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2013-06-09 PIER Letters Vol. 40, 201-207, 2013. doi:10.2528/PIERL13050402

Design of Compact Wideband Bandpass Filter with Good Performances Based on Novel CRLH Resonator

Guo-Cheng Wu, Guangming Wang, and Ya-Wei Wang

A novel miniaturized composite right/left-handed (CRLH) transmission line based on the structure of spiral inter-digital is proposed and analyzed in this article. Compared with the conventional inter-digital CRLH, the proposed CRLH realizes a 25% resonace frequency shift, and the miniaturization is realized. Then, a compact bandpass filter centered at 1.00 GHz with minimum insertion loss 0.42 dB was designed, fabricated and measured. The measured results show that the band width is 61.6% and that the sharpness at the two edges of passband is 212.5 dB/GHz and 607.1 dB/GHz. This designed filter has very high selectivity. Besides, the whole size of the designed filter is 0.114λ×0.054λ. The filter realizes the miniaturization effectively, and this designed bandpass filter has good performances and smaller size than the same works in references.

2013-05-30 PIER Letters Vol. 40, 191-200, 2013. doi:10.2528/PIERL13032115

Compact Reconfigurable HMSIW Bandpass Filter Loaded by CSRR

Zhudan Wang, Feng Wei, Li Zhang, and Xiao-Wei Shi

A reconfigurable half-mode substrate integrated waveguide (HMSIW) bandpass filter (BPF) loaded by complementary split-ring resonator (CSRR) is investigated. The proposed HMSIW-CSRR structure allows the implementation of a forward-wave passband propagating below the characteristic cutoff frequency of the waveguide. By changing the effective capacitance to ground of the CSRR, frequency tuning of the resonator is observed without other external circuit. The proposed filter exhibits improved selectivity due to the employment of the pseudo-S defected structure to generate transmission zero at the low stopband. To verify the presented design method, the predicted compact reconfigurable filter, tuned between 3.6 GHz and 4.5 GHz with insertion loss less than 3.6 dB and return loss better than 17 dB, is fabricated based on the standard printed circuit board process. The measured results are in good agreement with the simulation.

2013-05-30 PIER Letters Vol. 40, 181-190, 2013. doi:10.2528/PIERL13041705

Tri-Band Slotted F-Shaped Antenna with Dual-Polarization Characteristics for WLAN/WiMAX Applications

Jin Yao, Fu-Shun Zhang, Xue Qiang Jiao, and Hao Bai

A tri-band slotted F-shaped antenna with dual-polarization characteristics for wireless applications is presented. The crooked gap and F-shaped monopole are optimized to achieve tri-band operation of 2.4, 3.5 and 5.8 GHz with -10 dB impedance bandwidths of 20%, 14.1%, and 13.6%, respectively. Furthermore, by properly inserting an F-shaped strip on the wide-slot ground, the circular polarization (CP) with a 19% (3.3-4 GHz) 3dB axial ratio bandwidth is obtained. The proposed antenna has a compact dimension of 42×40×1.6 mm3. A prototype of the antenna is fabricated and tested, and an agreement with simulated results is obtained.

2013-05-29 PIER Letters Vol. 40, 171-179, 2013. doi:10.2528/PIERL13013009

A Compact Stacked Circularly Polarized Annular-Ring Microstrip Antenna for GPS Applications

Kang Ding, Tongbin Yu, and Qiao Zhang

A novel design of circularly polarized (CP) annular-ring microstrip antenna (ARMSA) working in TM11 mode is presented. The CP radiations of the proposed antenna are implemented by a 90° branch-line hybrid coupler placed at the inner part of the ARMSA. Since the ARMSA has narrow bandwidth and high-input impedance, a circular parasitic patch suspended above the ring is employed for not only improving the impedance matching and bandwidth, but enhancing the performances of axial ratio (AR). Due to the utilizing of parasitic patch and circular hybrid, the measured results are shown to attain a 10-dB return loss bandwidth of 31.2% (1300-1780 MHz) and a 3-dB AR bandwidth of 19.2% (1360-1650 MHz) respectively. The CP gain is 8.2 dB at 1.575 GHz. The proposed antenna is low profile and has a simple structure, therefore, it can be a good candidate for GPS portable terminal applications.

