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1.
    
In this article, the design of a broadband branch‐line coupler (BLC) with reduced size and suppressed harmonic passband response is presented. The proposed approach can be used to replace the low impedance λ/4 lines of the conventional BLC by an equivalent structure almost λ/12 in length. The main advantage of the proposed BLC is that, it has approximately the same bandwidth as that of a conventional BLC. A prototype broadband coupler having fractional bandwidth >50% at 1.1 GHz and of size less than one third of a conventional three‐section wideband BLC topology is realized. In addition, at least 20 dB suppression of up to fourth harmonics is achieved. © 2010 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2011.  相似文献   

2.
    
This paper presents the analysis, design, and performance characteristics of a new planar balun structure. The design is based on the log‐periodic antenna theory. The design guidelines, as well as simulation and measured results, are presented. It is shown that the new balun has greater than one octave bandwidth. A comparison to the half‐wave balun is also included. The log‐periodic balun will find applications in wireless communication circuits or devices such as mixers, amplifiers, and antennas. © 2001 John Wiley & Sons, Inc. Int J RF and Microwave CAE 11: 343–353, 2001.  相似文献   

3.
    
The wideband bandpass filtering branch‐line balun with high isolation is presented in this paper. The proposed balun can be designed for wideband performances by choosing a proper characteristics impedance of input vertical transmission line and odd‐mode impedance of parallel‐coupled lines. The proposed balun was designed at a center frequency (f0) of 3.5 GHz for validation. The measured results are in good agreement with the simulations. The measured power divisions are ?3.31 dB and ?3.24 dB at f0 and ?3 ± 0.17 dB within the bandwidth of 0.95 GHz (3 GHz to 3.95 GHz). The input return loss of 24.09 is measured at f0 and higher than 20 dB over the same bandwidth. Moreover, the measured output losses are better than 11 dB within a wide bandwidth. The isolation between output ports is 20.32 dB at f0 and higher than 13.2 dB for a broad bandwidth from 1 GHz to 10 GHz. The phase difference and magnitude imbalance between two output ports are 180° ± 4.5° and ± 0.95 dB, respectively, for the bandwidth of 0.95 GHz.  相似文献   

4.
    
A novel compact balun‐diplexer applying new interdigital line resonators (ILRs) is presented in this article. It is found that the proposed ILR can not only reduce circuit size and but also realize high common mode rejection in differential mode operation frequency. By properly converting the symmetric four‐port balanced bandpass filter (BPF) to a three‐port device, a balun BPF with high selectivity and compact size are accomplished using ILRs. Then, the balun‐diplexer can be realized by combining two well‐designed balun filters with two 50 Ω transmission lines. The demonstrated balun‐diplexer with operation at 1.8 and 2.45 GHz have been designed, fabricated, and measured. Excellent performances have been observed. Specifically, 0.4 dB in‐band amplitude error, 1.8 in‐band phase error, more than 50 dB selectivity and 45 dB isolation are obtained. © 2014 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:485–489, 2015.  相似文献   

5.
    
This article proposes an analytical design methodology for dual‐band hybrid couplers and baluns structures for any arbitrary frequency ratio using a stub‐loaded transmission line. An analysis of changing the impedance behavior of the stub, is carried out for the two bands of operation, which along with a dispersive analysis, emphasizes certain conditions where the existing methodology is not applicable. In addition, an extra degree of freedom has been included to increase the solutions for a given frequency ratio, thus providing greater flexibility and feasibility of the proposed structure. The design methodology is experimentally validated with the design and fabrication of dual‐band branch‐line and rat‐race couplers for various commercial frequency bands. © 2011 Wiley Periodicals, Inc. Int J RF and Microwave CAE , 2011.  相似文献   

6.
    
