The Use of Matched Four-Port Filters to Realize Switched Multiplexer Having Low Amplitude and Group Delay Ripple

A design method for channelizers and multiplexers is presented with particular emphasis on simplicity of design and alignment. By using two recombining multiplexers, one for the odd-numbered channels and one for the even-numbered channels, a high-performance switched multiplexer may be realized. The key to this perfornnance is a multiplexer based on channel filters with integral hybrids which is designed to be matched in both passband aud stopband. The design criteria for such devices are presented for filters having finite Q structures. An eight-channel switched multiplexer in S-band is described, with experimental results in close agreement with theory.     

Criteria for wide-band radial switch design

This paper presents criteria for the design of radial switches, such as can be used in electronically steered circular array antennas for satellite communications mobile terminals. The choice of the switching circuit and diode used in each channel is discussed and the required inductance for the diode shunt capacitance compensation for lower insertion loss is given. Analytical formulas are derived for the general case of an ideal transmission-line switch to show the dependence of the return-loss bandwidth on the choices of the line impedance. Important optimization criteria for lower insertion loss and increased bandwidth are drawn. The criteria have been used to guide the design of economical L-band microstrip switches for use in INMARSAT/MSAT antenna arrays, using low-cost printed-circuits and surface-mount plastic-encapsulated p-i-n diodes. Implementation results for insertion loss, reflection coefficient, and isolation between channels are reported     

一种毫米波微带带通滤波器的设计

摘要：基于小反射理论,引入Klopfenstein阻抗渐变线对传统发夹型谐振器结构进行改进,设计了一种相对带宽为8%的结构紧凑型毫米波带通滤波器。采用S参数的多项式综合方法得到耦合矩阵电路模型,利用三维电磁场全波仿真软件HFSS拟合出耦合系数与谐振器间距、外部品质因数与抽头位置的关系曲线,进而提取出耦合矩阵对应滤波器的物理尺寸。实测结果表明：在28.8GHz-31.2GHz频带内,该滤波器的插损小于3.0dB,回波优于-17dB,带外抑制大于40dB@33GHz,测试结果与计算结果吻合较好。     

Broadband, electrically long vertical waveguide interconnect

A bandwidth optimised vertical interconnect using a rectangular waveguide to couple two microstrip lines is presented. The electrically long interconnect gives low insertion loss and large bandwidth, in contrast to other indirectly and directly coupled interconnects. Experimental results show <1.5 dB insertion loss and <20 dB return loss over a wide bandwidth 8.1-0.7 GHz     

A silicon micromachined four-pole linear phase filter

A 27-GHz four-pole linear phase filter constructed of micromachined cavities in silicon is presented. The structure of the filter consists of four side-by-side horizontally oriented cavities, which are coupled in turn by evanescent waveguide sections with three direct-couplings and one cross-coupling between the first and fourth cavity resonators. The cavities are reduced-height waveguide resonators and are fed by microstrip lines through slot apertures. A time-domain tuning technique is employed to improve the efficiency of the design synthesis. The measured results are presented and compared to those predicted by a finite-element-method model. The simulated filter response has a bandwidth of 2.2% centered at 27.480 GHz with an insertion loss of 1.4 dB at that frequency. The measured performance indicates a 1.9% bandwidth centered at 27.604 GHz with a deembedded insertion loss of 1.6 dB at that frequency and a measured unloaded Q of 1465.     

A vertically integrated micromachined filter

A 10-GHz filter constructed of slot-coupled micromachined cavities in silicon is presented. The novel character of the filter lies in its structure, which consists of a microstrip feed to cavities via slot apertures and three vertically stacked slot-coupled cavities. The cavities are essentially reduced-height waveguide resonators. The measured results are presented and compared to a finite-element-method model. The simulated model has a bandwidth of 4% with an insertion loss of 0.9 dB at 10.02 GHz. The measured filter yields a 3.7% bandwidth with a deembedded insertion loss of 2.0 dB at 10.01 GHz. Various loss mechanisms are examined to explain the difference between simulated and measured insertion loss     

Modified Wilkinson Power Dividers for Millimeter-Wave Integrated Circuits

A modification of the Wilkinson power divider is presented that eases planar implementation while maintaining performance. By adding transmission lines between the resistor and the quarter-wave transformers of the traditional design, a range of valid solutions exists that meet the conditions of being reciprocal, isolated between the output ports, and matched at all ports. The proposed design is particularly useful at millimeter-wave frequencies where reduced physical dimensions make a circuit configuration suitable for low-cost package-level implementation difficult using traditional methods. Two frequency bands are demonstrated. At V-band, the circuit gives 0.3-dB excess insertion loss, 19-dB isolation, and 50% bandwidth. At the W-band, the circuit gives 0.75-dB excess insertion loss, 24-dB isolation, and 39% bandwidth.     