2013-05-29 PIER Letters Vol. 40, 163-170, 2013. doi:10.2528/PIERL13040104

A Novel Wideband Bandpass Filter Using Triple-Mode Slotline Ring Resonator

Bo Jiang, Lei Zhu, and Dong Chen

A novel wideband bandpass filter on a triple-mode slotline ring resonator is proposed in this letter. By attaching two stubs with different lengths and/or widths to the symmetric plane of a slotline ring resonator, the frequencies of first three resonant modes can be rearranged towards quasi-equal separation. By feeding this slotline resonator using the microstrip feed lines at positions with an angle of 90° to the symmetrical plane, these three resonant modes can be simultaneously raised up, aiming to form up a wide passband. Meanwhile, a wide upper-stopband can be realized by setting the lengths of two stubs unequally. After the principle of an initial wideband filter is described, a prototype of compact filter with internally-loaded stubs is designed with fractional bandwidth of 66% at center frequency of 3.0 GHz. Measured results well validate the predicted ones.

2013-05-29 PIER Letters Vol. 40, 153-162, 2013. doi:10.2528/PIERL13041109

Miniaturized Hybrid Branch Line Couplers Based on a Square-Split Resonator Loading Technique

Lamia Al-Khateeb

In this paper, new miniaturized hybrid branch line couplers loaded by square-split ring resonators are proposed. This loading technique increases the electrical length of transmission lines by patterning the ground plane under the conductor trace in microstrip lines with the complementary, dual-behavior, configuration of square-split ring resonators. Each branch is loaded by one resonator in the first coupler and by two resonators in the second coupler. Hence, compact sizes of 9.29 mm × 9.57 mm, and 8.88 mm × 9.11 mm, or equivalently 0.2λg × 0.2λg and 0.19λg × 0.19λg, respectively, are obtained at the operation frequency, 2.4 GHz. This corresponds to 66.14% and 60.18% of a conventional structure's area, respectively. Moreover, the new designs can suppress higher harmonic components due to the bandstop response of the square-split resonators at their resonant frequency while maintaining similar measured performance compared to the conventional branch-line hybrid coupler. Measured and simulated responses are in very good agreement which validates the proposed structures and technique. This technique can also be applied to minimize the size of other microwave circuits.

2013-05-26 PIER Letters Vol. 40, 141-151, 2013. doi:10.2528/PIERL13020509

Design of Wireless Power Transfer Systems Using Magnetic Resonance Coupling for Implantable Medical Devices

Farid Jolani, Jeetkumar Mehta, Yiqiang Yu, and Zhizhang (David) Chen

Efficient and compact wireless power transfer (WPT) systems are proposed and designed for recharging small implantable medical devices. They use the magnetic resonance coupling scheme to transfer power over a relatively large distance. The receiver resonator coil and the load loop are designed in correspondence to size restriction of implantable devices. The dimensions of the coils are optimized and effective values of the lumped capacitors are investigated and fine-tuned for efficiency enhancement. Three design configurations of the WPT system, each consisting of two coils at the transmitter and two coils at the receiver, are designed and fabricated. The transfer efficiency is measured over different transmission distances and with different orientation angles of the receiver coils. The measurement results show good agreements with the simulations and illustrate that the proposed WPT systems exhibit nearly omnidirectional radiation performance. Furthermore, the receiver coils are implanted inside of a biological object to show the power can be transferred effectively.