This work discusses simulation‐driven design of miniaturized wideband branch‐line couplers with a variable topology. Size reduction is enabled here by replacing uniform transmission lines of the original coupler with slow‐wave structures in the form of cascaded compact cells and meander lines. The primary goal is to determine a number of cells in the cascade and particular cell dimensions for which the minimum size of the coupler as well as its required operating conditions are ensured. To this end, we employ a surrogate‐assisted technique involving a trust‐region gradient search framework. Computational efficiency of the design process stems from estimating the Jacobian of circuit responses at the level of a low‐fidelity model of the cascade. The latter is composed in a circuit simulator from duplicated EM‐evaluated data blocks of a single cell and is well correlated with the corresponding high‐fidelity model. The key advantage of this work is the utilization of a reconfigurable, cheap, and well‐aligned low‐fidelity model. The proposed approach is demonstrated through design of a minimum‐size two‐section branch‐line coupler with quasi‐periodic dumbbell‐shaped cells and meander lines. Excellent circuit performance as well as its small size showcase the reliability and usefulness of the presented method. Experimental verification is also provided.  相似文献   

7.
    
In this article, a wideband and spurious‐suppressed differential bandpass filter based on strip‐loaded slot‐line structure is presented. By means of the differential microstrip‐slot‐line‐microstrip transition, the proposed filter has a wideband bandpass filtering response. Simultaneously, the utilization of the strip‐loaded slot‐line extends its upper stop‐band. The proposed bandpass filter has wider upper‐stopband, wideband bandpass response, and intrinsic high common‐mode (CM) suppression. To verify the design concept, one filter example has been designed, fabricated, and measured. It has a differential‐mode (DM) 3‐dB fractional bandwidth of 157% with a low 0.82 dB minimum insertion loss. What's more, it shows a very wide 20 dB DM stop‐band bandwidth of 6.5 f0d. The experienced results are in good agreement with the theoretical and simulated results.  相似文献   

8.
    
A wideband circularly polarized printed antenna is proposed and fabricated, which employs monofilar spiral stubs and a slit in the asymmetrical ground plane which is fed by an asymmetrical microstrip feedline using a via. The CP operation is realized by embedding an inverted‐L shaped strip and a modified ground plane and can be markedly improved by loading monofilar spiral stubs connected to the asymmetric feedline by means of a via. A parametric study of the key parameters is made and the mechanism for circular polarization is described. After optimization, the impedance bandwidth is approximately 3.6 GHz (4.4‐8 GHz) and the 3 dB axial ratio bandwidth is approximately 3.3 GHz (4.7‐8 GHz), which represent fractional bandwidths of approximately 58.1% and 52%, respectively. Therefore, the proposed antenna is suitable for circular polarization applications in C (4‐8 GHz) band. Compared with other recent works, the simpler structure, wider axial ratio, impedance bandwidths, and more compact size are the key features of the proposed antenna.  相似文献   

9.
    
This article investigates the characteristics of a single/double‐cell composite right/left‐handed (CRLH) resonator and its application on multiple band‐notched ultra‐wideband (UWB) antennas while suggesting an accurate design procedure. Periodicity assumption and calculating a dispersion diagram allow band‐notched frequencies to adequately predict prior to antenna design. Zeroth‐order resonance (ZOR) frequency due to the CRLH characteristics of a mushroom resonator and higher‐order resonance frequencies are predictable through the hypothetical dispersion diagram. To demonstrate this method, compact, printed, ultra‐wideband circular monopole antennas with four/five‐band notched characteristics using a single/double mushroom resonator are presented. The effects of mushroom cell size on ZOR and the other band notched resonant frequencies are also investigated. The numerical simulations show that the asymmetrical unit cell provides the capability to tune both ZOR and band notched frequencies. Comparison between the simulation and measurement results shows reasonable agreement.  相似文献   

10.
第三代移动通信对天线的小型化和多频带提出了越来越高的要求,提出了一种双U型槽和弧形边联合加载的平面倒L天线,采用微带馈电;从蜂窝移动通信、全球定位系统和蓝牙通讯对天线的要求出发,设计了两个四频天线:一个覆盖GSM/DCS/PCS/ISM频段,另一个覆盖GSM/GPS/PCS/ISM频段;应用ANSOFT公司的HFSS10.0三维仿真软件,对天线进行设计和优化,最终得到了两个基本符合频段带宽及方向图要求的四频天线,这对微带天线的小型化和多频带技术具有一定的指导意义。  相似文献   

11.
    
