Modal analysis of the microwave frequency response and composite right‐/left‐handed operation of a rectangular waveguide loaded with double positive and double negative materials

This article presents a theoretical study of the electromagnetic wave propagation in a rectangular waveguide, loaded with double positive (DPS) and double negative (DNG) dielectrics. The frequency response of the waveguide is analyzed using a modal technique. The results show that when at least one of the dielectrics is a DNG material the cutoff frequency of the waveguide is much more lower than the cutoff frequency of the DPS loaded or the empty waveguide. This interesting property means that very low frequency signals could be guided by structures that have very small size. Properties of composite right‐ and left‐handed wave propagation are also observed as well as the characteristic stop‐band between the frequency regions in which RH and LH wave propagation occurs. © 2007 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2007.     

Parameter extraction of interdigital slow‐wave coplanar waveguide circuits using finite difference frequency domain algorithm

The slow wave effect can be obtained by a capacitively loaded structure with a symmetrical interdigital line connected on both sides of the coplanar waveguide (CPW) central line. The ferroelectric thin film with high dielectric constant can reduce the size of circuit and make it possible to realize tunable devices such as filter by applying voltage on it. Actually, this kind of slow wave structure is a periodic guided‐wave structure and can be analyzed by using classic finite difference frequency domain (FDFD) method for periodic guided‐wave structures. However, the very compact slow‐wave structures will usually result in simulation errors when the classic FDFD method is adopted, which will lead to a nonsymmetrical generalized eigenvalue problem. In this article, the shift‐and‐invert (SI) Arnoldi method is used to directly resolve this nonsymmetrical generalized eigenvalue problem. As a result, the accuracy of FDFD algorithm is improved. Especially for the large scale eigenvalue problem, SI method can also have a very fast speed of calculation. By means of its complex propagation constant obtained from simulation, one can extract circuit parameters of the interdigital capacitor. Consequently, one can analyze and design relevant resonators and filters in a quick and accurate manner, which are constructed with such interdigital slow wave structures. © 2008 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2008.     

Design and layout techniques for a mm‐wave body‐biased variable‐gain amplifier

A two‐stage mm‐wave variable‐gain amplifier is designed and implemented in a 65‐nm CMOS technology. A fully symmetric layout has been utilized to suppress the odd‐mode of propagation and increase the quality factor in co‐planar waveguide transmission lines. Moreover, a new design technique is proposed for implementing decoupling capacitors for mm‐wave frequencies. Body‐biasing technique is utilized to change the amplifier gain without significant change in the overall power consumption of the circuit. The measurement results show that the amplifier achieves a peak gain of 10 dB with a gain variation range of 25 dB while consuming 12 mW from a 1.2‐V supply. © 2013 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:470–477, 2014.     

Compact quad‐channel high‐temperature superconducting diplexer based on stub‐loaded square ring resonator

A compact quad‐channel high‐temperature superconducting diplexer based on stub‐loaded square ring resonator (S‐LSRR) is proposed. The proposed resonator consists of a square ring with symmetrically loaded two open‐circuited stubs and provides four resonant modes for quad‐channel applications. Even‐ and odd‐mode methods are applied to analyze the S‐LSRR. Analytical study shows that four resonant modes of one S‐LSRR can be designed in two pairs and applied to construct two of four channels of the designed diplexer. A square patch is added to the resonator for providing an additional parameter to tune the resonant modes. Based on the proposed resonator, a quad‐channel diplexer with center frequencies of 2.4, 3.2, 3.9, and 5.6 GHz is designed. For demonstration, the diplexer is fabricated on 2‐in‐diameter 0.5 mm‐thick MgO wafer with double sided YBa₂Cu₃O_y films and measured at 77 K. Good agreement between the simulation and measurement is obtained. The diplexer has a compact size of 0.25 λ_g × 0.45 λ_g, where λ_g is guided wave length at the center frequency of first channel.     

Dual‐band rotary standing‐wave voltage‐controlled oscillator

In this article, a dual‐band rotary standing‐wave oscillator (RSWO) is introduced that generates sinusoidal signals by the formation of a standing wave on a ring (closed‐loop)‐distributed composite right/left‐handed (CRL) Inductor‐Capacitor (LC) transmission line network. The LC network consists of four unit cells of CRL LC resonator stacked in series, and two pairs of cross‐coupled transistors are used to compensate for the loss of LC resonator. Varactors are used as the control to switch on/off the high‐ or low‐frequency bands. In the fundamental mode, the RSWO operates at the high‐frequency band. In the harmonic mode, the oscillator provides low‐frequency band outputs. The dual‐band function exploits the multiple oscillation modes of the CRL RSWO. The proposed RSWO has been implemented with the Taiwan Semiconductor Manufacturing Company, Limited (TSMC) 0.18‐μm SiGe BiCMOS technology. It can generate differential signals in the high‐band frequency range of 6.73–8.60 GHz and in the low‐band frequency range of 3.68–3.73 GHz. The die area of the RSWO is 1.123 × 1.123 mm². © 2014 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:536–543, 2014.     