A Broadband Planar Magic-T Using Microstrip–Slotline Transitions

The improved version of a broadband planar magic-T using microstrip-slotline transitions is presented. The design implements a small microstrip-slotline tee junction with minimum size slotline terminations to reduce radiation loss. A multisection impedance transformation network is used to increase the operating bandwidth and minimize the parasitic coupling around the microstrip-slotline tee junction. As a result, the improved magic-T has greater bandwidth and lower phase imbalance at the sum and difference ports than the earlier magic-T design. The experimental results show that the 10-GHz magic-T provides more than 70% of 1-dB operating bandwidth with the average in-band insertion loss of less than 0.6 dB. It also has phase and amplitude imbalance of less than plusmn1deg and plusmn0.25 dB, respectively.     

Exact Synthesis of Broadband Three-Line Baluns

Three types of three-line baluns are studied in this paper. The equivalent circuits of these baluns are derived using the model of coupled transmission lines. The balun designs with Chebyshev response can then be exactly synthesized. A complete design procedure of the baluns with second-, third-, and fourth-order insertion loss functions is presented. Balun designs with wide bandwidths of more than 2 to 1 are achievable by this method. Some guidelines for practical realization are also suggested. A third-order balun design with a fractional bandwidth of 80% is given to demonstrate the proposed procedure.     

Theoretical design optimization of multiple-quantum-wellelectroabsorption waveguide modulators

Optical on-off modulators require low insertion loss, high contrast ratio (CR), small drive power and large bandwidth or bit-rate. A systematic approach to optimize the total performance of these modulators based on the quantum-confined Stark effect is presented here. The approach consists of minimizing the power/bandwidth ratio while satisfying a given CR and insertion loss. Our design consists of a large-core multimode passive waveguide with a thin buried active layer. The passive waveguide is designed to yield a high coupling efficiency to conventional single-mode fibers. The quantum well material structure is designed to maximize Δα/ΔF², while maintaining a sufficiently large Δα/α₀, where Δα is the absorption change, α₀ is the residual absorption at zero bias, and ΔF is the swing of the applied electric field. Our theoretical model shows that i) wider quantum wells give larger Δα/ΔF², and ii) the bandwidth/power ratio as high as 4 GHz/mW can be achieved simultaneously with small insertion loss, For example, with a drive voltage of 3 V, an RC limited bandwidth as high as 60 GHz is predicted, while a contrast ratio of 20 dB and a total insertion loss of 4.5 dB may also be obtained     

Design of Low-Profile Millimeter-Wave Substrate Integrated Waveguide Power Divider/Combiner

A low-profile millimeter-wave substrate integrated waveguide (SIW) power divider/combiner is presented in this paper. The simplified model of this compact SIW power dividing/combining structure has been developed. Analysis based on equivalent circuits gives the design formula for perfect power dividing/combining. In order to verify the validity of the design method, a four-way SIW power divider/combiner circuit operating at Ka band is designed, fabricated and measured. Good agreement between simulated and measured results is found for the proposed passive power divider/combiner. Experiments on the four-way passive divider/combiner back-to-back design demonstrate a minimum overall insertion loss of 1.5 dB at 31.1 GHz, corresponding to a power-combining efficiency of 84%. The measured 10-dB return loss bandwidth is demonstrated to be 2.2 GHz, and its 0.5-dB bandwidth was 2 GHz.     

Broad-Band Coupling of High-Q Resonant Loads

Considering the method of broad-band coupling a series resonant RLC load to a resistive source using a uniform quarter-wave transmission-line inverter, it is shown that the 3-dB bandwidth of the network insertion loss reckoned with respect to a 0-dB loss attains a maximum for a particular value of the center frequency insertion loss in the range 0-3 dB. The center frequency Ioss and the corresponding value of the maximum 3-dB bandwidth are calculated for various loads and the results graphically presented.     

