A Dual-Band Dipole Antenna With Integrated-Balun

The design and realization of a dual-band balun-integrated dipole antenna is presented. A new type of dual-band balun is introduced as the feeding network, providing antiphase input signals for the dual-band dipole antenna. The dual-band balun is realized by the aid of a stepped-impedance transformer and tapped open-ended stubs. Combined with this balun, a uni-planar dual-band dipole antenna is designed. An experimental prototype working at 2.45/5.25 GHz are fabricated and measured. The measured performances of the antenna show good return loss and radiation patterns at the two working frequencies, proving the dual-band operation of the proposed dipole antenna.     

Dual-Band, Unequal Length Branch-Line Coupler With Center-Tapped Stubs

A new dual-band branch-line coupler scheme is proposed based on the unequal length branch-line coupler structure and the center-tapped stub lines. The unequal length structure reduces the size of the dual-band branch-line coupler using center tapped stubs. Also, it offers the possibility of the stubless dual-band operation for some special cases, and the same phase relation can be obtained between the two output signals at the two frequency bands.     

基于多模谐振加载支节的小型化双通带滤波器设计

使用多模谐振的加载支节设计了一种小型化双频滤波器。多模谐振加载支节由三条开路支节并联组成,通过调整这三根支节的长度,其前两个谐振模式可调整到一个频段内,而后两个谐振模式可以设计到另外的频段上,从而实现高隔离度的小型化双频滤波器。仿真与实测结果验证了上述设计思路。     

A UWB Bandpass Filter With Two Transmission Zeros Using a Single Stub With CMRC

A compact bandpass filter is proposed for lower-band ultra-wideband applications. It entails the design concept of a stub-tapped half-wavelength line resonator which provides three transmission poles in the passband and two transmission zeros at the high and low rejection bands. The two stubs are replaced by a single dual-band stub and the parallel coupled-line structures are meandered, leading to a compact size of 0.26lambda_g by 0.32lambda _g     

A Microstrip Fed Patch Antenna with Two Parasitic Invert L Stubs for Dual-Band WLAN Applications

A novel microstrip fed dual-band design patch antenna with two parasitic invert L stubs for 2.4/5- GHz wireless applications is presented in this paper. Printed on a dielectric substrate of FR4 with relative permittivity of 4.4 and thickness of 1 mm, and fed by a 50Ω microstrip line, the patch antenna with two parasitic invert L stubs is demonstrated to generate three resonant modes to cover 2.4/5.2/5.8- GHz wireless local area network (WLAN) bands with satisfactory radiation characteristics. Experimental and simulated S parameters are presented. Parameters sweep and simulated radiation patterns are demonstrated.     

Asymmetric Dual-Passband Coplanar Waveguide Filters Using Periodic Composite Right/Left-Handed and Quarter-Wavelength Stubs

A novel dual-passband coplanar waveguide (CPW) filter periodically loaded with the composite right/left-handed (CRLH) short-circuited stubs and the quarter-wavelength open-circuited stubs in asymmetric configuration is presented. The unit-cell equivalent circuit of the periodic structure in conjunction with Floquet's theorem is employed to find the propagation characteristics of passband and stopband regions. Unlike the conventional quarter-wavelength transmission-line inverter suitable only for a narrow frequency range, the dual-band inverter is adopted in the dual-passband filter to achieve a better frequency response within two operating bands. The performance of the 2.4/5.8-GHz third-order CRLH CPW dual-passband filter with 52% and 23% bandwidths is measured and validated by full-wave simulation. Two arbitrary passband regions are presented and the stopband within the passbands can be controlled by varying the length of open-circuited stub, supporting the flexibility and compactness of the proposed dual-passband filter     

Reconfigurable dual-band circularly polarized microstrip patch antenna for wireless applications

A new design of reconfigurable single-feed circular patch microstrip antenna for dual-band circular polarization application is proposed. The dual-band functionality is realized through incorporating cross-slots of equal slot length in the circular patch and utilizing two PIN diodes to switch the slots on or off. A pairs of tuning stubs are used to tune the circular polarization performance. The design process is presented and good results were obtained.     

