed filter design is based on a quad mode resonator designed using small rectangular loop loaded with four Stepped Impedance Stubs (SISs) and a short circuit stub. The four modes of the resonator help in generating a wide passband. The use of SISs makes the filter compact. In addition to four transmission poles, the resonator inherently generates a transmission zero above the higher end of passband. Two transmission zeros are generated by the input/output coupling which helps in increasing the selectivity and also for achieving wide stopband. This filter provides a 3 dB fractional bandwidth of 30.33% and maximum insertion loss of 1.3 dB at the center frequency 0.36 GHz with a compact size of 0.125 λ_g × 0.085 λg (4.1 × 2.78 cm²).     

Diplexer Operation of Stripline Y Circulators: Part 1--Basic Performance of Diplexer Operation

The diplexer operation as another version of tbe double circulation frequency operation (DCFO) was recently performed with stripline Y-junction loaded with conductor-ferrite (CF) composites. Experimental results demonstrated that the large insertion Iosses appeared in association with higher order circulations. This paper treats circulation adjustments for basic performance of the diplexer operation. Theoretical analysis presents a criterion upon which to test circulation adjustments in getting an idea DCFO performance in the instances of the diplexer operation. Better combinations of circulating modes for the diplexer operation, and relevant circulation adjustments are discussed. It is concluded that the main cause to the large insertion Iosses insufficiency in circulation adjustments. Experimental results are also presented. In this paper, phenomenological explanation of various circulations is given in preparation for subsequent treatment of the diplexer operation. All ferrites used are treated above resonance.     

A high-performance integrated K-band diplexer

This paper describes the design and measurement of a planar diplexer integrated on a single silicon substrate. The diplexer channels are 5% and 6.5% relative bandwidth at 28 and 31 GHz, respectively. The diplexer is based on a micropackaged membrane supported capacitively coupled microstrip structure and is 1.5 cm×1.6 cm and only 1.4 mm thick. The measured insertion loss is 1.4 dB (5%) and 0.9 dB (6.5%) for the two channels with better than 35 dB isolation in the 28 GHz band and better than 50 dB isolation in the 31 GHz band. The measured results include all transition and packaging effects. The diplexer has coplanar-waveguide ports and can easily be integrated with other elements such as planar antennas, low-noise amplifier, and power amplifiers     

Miniaturized dielectric waveguide filters

Design techniques for a new class of integrated monolithic high-permittivity ceramic waveguide filters are presented. These filters enable a size reduction of 50% compared to air-filled transverse electromagnetic filters with the same unloaded Q-factor. Designs for Chebyshev and asymmetric generalised Chebyshev filter and a diplexer are presented with experimental results for an 1800 MHz Chebyshev filter and a 1700 MHz generalised Chebyshev filter showing excellent agreement with theory.     

Taper transmission line UWB Wilkinson power divider analysis and design

This paper proposed, analysed and fabricated an ultra-wideband Wilkinson power divider. This proposed power divider contains two parts, namely the transmission lines with fixed characteristic impedance and the tapered transmission line.

The power divider has a fixed architecture with the ability to broaden for different bandwidths by changing its circuit parameters including resistors and impedances. It also can create a bandwidth of about 40 GHz with a smaller physical dimension and fewer numbers of resistors.

The proposed power divider is investigated using the even/odd analysis method in order to compute equations required for designing power divider.

The proposed power divider was designed and fabricated for the 3-11 GHz ultra-wideband range. Then, the results are compared with the simulated results and a good agreement is obtained consequently. Furthermore, input return loss better than 12dB, output return loss better than 15dB, insertion loss better than 4.8dB and output ports isolation less than 12 dB are achieved by measured results. The overall size of the proposed power divider is 14.2 × 4.8 mm².