Shorting strap tunable stacked patch PIFA

An oppositely shorted dual-band stacked patch planar inverted-F antenna (PIFA) is developed. RF switches are integrated to the shorting straps of the stacked patches to make a tunable PIFA. The L band switch yields 0.45-dB insertion loss and 10-dB isolation bandwidth (BW) of 108% at 1.8 GHz. The tunable PIFA yields 10% frequency tunability BW at 745 MHz when the number of upper radiating patch's shorting straps changes and 20% BW at 1137 MHz when the number of lower radiating patch's shorting straps changes. Independent lower and upper frequency tunings are achieved through this technique.     

Compact dual-band PIFA with multi-resonators

A newly designed dual-band planar inverted-F antenna with three radiating resonators for use in mobile phone devices is presented. A high frequency structure simulator is used to verify the antenna, which operates at the GSM-900 and DCS-1800 bands. Measurements made in real-life conditions to test how the plastic case and user handing influence the performance of the device demonstrate that the bandwidths are larger than those in similar devices reported in the previous literature     

Shorting pin loaded dual-band compact rectangular microstrip antenna

Theoretical and experimental investigations carried out on shorted microstrip patch antenna for dual band operation. The investigations were carried out by varying the shorting-pin position from the edge to the centre of the patch; such an antenna provides a frequency tunability range from 0.88?GHz to 1.08?GHz for first resonance and from 2.20?GHz to 2.59?GHz for second resonance. A frequency ratio of about 2.91 to 2.2 for the two operating frequencies is observed. When the shorting-pin position is close to centre or at the centre of the patch, a single resonant frequency is observed. It is also observed that the resonant frequency of the antenna heavily depends upon the thickness of the substrate, dielectric constant of the substrate and radius of the shorting-pin.     

Wide tunable dual-band reconfigurable antenna

Presented is an antenna that allows independent and versatile dual frequency and bandwidth reconfiguration by using simple external matching circuits. Simulations suggest that the antenna has a total tuning range of 2118 MHz (from 778 to 2896 MHz) while maintaining a return loss above 6 dB. In addition, the antenna is capable of operating as a penta-band cellular phone antenna. This kind of antenna is typically required to work within the GSM900, GPS1575, GSM1800, PCS1900 and UMTS2100 bands.     

Simple tunable dual-band microstrip patch antenna

A novel technique for designing a tunable dual-band microstrip patch antenna is proposed. Dual-band operation is easily achieved by loading a microstrip patch antenna with one varactor diode placed on a small gap between a square patch and a parasitic strip. It is observed from the measured result that the proposed antenna shows a wide tuning range at the two resonant frequencies.     

一种双频电调带通滤波器的设计

提出一种新型中心频率可调谐的双频带通滤波器,该滤波器利用双端短路的阶梯阻抗谐振器(stepped-impedance resonator,SIR)结构,在其中两个不同特性阻抗传输线之间同时加载变容二极管,其输入输出结构采用50Ω的缝隙耦合馈电。采用半波长SIR的折叠型结构,实现了滤波器的小型化。并通过奇偶模的分析方法,调节变容二极管上加载的电压实现中心频率分别在1.97~2.20 GHz和4.15~4.30 GHz之间可调。比较仿真与测量结果证明了该方法有效。     

PIFA input bandwidth enhancement by changing feed plate silhouette

2.45 GHz planar inverted-F antenna (PIFA) designs mounted on a 100 mm square ground plane are examined with regard to the feed-element shape influence on the input bandwidth (BW). While the traditional wire-fed PIFA has a BW from about 4 to 12%, the novel PIFAs with diverse feed plates (triangular, bi-triangular, rectangular, rounded-rectangular and U-strip) are designs capable of a much broader BW, between 18 and 25% for some configurations.     