Compact microstrip bandpass filter with two transmission zeros using a stub-tapped half-wavelength line resonator

A compact microstrip bandpass filter is developed using a half-wavelength (/spl lambda//2) transmission line resonator with a pair of tap-connected open-ended stubs. Such paired stubs with total length of about /spl lambda//2 constructs an equivalent line resonator. Together with two separated /spl lambda//4 line resonators, the three transmission poles can be achieved inside the passband. Meanwhile, two stub lengths are adjusted slightly longer and shorter than /spl lambda//4 to realize the two transmission zeros at both low and high rejection bands. Further, the long tapped-stub is kept wider than its short counterpart to improve the low rejection behavior. A filter sample is designed and fabricated to provide an experimental verification on the proposed filter.     

Dual-band filter using composite microstrip/CPW structure

A novel and compact dual-band filter using a microstrip/coplanar waveguide (CPW) composite structure is proposed. At the bottom of the substrate material, two CPW open-circuited resonators are broadside-coupled to the top microstrip open-circuited stubs. The proposed filter was designed, fabricated and measured. The obtained frequency responses demonstrated that the filter has good dual-band property.     

A Dual-Band Wilkinson Power Divider

A new scheme is proposed for the dual-band operation of the Wilkinson power divider/combiner. The dual band operation is achieved by attaching two central transmission line stubs to the conventional Wilkinson divider. It has simple structure and is suitable for distributed circuit implementation.     

Narrow bandpass filters using dual-behavior resonators

This paper reports on a new concept of narrow bandpass filters leading to perfectly controlled electrical responses within both the required operating bandwidth and adjacent undesired bands. A specific topology is considered for such a "global synthesis": in comparison with conventional filter performances, it provides significant improvements in terms of rejection control. The attenuated frequencies are each located apart from the bandpass frequencies and controlled by means of n transmission zeros introduced through original dual-behavior resonators (DBRs). These resonators are based on the association of different parallel open-ended stubs and allow the designer to independently control the in-band and out-of-band responses of the filter. A global synthesis approach is also discussed on a simplified architecture based on stepped impedance stubs, and the experimental results shown clearly validate the proposed concept. This simplification reduces the number of degrees of freedom when designing a DBR, and consequently the two transmission zeros become dependent.     

Design of dual-band slot antenna with double T-match stubs

A simple and compact design of dual-band slot antenna is presented. Fed by a CPW, the antenna is printed on a single-layer PCB with extremely low manufacturing cost. A pair of T-match stubs is employed to generate the dual resonances in the 2.4-2.5 and 5-6 GHz bands. The antenna of small radiating area 11/spl times/28 mm/sup 2/ is demonstrated on an FR4 PCB with ground plane size of 31/spl times/35 mm/sup 2/. Robust radiation performances are achieved, including in-band gain flatness within +/- 0.5 dB and polarisation isolation better than 15 dB. Consistent radiation patterns for both bands are obtained with peak gains about 3 and 4 dBi in the lower and upper bands, respectively.     

Switchable dual-band circularly polarised patch antenna with singlefeed

A novel patch antenna with switchable slots is proposed for dual-band circularly polarised (CP) operation. Two diode controlled slots are incorporated into the patch for dual-band operation and a pair of tuning stubs are utilised to tune the CP performance. The antenna design and experimental results are presented     

Microstrip bandpass filters using coupled feed lines for third and fourth generation communications

In this paper, two compact tuneable bandpass filters (BPFs) based on the coupled feed lines are introduced. To approach a compact size, the coupled feed lines are bended. To design a high performance single-band bandpass filter (BPF), coupled feed lines are loaded by T-shaped stubs (as main resonators) and rectangular stubs (as suppressor stubs). Also, the mechanism of coupled feed lines combining with T-shaped open stubs is analyzed to show a tunable passband. The dual-band BPF includes two big radial-stubs, two small radial-stubs, two T-shaped structures and spiral coupled feed lines. The LC model of big radial-stubs is analyzed to compute the equation of transmission zero using its transfer function. The passband frequency of single-band BPF resonates at 2.12 GHz (3G) with corresponded insertion loss of 0.83 dB. Also, for dual-band BPF, the measured insertion-losses of first and second passbands are close to 0.8 and 1.1 dB, respectively. The frequency responses of BPFs are easily adjusted by altering the physical dimensions, demonstrating a adjustable performance. To verify the correct operation of circuits, the proffered filters are implemented and tested.     