2013-05-26 PIER Letters Vol. 40, 129-139, 2013. doi:10.2528/PIERL13030411

Co-Design of a Compact Dual-Band Filter-Antenna for WLAN Application

Wei-Jun Wu, Qi-Feng Liu, Qi Zhang, and Jing-Ya Deng

A co-designed compact dual-band filter-antenna suitable to be embedded inside a wireless access point (AP) in the 2.45/5.2-GHz wireless local area network (WLAN) bands is presented. The proposed filter-antenna comprises a loop-loaded dual-band monopole radiator and a microstrip dual-band pseudo-interdigital bandpass filter. The monopole consists of a uniform width monopole, two identical capacitively loaded magnetic resonators and a top loaded loop. The two magnetic resonators are loaded at the center of the monopole for dual-band operation and the rectangular loop loaded at the top is involved for miniaturization. Instead of using the traditional 50Ω interfaces, the impedance between the filter and antenna is optimized to improve the performance. The filter-antenna and the system circuit board of an AP share the same substrate and ground plane. In this case the design can fully integrate the circuit board of the AP into an internal filter-antenna solution. The proposed filter-antenna provides good selectivity and rejection in out of band regions and omni-directional radiation patterns within the two desired bands. The measured results show good agreement with the simulated ones.

2013-05-24 PIER Letters Vol. 40, 119-127, 2013. doi:10.2528/PIERL13041102

Design of a Compact Dual Band Antenna for Wireless Communications

Hui Zhao, Xiao-Kuan Zhang, Chun-Yang Wang, and Jian-Gang Liang

A compact and planar dual band antenna for wireless communication is presented. The impedance bandwidth of the proposed antenna can cover Bluetooth (2.4-2.484 GHz) and ultrawideband (UWB: 3.1-10.6 GHz) bands. It is composed of a semi-bevelled-rectangle patch and a bended L-shaped strip and fed by a microstrip line. The antenna is built on a FR4 substrate with only 21×35 mm surface area included the ground plane. Details of the antenna design and the measured results included voltage standing wave ratio, radiation patters, peak gain, etc. are presented and discussed.

2013-05-19 PIER Letters Vol. 40, 107-117, 2013. doi:10.2528/PIERL13031808

Computation of the Resonant Frequency and Quality Factor of Lossy Substrate Integrated Waveguide Resonators by Method of Moments

Giandomenico Amendola, Giovanni Angiulli, Emilio Arnieri, and Luigi Boccia

This paper presents a technique for the efficient and accurate determination of resonant frequencies and quality factors of Substrate Integrated Waveguide (SIW) resonators. To consider resonators of a general shape the SIW structure is modelled as a parallel plate waveguide populated with metalized via holes. The field into the SIW cavity is found solving the scattering problem for the set of vias into the parallel plate. Resonances are determined searching for the complex frequencies for which the determinant of the system of equations pertinent to the scattering is zero. To speed up the search, a first guess for the resonance frequency is found using an estimate of the minimum singular value of the system of equations. A Muller search in the complex plane is later used to accurately determine both frequencies and quality factors. Results relevant to resonators of various shapes are presented and compared with results obtained with a commercial code.

2013-05-19 PIER Letters Vol. 40, 93-105, 2013. doi:10.2528/PIERL13031802

Periodic Transmission of Circular Binary Fresnel Zone Plates with Etching Depth and Substrate

Yaoju Zhang, Shilei Li, Yan Zhu, Youyi Zhuang, Taikei Suyama, Chongwei Zheng, and Yoichi Okuno

Based on the scattering theory and the Green function method, a dynamical theory is given for calculating the diffraction of deeply-etched gratings with a stratified structure substrate. The key of our method is that the patterned grating structure is considered as a perturbation to the unpatterned stratified structure rather than to vacuum. Using the first-order Born approximation and in the Fresnel diffraction region, we obtain a simple analytical expression, which can be used to calculating the scattering intensity of deeply-etched circular binary Fresnel zone plates with a stratified substrate (MDECBFZPs). The numerical results show that the focusing intensity at the foci of the MDCBFZP changes periodically with the etching depth and the thickness of the substrate film. Our results are in good agreement with FDTD simulations.