New wide-band DC-block cymbal bandpass filter

A new low-loss dc-blocking parallel-cascaded bandpass filter is presented. The filter is much easier to use and fabricate, more compact, and simpler to design than the conventional end- or parallel-coupled line filters. The filter has a wide passband with a 2:1 voltage standing-wave ratio bandwidth of around 10% and an insertion loss of 0.5 dB at 10 GHz. Simulated results agree very well with experimental results     

A Narrow Band Dual Mode HTS Patch Filter With High Power Capability

A novel structure is presented to optimize the design of narrow band dual mode patch filters. Using this method, a narrow band dual mode high power HTS filter with center frequency 2.015 GHz, fractional bandwidth less than 0.35%, return loss greater than 20 dB, near band-edge rejection close to ${-}45$ dB, and insertion loss less than 0.2 dB has been designed and fabricated. The filter can work at a power of 11.7 W without obvious deterioration of its transmission response.      

A 60-GHz Millimeter-Wave Bandpass Filter Using 0.18-μm CMOS Technology

This letter presents the design and implementation of a 60-GHz millimeter-wave RF-integrated-circuit-on-chip bandpass filter using a 0.18-mum standard CMOS process. A planar ring resonator structure with dual-transmission zeros was adopted in the design of this CMOS filter. The die size of the chip is 1.148times1.49 mm². The investigations of sensitivity to the insertion loss and the passband bandwidth for different perturbation stub sizes are also studied. The filter has a 3-dB bandwidth of about 12 GHz at the center frequency of 64 GHz. The measured insertion loss of the passband is about 4.9 dB, and the return loss is better than 10 dB within the passband.     

一种新颖结构的宽带微带至共面带线转换器的设计

通过采用高频仿真软件IE3D Verion10.0对系统参数进行优化,设计了一种新颖结构的宽带微带至共面带线的转换器,并对其各部分结构进行了研究和比较,测得转换器在4.2GHz～18.2GHz的大频率范围内的插入损耗低于1dB,回波损耗大于10dB.     

A 50-kW CW Ferrite Circulator in S Band

A 50-kW CW differential phase-shift circulator at 2450 MHz has been developed. Its insertion loss and isolation are 0.18 dB and 20 dB, respectively, over a bandwidth of 25 MHz at 2450 MHz. It is useful for protecting the microwave source of a high-power system from reflected power. The design and experimental results of the circulator are presented.     

Resonated GaAs FET devices for microwave switching

Several designs of monolithic switches for X-band applications have been fabricated and tested. These switches, which consist of two parallel-resonated GaAs FET's in a series SPDT configuration, have very low dc power dissipation, low insertion loss, and are bidirectional. An insertion loss of 0.7 dB with 28-dB isolation at 10.2 GHz has been measured for these devices. A simple equivalent circuit model is presented which explains reasonably well the basic features of resonated GaAs FET switches. The tradeoffs between performance and bandwidth, and the important design criteria, particularly with respect to the layout of monolithic inductors, are investigated.     

32 channel WDM multiplexer with 1 nm channel spacing and 0.7 nm bandwidth

A high density WDM multiplexer capable of combining 32 channels spaced 1 nm apart onto a monomode fibre is reported. The multiplexer incorporates a microlens array to give a channel bandwidth of 0.7 nm. The wavelength range of operation is 1.5285 mu m to 1.5595 mu m, within the erbium fibre amplification range. The mean insertion loss over the 32 channels is 6.7 dB and the polarisation sensitivity is less than 0.7 dB.<>     

Temporal characteristics and scaling considerations of multimodeinterference couplers

A mode propagation model is used to analyze the temporal response of a multimode interference (MMI) coupler. The response is characterized as a function of the splitting ratio so that the effects of architectural scaling can be predicted. Results are presented for a specific coupler design. The results indicate that an increase in aggregate bandwidth, defined as the combined bandwidth of the parallel output channels of the coupler, is accompanied by a decrease in coupled power and energy. The loss in efficiency is shown to be independent of whether the increase in aggregate bandwidth is produced by an increase in the splitting ratio or the signal bandwidth