Novel Balanced Dual-Band Bandpass Filter Using Coupled Stepped-Impedance Resonators

A novel balanced dual-band bandpass filter, using coupled stepped-impedance resonators (SIRs), is proposed in this letter. The differential- and common-mode equivalent half circuits are given. By properly designing the resonators, associated with the filter composed of eight SIRs, dual-band differential-mode bandpass response can be obtained. To improve the common-mode suppression level, two open stubs with different lengths are added to the connection point of two resonators. A prototype balanced filter operating at 2.4 and 5 GHz has been realized to validate the proposed concept and theory.      

Design of Dual-Band Bandpass Filters Using Stub-Loaded Open-Loop Resonators

In this paper, open-loop resonators loaded by shunt open stubs are proposed to design compact dual-band bandpass filters with improved out-of-band rejection characteristics. The second passband of the dual-band filter is obtained by tuning higher resonant modes of the open-loop resonator by the stub length and position. A tapped-line input/output feed structure is used for external coupling. Required external coupling is obtained by adjusting the tapping position and dimension of the stub-loaded resonator. A lossless transmission line model is used to determine the resonance properties of the resonator and the external quality factor. Theoretical predictions are verified by the experimental results of three dual-band filters.     

Synthesis of dual-band bandpass filters using successive frequency transformations and circuit conversions

A novel method is proposed to synthesize dual-band bandpass filters (BPFs) from a prototype low-pass filter. By implementing successive frequency transformations and circuit conversions, a new filter topology is obtained which consists of only admittance inverters and series resonators, and is thereby easy to be realized by using conventional distributed elements. A dual-band BPF with center frequencies of 1.8GHz and 2.4GHz is designed and fabricated using microstrip lines and stubs. The simulated and measured results show a good agreement and validate the proposed theory.     

小型双频E形缝隙手机天线

提出了一种小型的双频E形缝隙手机天线。E形缝隙采用终端开路结构,并雕刻在地板的顶部,使天线的结构更紧凑,减小了天线的尺寸。同时,E形缝隙天线增加了天线的谐振路径,能产生双频宽频带特性,高低频带宽能覆盖GSM900/1800/1900/DCS/PCS/BuleTooth/UMTS/WLAN2400/WiMAX 2600通信频段。实测和仿真的结果基本吻合,验证了这种设计方法的有效性。     

基于特定相移匹配的连续类双频Doherty放大器

为了实现Doherty功率放大器在双频模式下的宽带高效工作,设计了一种基于特定相移匹配的连续类双频Doherty放大器。利用相移周期重复性原理,通过确定两个目标频段上所需要的特定相移,结合连续类放大器技术,对匹配网络进行设计,解决了传统双频Doherty放大器带宽受限的问题。设计和实现了一个2.2~2.7 GHz和3.1~3.4 GHz的双频Doherty放大器。测试结果表明,该功率放大器两个频段的饱和效率分别为64.1%~68%和60.1%~66.3%,6 dB回退效率分别达到了45.2%~52.1%和44.1%~48.5%,能满足未来移动通信系统多频段同时工作的需求。     

Dual-band toroidal beam antenna for WLAN communications

A novel dual-band toroidal beam antenna for wireless local area network (WLAN) communications is presented. The antenna mainly consists of six dual-band inverted-L radiating elements and a twosection six-way microstrip power divider. By inserting slots into the radiating elements, two resonant frequencies are achieved at WLAN bands. By using the two-section six-way power divider, the six radiating elements are excited with equal amplitude and phase at the two working frequency bands. A prototype has been constructed and tested. Good toroidal beam radiation patterns for 2.4 and 5.2 GHz bands are obtained.