一种双频喇叭馈源的相位中心分析

多模圆锥喇叭天线是一种应用较广的高效率喇叭天线,它被广泛应用于反射面初级馈源。双频多模圆锥喇叭天线在收发两个频率处的相位中心是不重合的,当其作为反射面馈源时,其相位中心及安放位置的确定对于反射面天线的性能有着不可忽视的影响。从天线相位中心的定义出发,计算了双频多模喇叭天线在收发频率处的相位中心,并对该天线在偏置反射面系统中的安放位置进行了分析,确定了馈源的最佳安放位置。     

Dual-mode dual-band bandpass filter for single substrate configuration

A novel dual-mode dual-band bandpass filter (BPF) is proposed that uses a bi-interdigital coupling structure for a single substrate configuration. The BPF consists of a microstrip feed network, ground embedded slots, and outer and inner loop resonators which are excited over bi-interdigital coupled lines with tight coupling in the two passbands. The filter design, analysis via the equivalent circuit of the proposed BPF and the experimented results are dealt with.     

Microstrip dual-band bandpass filter with independently tunable passbands using varactor-tuned stub loaded resonators

In this paper, a dualband bandpass filter with independently tunable passband is proposed. Two half-wavelength resonators with shunt stub have been placed side by side, fed with a common input-output microstrip line to achieve the individual tunability without affecting other passband. For tuning resonance frequency, varactor diodes are used at the ends of the half wavelength resonators and also at the end of the shunt stubs. Proper shunt stub length and width are derived numerically in such a way that only one control voltage is required in each passband. Measured results show that lower passband can be tuned in a frequency range from 1.78 to 1.96 GHz, whereas the upper passband varies from 2.27 to 2.39 GHz individually. H shaped DGS is integrated below the input-output feed lines to suppress higher order harmonics up to 21 GHz with more than 19 dB attenuation.     

Simplified high-performance dual-band feed comprising a dual-depth corrugated launcher and a conventional corrugated horn

The design of a corrugated feed is presented which has a simplified configuration in comparison to a feed with dual-depth corrugations over its full length. It exhibits excellent electrical performance which is compatible with the requirements for frequency reuse application in satellite communication antennas. The feed consists of a short dual-depth corrugated launcher and a conventional corrugated horn. Important electrical characteristics of such a feed designated for operation in the standard bands of 4 and 6 GHz satellite communication links are presented.     

PIFA with PIL patch having bent feed line for GSM=DCS=UMTS=WiBro applications

A novel, low-profile internal planar inverted-F antenna (PIFA) with broadband characteristics is proposed for GSM/DCS/UMTS/WiBro applications. Broadband characteristics are achieved by inserting an inverted-L patch, and a bent feed line ensures good impedance matching. The optimum design parameters of the proposed antenna are decided by parametric analysis. Good omnidirectional patterns with reasonable gains are achieved at each frequency band of interest     

产生单模可调谐ps单脉冲的串联超短腔染料激光器

报道了亚nsN_2激光脉冲泵浦的两级超短腔串联和一级放大组成的染料激光器,产生单模、波长可连续调谐、脉宽可达17ps的单脉冲.讨论了放大级获得最佳增益及抑制ASE等有关问题.     

Analysis of a tunable single mode optical fiber coupler

We report the operation and the theoretical modeling of an efficient, tunable, and low-loss single mode fiber coupler. The coupler design follows a scheme previously reported, in which two optical fibers mounted in curved grooves in separate quartz substrates are polished until sufficient cladding material has been removed to permit optical coupling between the mated polished faces of the fibers. The results of a computer analysis of the distributed coupling taking place between the fibers are discussed, emphasizing the intuitive dependences of the coupling coefficient and effective interaction length of the device on its geometrical parameters. A detailed experimental analysis of fiber couplers follows in which we characterize two types of couplers made with different brands of single-mode fibers. Operation up to 100 percent coupling ratio and 50 dB extinction ratio between coupled and direct branch as well as operation in overcoupling regimes are demonstrated, both at visible and infrared signal wavelengths. Tuning curves are shown that emphasize the excellent tunability properties of such couplers in which the coupling ratio can be smoothly and continuously tuned between 0 and 100 percent. Experimental evidence of the relatively low loss level and very low polarization dependence of the fiber couplers are also presented. All experimental results, including an analysis of the influence of the refractive index of the intermediate layer of index-matching liquid between the polished faces of the fibers, are found to be very well predicted by our theoretical model.     