Ultracompact two‐way and four‐way SIW/HMSIW power dividers loaded by complementary split‐ring resonators

In this paper, two ultracompact power dividers based on the substrate integrated waveguide (SIW) and half‐mode SIW (HMSIW) technologies loaded by complementary split‐ring resonators (CSRRs) are presented. The presented structures are designed based on the theory of evanescent mode propagation. To obtain a size reduction, the CSRR unit cells are etched on the metallic surface of the SIW and HMSIW structures. First, a two‐way HMSIW power divider is reported. In this circuit, the concept of HMSIW is utilized aiming at a further size reduction in addition to the size reduction by the CSRR unit cells. Then, a four‐way SIW power divider is designed so that the direct coaxial feed is used for the input port and microstrip transmission lines are used for the output ports. Both two‐way and four‐way SIW/HMSIW power dividers at 5.8 GHz covering WLAN are designed, fabricated, and measured. They respectively have 0.18 × 0.21 λg² and 0.38 × 0.21 λg² total size. A fair agreement between simulated and measured results is achieved. The measured insertion losses are 0.5 ± 0.5 and 0.6 ± 0.5 dB for the two‐way and four‐way SIW/HMSIW power dividers, respectively, in the operating band of interest.     

Design and analysis of wideband eight‐way SIW power splitter for mm‐wave applications

High‐performance, wideband three‐stage power splitters based on substrate integrated waveguide (SIW) are presented. Broadband‐tapered microstrip transitions are used for feeding the SIW structures, which provide 7.5 GHz bandwidth from 21.5 to 29 GHz with return loss below ?20 dB. In addition, various T junctions are tuned, not only to provide broadband performance up to mm‐wave frequencies but also offer low‐phase and amplitude imbalance when cascaded in multistage 1 × 8 splitters. 1 × 4 and 1 × 2‐T junctions are adjusted through parametric analysis to provide wide bandwidth of 3.5 GHz at 24.5 GHz and ?15 dB reflection coefficient. The optimal microstrip transitions and T junctions are used to design a broadband, eight‐way power splitter with 15 dB return loss from 23.0 to 26.4 GHz and phase and amplitude imbalance of ±2.5° and ±0.8° dB, respectively. Furthermore, optimum positions of all inductive posts in terms of guided wavelength are also provided for assisting the direct design of mm‐wave, high‐performance power splitters.     

A 1‐to‐n way single‐ended‐to‐balanced substrate integrated waveguide filtering power splitter

An approach to 1‐to‐n (n = 3, 4…) way single‐ended‐to‐balanced filtering power splitter (SETBFPS) is proposed. The properly placed balanced ports with 0.5λ_g (λ_g is the substrate integrated waveguide [SIW] guided wavelength at f₀) space make the TE32nd 103 and TE32nd 105 modes of n 32nd‐mode SIW multimode resonators form differential‐mode (DM) passband of the SETBFPS. Compared with the state‐of‐art single‐ended‐to‐balanced power splitters, the proposed approach has all the functions of 1‐to‐n way, filtering, and common‐mode (CM) suppression. A 1‐to‐3 way prototype is exemplified at 3.5 GHz with the minimum insertion loss (IL) of 0.09 dB, a fractional bandwidth (FBW) for a 15‐dB return loss of 35%, and a FBW for 15‐dB CM suppression of 52%. Low IL and wide bandwidth can be observed.     

Eighth‐mode SIW based compact high gain leaky‐wave antenna

In this article, a novel electrically small eighth‐mode substrate integrated waveguide (EMSIW) based leaky‐wave antenna (LWA) in planar environment is presented. The proposed antenna uses 1/8th mode SIW resonator which helps to improve compactness of the design while maintaining high gain and increased scanning angle. The proposed SIW cavity is excited by a 50 Ω microstrip line feeding to resonate at dominant TE₁₁₀ mode in X‐band. The dimensions of the resonators are adjusted to keep resonant mode at same frequency. The fabricated prototype is approximately 5λ₀ long. Measured results show that the proposed leaky‐wave antenna is able to operate within frequency range of 8‐10 GHz with beam scanning range of 51° and maximum gain of 13.31 dBi.     

The B‐spline finite element based parabolic wave propagation inside a parallel plate waveguide

A b‐spline based finite element method parabolic wave propagation model is developed and tested against mode summation inside a parallel plate waveguide. The comprehensive numerical analysis of the solution of parabolic wave equation has been done. The algorithm is compared with mode summation in two dimensions. Excellent agreement is observed among the results. © 2013 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2013.     