2013-05-13 PIER Letters Vol. 40, 81-92, 2013. doi:10.2528/PIERL13040205

Novel Tri-Band Bandpass Filter Using Stub-Loaded Short-Ended Resonator

Xiu Zhang, Li Gao, Ze Yu Cai, and Xiao-Lan Zhao

This paper presents a tri-band bandpass filter (BPF) using a novel stub-loaded resonator. Different from other stub-loaded resonator, this resonator utilized a short-ended main transmission line and a centerly-loaded open stub. The resonator is theoretically analyzed. The first three resonant frequencies can be individually adjusted and this enables the convenient designs of tri-band BPFs. For demonstration, a tri-band BPF is implemented. Transmission zeros are created close to each passband edge, resulting in high skirt selectivity. Comparisons of the measured and simulated results are presented to verify the theoretical predications.

2013-05-13 PIER Letters Vol. 40, 71-79, 2013. doi:10.2528/PIERL13022707

Novel Compact UWB Frequency Selective Surface for Angular and Polarization Independent Operation

Sanjay Baisakhiya, Ramprabhu Sivasamy, Malathi Kanagasabai, and Sakthivel Periaswamy

This paper deals with a novel miniaturized FSS with wide stop band characteristics for UWB applications. The proposed FSS consists of garland like design printed on either side of the dielectric substrate. The design provides a bandwidth equal to 3.5 GHz at -20 dB reference level of insertion loss which lies within the UWB range. The design delivers stable response for various angular incidences. In addition to this, the symmetrical nature of the FSS holds identical response for both TE and TM Mode of polarization. The proposed geometry is fabricated and its simulated results are validated with measurements. A comprehensive analysis is made by adjusting various parameters associated with the proposed design.

2013-05-12 PIER Letters Vol. 40, 61-69, 2013. doi:10.2528/PIERL13040210

A Compact Triple-Band Fork-Shaped Antenna for WLAN/WiMAX Applications

Liang Xu, Zhen-Yu Xin, and Jun He

A novel triple-frequency fork-shaped antenna for WLAN/WiMAX applications is proposed and investigated in this paper. The presented antenna is simply composed of three radiating elements viz. Stub1, Stub2, Stub3. By adjusting the lengths of the three stubs, three desired resonant frequencies can be achieved and adjusted independently. Experimental results show that the antenna impedance bandwidths for S11 ≤ -10 dB are 2.4-2.65 GHz, 3. 3.3-4.05 GHz, and 5-5.98 GHz, covering the 2.4/5.2/5.8 GHz WLAN bands and 2.5/3.5/5.5 GHz WiMAX bands. Furthermore, nearly omni-directional radiation patterns over the operating bands have been obtained.

2013-05-11 PIER Letters Vol. 40, 49-60, 2013. doi:10.2528/PIERL12110213

One-Step Leapfrog Adi-FDTD Method for Lossy Media and its Stability Analysis

Jian-Yun Gao and Hong-Xing Zheng

A one-step leapfrog alternating-direction-implicit finite-difference time-domain (ADI-FDTD) method for lossy media is presented. Different from the method provided by others, the proposed method is originated from the conventional ADI-FDTD method instead of considering the leapfrog ADI-FDTD method as a perturbation of the conventional explicit FDTD method. Its unconditional stability is analytically proven through a method that combines the von Neumann method with the Jury criterion. In addition, its unconditional stability and computational efficiency are verified through numerical experiments.

PIER Letters Vol. 40, 39-48, 2013. doi:10.2528/PIERL13031502

A Wideband Differential Bandpass Filter Based on T-Shaped Stubs and Single Ring Resonator

Hui Wang, Wei Kang, Guo Yang, and Wen Wu

A wideband differential bandpass filter (BPF) with differential mode passband and common mode suppression is proposed and implemented on microstrip lines for wideband application in this letter. The initial BPF is similar to a single ring resonator with two unequal feed lines which have 180o separation and T-shaped stubs are loaded on the ring resonator to form an improved one for better performances. The lengths and widths of these stubs can be adjusted to produce a highly selectivity under the differential mode and improved attenuation under the common mode. This simple, compact structure is easy for construct without any coupling structure. Finally, a microstrip differential wideband BPF is designed, simulated, fabricated, and measured. The presented differential BPF has a 3-dB fractional bandwidth (FBW) of 38% for the differential mode and insertion loss greater than 17 dB for common mode. Good agreement between simulated and measured results is obtained.