A compact sequential‐rotation array with serial feed and three probes using multi‐layer substrate is proposed. The most compact shape for the microstrip patches are selected with the optimization for the axial ratio and return loss bandwidth. The gain, return loss, and axial ratio bandwidths of the antenna are improved significantly by converting three patches to one circular. The patch radius and the position of probes are selected to form circular Poynting vectors around it where the maximum power is present at large frequency range. While the two layers of the structure use similar board this structure only uses a substrate and three simple pins. Also the total area of the antenna is limited to the microstrip patch and it has a straightforward fabrication steps. So the wideband antenna is relatively inexpensive and compact. The antenna has 21.4% 3 dB axial ratio bandwidth in simulation and 21.1% in fabrication. Consequently, the serial‐multi‐fed circular patch with unique angular and phase arrangements is suitable for many applications as the antenna arrays. © 2014 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:529–535, 2014.  相似文献   

12.
    
Half‐hexagonal microstrip antenna (H‐HMSA) is a compact version of HMSA, as it resonates at the same fundamental mode frequency. In this article, a compact configuration of a single layer, broadband gap‐coupled H‐HMSA has been proposed. Gap‐coupled H‐HMSA is fed indirectly by a λ/2 microstrip‐line resonator. Broad bandwidth (BW) is achieved with an effective use of resonance introduced by λ/2 resonator and gap‐coupled half‐hexagonal radiating patches. A peak gain of 7.07 dBi and measured BW (S11 ≤ ?10 dB) of 11.5% at the center frequency of 5.2 GHz have been achieved, which occupies a small volume of 0.023 λ03 including the ground plane. The radiation patterns remain in the broadside direction throughout the return loss BW. Simulated results of the proposed antenna configuration are experimentally validated with good agreement.  相似文献   

13.
    
A circularly polarized printed antenna using an asymmetric open‐slot is designed in this paper. The presented antenna consists of conducting ground plane with open wide‐slot, fed electromagnetically by a microstrip feedline. The slot and feedline are positioned at the edge of the ground plane and substrate, hence making the antenna asymmetric. The measured results show that the |S11| < ?10 dB impedance bandwidth is 125% (3.2‐14 GHz) and the broadband axial ratio bandwidth is 61% (3.2‐6 GHz). The antenna is very simple and has a small size of 25 mm × 25 mm, making it attractive for compact wireless WLAN, ISM, WiMAX, and C‐band applications.  相似文献   

14.
    
A novel design of a balanced wideband power divider (PD) with enhanced common‐mode (CM) suppression is proposed. The top and bottom layers of the structure contain tapered microstrip line. Those microstrip lines are coupled via slotline in the ground plane, which is located at the middle layer. With appropriate placement of the slotline, the coupling between the slotline mode and the differential‐mode (DM) signals can be maximized, while that between the slotline mode and the CM signals can be minimized. Simulated and measured results show that the proposed PD has equal power division, low insertion loss, and good return loss. In the measurement, the fractional bandwidth of the measured ?10 dB (DM) return loss is about 101% (1.82–5.35 GHz), the insertion loss for the DM signals is less than 5 dB, the suppression of the CM signals is higher than 45 dB, and the DM isolation is better than 10 dB over the fractional bandwidth. © 2013 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:437–442, 2014.  相似文献   

15.
    
In this article, two novel topologies of compact‐size dual‐band single‐ended‐to‐balanced power dividers that are loaded with open‐ and short‐ended stubs are presented. Quarter‐wavelength open‐ended stubs and half‐wavelength short‐ended stubs are respectively exploited in the proposed dual‐band power‐divider configurations to incorporate the dual‐band functionality into them for flexibly‐adjustable dual‐frequency‐ratio specifications. Each engineered five‐port power‐divider circuit features high in‐band input/output power‐matching levels, high in‐band power‐isolation levels between the two differential‐mode outputs, and high common‐mode‐rejection levels in a broad spectral range. Two microstrip prototypes designed at 0.9/1.8 GHz (GSM bands) and 1.57/2.45 GHz (GPS and WLAN bands) are constructed and characterized for experimental‐demonstration purposes.  相似文献   

16.
    