Analysis on the effect of metal penetrating depth into the anisotropic substrate in a shielded microstripline

This article describes the quasistatic analysis of a shielded microstripline with finite metallization thickness penetrating into the anisotropic substrate. A vertical directional mode‐matching method, which includes eigenfunctions with inhomogeneous properties for analyzing this structure, has been used. This method not only provides a simple and fast approach to the quasistatic analysis of inhomogeneous structures, but also can be applied to analyze the effect of metal penetration into the anisotropic substrate. The results show that the characteristic impedances of a shielded microstripline can be represented as a function of the strip width, the metal thickness, and the metal penetrating depth into the substrate. ©1999 John Wiley & Sons, Inc. Int J RF and Microwave CAE 9: 49–53, 1999.     

Self‐calibration three‐dimensional light field display based on scalable multi‐LCDs

Approach to achieve self‐calibration three‐dimensional (3D) light field display is investigated in this paper. The proposed 3D light field display is constructed up on spliced multi‐LCDs, lens and diaphragm arrays, and directional diffuser. The light field imaging principle, hardware configuration, diffuser characteristic, and image reconstruction simulation are described and analyzed, respectively. Besides the light field imaging, a self‐calibration method is proposed to improve the imaging performance. An image sensor is deployed to capture calibration patterns projected onto and then reflected by the polymer dispersed liquid crystal film, which is attached to and shaped the diffuser. These calibration components are assembled with the display unit and can be switched between display mode and calibration mode. In the calibration mode, the imperfect imaging relations of optical components are captured and calibrated automatically. We demonstrate our design by implementing the prototype of proposed 3D light field display by using modified off‐the‐shelf products. The proposed approach successfully meets the requirement of real application on scalable configuration, fast calibration, large viewing angular range, and smooth motion parallax.     

Both transversal negative permeability and backward‐wave propagation in X‐Band waveguide with double‐side SRR metamaterials

In this article X‐band rectangular waveguides partially filled with the double‐side single ring resonator (DSRR) array are investigated for miniaturization, stop‐band, and multi‐band filters applications. Several rectangular waveguides loaded with the DSRR array in 2–10 GHz frequency band have been studied and optimized. We observe both the transversal negative permeability presented above the cutoff frequency and the backward‐wave located below the cutoff frequency with the DSRR array in X‐band waveguide. Both simulation and measurement results of DSRR array are with good agreement. The DSRR array provides better performance of the transversal negative permeability and the backward‐wave than the split‐ring resonator array. The physical explanation of backward‐wave is presented. The power loss distributions are clearly presented for the negative permeability attenuation and the backward‐wave propagation. © 2016 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:240–246, 2016.     

Miniaturized low‐profile antenna based on uniplanar quasi‐composite right/left‐handed metamaterial

In this article, a metamaterial‐based broadband low‐profile antenna is presented. The proposed antenna employed an array of uniplanar quasi‐composite right/left‐hand (CRLH) metamaterial cells. This structure contributes to exciting the operating modes in lower frequencies. The antenna has an overall electrical size of 0.75 × 0.60 × 0.07 λ₀³ (λ₀ is the center operating wavelength in free space) and provides a 25% measured bandwidth with the center frequency of 5.1 GHz and maximum gain of 6.6 dB. The proposed antenna is an appropriate candidate for WLAN, WiMAX, and other wireless communication applications.     

A self‐packaged wideband filtering power divider based on substrate‐integrated suspended line

In this study, a filtering power divider (FPD) is proposed by utilizing one T‐shaped tri‐mode stepped‐impedance resonator with input/output coupling structures based on substrate‐integrated suspended line (SISL). The circuit topology and SISL technology are combined together to reach balance in performances such as compact size, wideband, high frequency selectivity, low loss, good in‐band isolation, wide stopband, and self‐packaging so that there are no obvious flaws. Wide bandwidth and two near‐band transmission zeros are contributed by the proposed circuit topology. Good isolation can be obtained by comparing different coupling schemes with one resistor. An additional transmission zero for extending the upper stopband can be achieved by the two closely placed stubs without increasing the size of the design. Low loss and self‐packaging can be realized by SISL technology. For demonstration, a prototype is implemented with the size of 0.5λ_g × 0.28λ_g, which exhibits the 1‐dB fractional bandwidth of 26.3%, the frequency selectivity of 0.25/0.37 at the lower/upper edges of the passband, and the insertion loss of 1.1 dB (including transition) at the center frequency (f₀) of 3.34 GHz, while the in‐band isolation is higher than 20 dB and the 15‐dB stopband is achieved up to 3.74 f₀.     