2013-05-07 PIER Letters Vol. 40, 29-38, 2013. doi:10.2528/PIERL13031915

A Novel Dual-Band Passband Filter with Controllable Center Frequencies and Bandwidths

Zhi-Peng Li, Tao Su, Yong-Liang Zhang, and Chang-Hong Liang

A high-order dual-band bandpass filter using novel combined stub-loaded resonators (CSLRs) is presented in this paper. The key merits of the filter configuration are that the center frequency and also the bandwidth of each passband can be controlled conveniently. Moreover, it can build the high-order dual-band bandpass filters using the proposed resonators because of the sufficient coupling through the four symmetric stubs. A fifth-order dual-band bandpass filter designed at 2.5/3.5 GHz was built and tested. The measurement and simulation results agree very well, demonstrating the validity of the method.

2013-05-05 PIER Letters Vol. 40, 19-28, 2013. doi:10.2528/PIERL13032512

Compact Coplanar Waveguide (CPW)-Fed Tunable Wideband Resonant Antennas Using Metamaterial Transmission Line

Long Zheng, Guangming Wang, and Lin Geng

A wideband resonant antenna loaded with coplanar waveguide (CPW) epsilon negative transmission metamaterial line (ENG MTL) unit cells is proposed. The CPW geometry provides high design freedom, and the metamaterial resonant antenna is designed on a CPW single layer where vias are not required. The novel ENG unit cell on a vialess single layer simplifies the fabrication process. The dispersion analysis of the metamaterial unit cell reveals that increasing right hand capacitance and left hand inductance can decrease the half-wavelength resonance frequency, thus reducing the electrical size of the proposed antenna. Based on the proposed ENG MTL unit cell the wideband antenna is verified by a commercial EM simulator HFSS11 and developed. Comparing the measured performances with those resonant antennas, it is noticed that the proposed antenna achieves high bandwidth and further size reduction, higher efficiency and easier manufacturing. The realized antenna has a compact size of 0.32λ0 × 0.20λ0 × 0.012λ0 (26.6 mm × 16.8 mm × 1 mm) at 3.65 GHz, and operates over the frequency ranges 3.38-4.23 GHz suitable for WiMAX applications. Good agreement between the simulated and measured results is obtained.

2013-05-01 PIER Letters Vol. 40, 9-18, 2013. doi:10.2528/PIERL13022701

Compact Dual-Band Circularly-Polarized Antenna with C-Slots for CNSS Application

Maowen Wang, Baopin Guo, and Zekun Pan

A novel compact single-feed circularly-polarized (CP) microstrip patch antenna is proposed for CNSS dual-band application. The antenna comprises a square patch with embedded four symmetrical C-slots parallel to the edges and a slit in the center. The dual resonance frequencies (1616 MHz and 2492 MHz) can be separately controlled by the square patch and the C-slots. The CP characteristics is mainly achieved by adjusting the slit length. The antenna has a low profile and a small size. Details of design and results for the proposed antenna are presented and discussed.

2013-05-01 PIER Letters Vol. 40, 1-8, 2013. doi:10.2528/PIERL13040305

Symmetric Coupled Composite Right-/Left-Handed Transmission Line in Common-/Differential-Mode Operation

Young Kim and Seokhyun Sim

In this paper, a novel four-port symmetric coupled composite right-/left-handed (CRLH) transmission line in common-/differential-mode operation is introduced. The symmetric metamaterial structure is based on a unit-cell which under a differential-mode excitation behaves like a CRLH metamaterial with bandpass filter characteristics. In contrast, the CRLH metamaterial is below the cut-off frequency under a common-mode excitation. To validate these features, a five-cell four-port symmetric CRLH-TL is simulated, fabricated, and measured, and the obtained results verify the bandpass filter features of the structure under differential-mode excitation.