This article presents a novel methodology for the design of transmission line‐based dual‐band branch‐line hybrid with distinct power division over any two specified frequencies. These distinct power divisions at specified frequencies are achieved while keeping the quadrature relation intact at both the frequencies. To demonstrate the effectiveness of the proposed technique, a prototype of dual‐band uneven branch‐line hybrid operating at 1960 and 3500 MHz has been designed for use in Wideband Code Division Multiple Access (WCDMA) and Worldwide Interoperability for Microwave Access (WiMax) applications. The designed hybrid possesses equal power division in the WCDMA band and 3‐dB unequal power division in the WiMax band. © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2013.  相似文献   

17.
    
This article presents a compact model to reduce the physical size and increase the frequency ratio between the second and first resonance frequencies of a dual‐function stepped‐impedance‐stub (SIS) line, which was subsequently employed in the realization of dual‐band branch‐line couplers. The proposed model comprises of a loaded spiral T‐shaped SIS that reduces the size of a conventional SIS line as well as improving its frequency ratio. The proposed model behaves exactly similar to the recently developed dual‐band resonators with the advantage of size reduction of ～35% as well as having a wide range of realizable frequency ratios between 1.4 and 3.7 compared to 1.7–2.7 and 1.8–2.3 for the conventional SIS and T‐shaped transmission‐lines, respectively. Dual‐narrowband and wideband branch‐line couplers were developed based on the spiral T‐shaped SIS lines. The dual‐wideband device's bandwidth was enhanced by 2.7% accompanied by a size reduction of 58.6% in comparison with the conventional dual‐wideband couplers operating at the same frequencies. The theoretical results were verified by measurement. © 2011 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2011.  相似文献   

18.
    
In this paper, a new design of microstrip power limiter which is based on microstrip technology and zero bias Schottky diode is introduced. In this context, the FR‐4 substrate that was characterized by dielectric permittivity (4.4), dielectric thickness (1.6 mm), and the HSMS 286k Schottky diode is used to design the proposed power limiter. The planar resonators are designed, optimized, and simulated with the shunting of the HSMS 286k diodes by using Schematic solver integrated in ADS from Agilent Technologies. The simulation results are significant in terms of high impedance matching, strong insertion of the low power, and good limitation ratio of the high power. The proposed power limiter is fabricated and tested in the measurement part. It is observed that the results are in agreement with the numerical analysis in terms of matching, isolation, and power limitation. The achieved microwave power limiter offers simple construction, small size (44 × 40 mm2), wide bandwidth, and good limitation ratio less than 10 dBm when the input power reaches 30 dBm.  相似文献   

19.
    
In this article, a modified microstrip Wilkinson power divider with harmonics suppression for GSM communications applications is presented. For low‐pass filter designing, one open stub, one radial resonator, and two rectangular resonators are used. According to results related to insertion losses (|S21| and |S31|), stopband is wide and equal to 7.5 GHz (3.4‐10.9 GHz), under the condition of 20 dB harmonic suppression level. The results show that at the designed frequency of 1.8 GHz, the input return loss (|S11|) and output return losses (|S22| and |S33|) are better than 22 dB, and the isolation between of output ports (|S32|) is better than 30 dB. The size of the proposed power divider is compact and equal to 10.6 × 14.6 mm2. Finally, the proposed power divider was fabricated and the measurement results illustrate a good agreement with simulation results.  相似文献   

20.
    
The purpose of this article is to provide a comprehensive investigation on the resonance phenomenon of microstrip line coupled complementary split‐ring resonator (CSRR) with different orientation and relative size. It is shown that when the relative size of the CSRR is smaller than the host line, the CSRR with its slit oriented orthogonal to the line axis will not excite effectively and show weak resonance behavior. However, when the slit is positioned along the line axis, the cross‐polarization effect comes into play, which excites the CSRR through the mixed coupling. To ensure the correctness, several numerical simulations are carried out for different substrate height and relative permittivity. Finally, a prototype is fabricated and measured for the experimental validation.  相似文献   

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