Continuous scanning leaky‐wave antenna utilizing second‐mode spoof surface plasmon polaritons excitation

Continuous scanning leaky‐wave antenna (LWA) based on second‐mode spoof surface plasmon polaritons (SSPPs) excitation has been proposed and validated in this article. Different from the existing modulation methods, connecting axisymmetric rectangular modulation is adopted to excite the ?first harmonic. In this way, the slow‐wave bound on the surface of the transmission line is converted into a radiation wave in space. To the authors' knowledge, this is the first presentation of LWA design utilizing second‐mode SSPPs excitation. In the range from 5.0 to 9.0 GHz, the proposed LWA realizes continuous scanning from ?54° ~ 11° with a quasi‐omnidirectional beam in the vertical plane. A prototype of the proposed antenna is fabricated and measured, and the measured results show good agreement with the simulated. The proposed LWA has potential applications in communication systems and radars.     

Millimeter‐wave antenna with wide‐scan angle radiation characteristics for MIMO applications

A three‐element quasi Yagi‐Uda antenna array with printed metamaterial surface generated from the array of uniplanar capacitively loaded loop (CLL) unit‐cells printed on the substrate operating in the band 25‐30 GHz is proposed. The metamaterial surface is configured to provide a high‐refractive index to tilt the electromagnetic (EM) beam from the two dipole antennas placed opposite to each other. The metamaterial region focuses the rays from the dipole antenna and hence increases the gain of the individual antennas by about 5 dBi. The antenna elements are printed on a 10 mil substrate with a center to center separation of about 0.5 λ ₀ at 28 GHz. The three‐element antenna covers 25‐30 GHz band with measured return loss of 10 dB and isolation greater than 15 dB between all the three ports. The measured gain of about 11 dBi is achieved for all the antenna elements. The three antenna elements radiate in three different directions and cover a radiation scan angle of 64°.     

Full‐wave modeling and optimization of Bøifot junction ortho‐mode transducers

The full‐wave design of broadband ortho‐mode transducers based on the Bøifot junction has two main aspects: an efficient analysis method and a design process divided into tasks with relatively low computational effort. In the analysis part, a rigorous mode‐matching technique has been developed to obtain the generalized admittance matrix of the Bøifot junction. The other elements of the device are also analyzed by mode‐matching. With respect to the design, the proposed procedure starts with the optimization of the individual building blocks of the device. Their interaction is also taken into account in a systematic process. The analysis and design methods have been validated with other numerical methods and an experimental prototype. © 2008 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2008.     

Low‐profile substrate integrated waveguide (SIW) cavity‐backed self‐triplexed slot antenna

A low‐profile self‐triplexed slot antenna is proposed for multiple system integrations. The antenna comprises of hybrid substrate integrated waveguide (SIW) cavity (a combination of a half‐mode circular and half‐mode rectangular SIW), radiating slot, and feeding network. A slot is imprinted on the upper metal‐layer of the SIW which splits the cavity into three radiating sections. It offers tri‐frequency bands when each section is excited separately. By finely tuning the antenna dimensions, it produces three frequency‐bands around 5.57, 7.17, and 7.65 GHz simultaneously utilizes a single slot with maintaining the intrinsic input‐port isolation better than 20 dB. This property helps to introduce the self‐triplexing phenomenon. Compared with the conventional multiband antennas that use an extra circuitry to ensure the port isolations, this design preserves compactness and easy to integrate with planar circuits Moreover, the proposed antenna is fabricated and the measured results mutually agreed with the simulated counterparts. The proposed design can be a feasible option for mobile transceiver applications.     

Ultra‐wideband bandpass filter on coplanar waveguide: Proposal and implementation

In this paper, a novel ultra‐wideband (UWB: 3.1 ～ 10.6 GHz) bandpass filter on coplanar waveguide (CPW) is presented, designed and implemented. At first, an open‐ended nonuniform or multiple‐mode resonator with three distinctive sections is constructed and investigated toward generating the first three resonant modes occurring around the lower‐end, center, and higher‐end of the UWB band. Then, a CPW interdigital capacitor element with enlarged ground‐to‐ground distance is characterized to excite two additional resonant poles below and above the UWB's center. As a result, a five‐pole UWB bandpass filter with only one full‐wavelength is constituted. Its performance is studied on the basis of a simple cascaded transmission‐line network, whose parameters are extracted from our self‐calibrated method of moments. After the optimized results are confirmed by full‐wave simulation over the filter layout, a UWB filter sample is fabricated to demonstrate the actual UWB passband behavior with the 2.8–10.2 GHz bandwidth, where the insertion loss is less than 1.5 dB and variation in group delay is less than 0.33 ns. © 2007 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2007.