Broadband tunable single frequency diode-pumped erbium doped fibre laser

A single frequency erbium fibre laser with continuous wavelength tuning over the range 1525-68 nm has been demonstrated using a unidirectional loop mirror (ULM) configuration. The fibre laser is diode pumped at 1480 nm with a threshold of 9 mW, slope efficiency of 12% and has a linewidth of less than 295 kHz.<>     

The designing, manufacturing, and testing of a dual-band feed system for the Parkes radio telescope

This paper presents the designing, manufacturing, and testing of a dual-band feed system for the Parkes radio telescope (Australia). The feed system consists of a coaxial horn and associated feed components to operate in the 648-712 MHz and 2.6-3.6 GHz frequency bands. The manufacturing of such a feed system was challenging, and we present the innovative solutions that were devised to fabricate the different parts of the feed system. Preliminary measurements indicate that the overall system, feed and reflector, is working to operational expectations, and valuable scientific results have already been obtained using the simultaneous dual-frequency capability.     

New resistorless tunable voltage-mode universal filter using single VDIBA

To increase the universality of the recently introduced voltage differencing inverting buffered amplifier (VDIBA), this letter presents a new voltage-mode (VM) multi-input–single-output (MISO) universal filter. The proposed filter contains only single VDIBA, two capacitors, and one nMOS transistor, operated in triode region, and is used for resonance angular frequency tuning. Since in the structure no resistors are needed the filter can be classified as resistorless. The VM MISO filter compared with other active building block-based counterparts is very simple, it contains only few transistors, and has the smallest size area. Moreover, no component matching is required and it shows low sensitivity performance. The theoretical results are verified by SPICE simulations using TSMC 0.18 μm level-7 SCN018 CMOS process parameters with ±0.9 V supply voltages. In addition, the behavior of the proposed VM filter was also experimentally verified using commercially available integrated circuits OPA660 and AD830.     

Investigation of tunable single frequency diode lasers for sensorapplications

The coherence and tuning properties of tunable single-frequencies lasers used in coherent detection systems have been investigated. The use of a fixed external cavity was found to increase significantly the coherence length of such systems but simultaneously reduce the tunability. An essentially all-electronic phase-modulated external cavity was used to restore the tunability, and a tuning range coherence length product of ~500 GHz-m was achieved. The modulated external activity laser was used in a coherent lidar system that achieved a maximum range of 150 m and a fractional resolution of 0.5%. The system is also shown to be a powerful tool for mapping out the tuning and coherence properties of tunable single-frequency lasers     

Center feed single layer slotted waveguide array

A center feed configuration is newly introduced to enhance the bandwidth as well as to suppress the frequency dependent beam squinting in single layer slotted waveguide arrays. A multiple-way power divider consisting of cross-junctions is installed at the center of the aperture in an alternating-phase fed waveguide slot array to reduce the long line effect in the radiating waveguide. Each radiating slot is equipped with an inductive wall for reflection canceling, which dispenses with the beam tilting technique for suppressing cumulative reflection and assures the boresight beam. All these are equipped in single layer and are potential for low cost mass-production as is usual the case with alternating phase-fed arrays. The test antenna is fabricated at 26GHz band for FWA system. A 30.5 dBi gain with 46% efficiency with the main beam staying in the boresight is obtained. The sidelobes of -9.5 dB associated with the aperture blockage for the center feed is suppressed to below -14.7 dB at the design frequency, by applying a genetic algorithm for controlling the slot excitation.