A compact substrate integrated waveguide (SIW) filter based on composite right/left-handed (CRLH) resonator units is implemented in this paper. The filter is composed of two CRLH resonator units serially connected by a SIW transmission line unit. The structure of the filter and equivalent circuit transmission behavior are analyzed, and a novel design method by optimizing the length and width of the interdigital metal slots to decrease the filter operation frequency is proposed. To further demonstrate the design theory and performance of the proposed filter, the filter was designed and fabricated on an RT6010 dielectric material. The measurement results show that the proposed filter works at a center frequency of 5.8 GHz with 200 MHz bandwidth. The insertion loss is 2.3 dB, and the filter size is only 10 mm × 7.4 mm.
Complex interconnection structure is a common structure on printed circuit board (PCB). Herein, the paper proposes a method of crosstalk cancellation point at the crosstalk problem between microstrip lines in a complex interconnection structure. First, a model of the coupled transmission lines-channel transmission matrix (CTL-CTM) of the complex interconnection structure is established. Second, the CTL-CTM is simplified through the equivalence of crosstalk-coupling coefficient of parallel coupling microstrip lines to that of the complex interconnection structure. The eigenvalue of the simplified CTL-CTM is then decomposed, based on which the construction of crosstalk cancellation circuit is performed. Simulation results show that the proposed method can effectively improve the quality of eye patterns on complex interconnection structures.
This paper presents an efficient method for evaluating the flux linkage between two circular loops located on the top surface of a plane multilayer soil. The method consists of a rigorous procedure, which leads to expressing the flux as a sum of products of Bessel functions. First, the integral representation for the mutual inductance is cast into a form where the integration range is continued to the negative real axis. Subsequently, the non-oscillating part of the integrand is replaced with a rational approximation, arising from using a well-known least squares-based fitting algorithm. Finally, analytical integration is performed by applying the theorem of residues. As a result of the proposed method, the flux linkage between the loops is expressed as a finite sum of products of Bessel functions. Since no assumptions are made in the mathematical derivation, the obtained explicit expression is valid regardless of the operating frequency. Numerical tests are performed to show the advantages of the proposed method with respect to standard numerical integration techniques. In particular, it is seen how the use of the derived series representation for the inductance with 50 terms permits to achieve the same accuracy as conventional Gauss-Kronrod numerical integration technique, with the advantage of reducing the computation time by at least 8 times.
A wideband end fire antenna architecture in planar technology with fewer turns: helix antenna in planar technology adopting thickness of quarter wavelength is suggested. A wideband 24 GHz helix antenna with 2.25 turns in Rogers compressed RT 4350 technology is presented. The antenna has a bandwidth of 6.2 GHz for S11, gain of 9.3 dBi, half power width of 39.5° and 39° respectively in X-Z and X-Y planes. This helix antenna is characterized by wide bandwidth, high gain, high half power width, compactness and high gain turn ratio. It could also be utilized in antenna design for other frequency bands with compressed PCB technology, as well for on-chip THz antenna design.
In this paper, a graphene-based reflectarray antenna using ENZ (Epsilon-Near-Zero) metamaterial at terahertz (THz) band is proposed, and the performance of its unitcell is investigated. Then, the phase distribution and radiation pattern of the antenna are examined. Benefiting from exceptional complex surface conductivity of graphene which is a novel 2-d material, the size reduction of reflectarray has been facilitated as a result of plasmonic mode propagation within the structure which in turn leads to an increase in propagation constant. Moreover, tunneling phenomenon in ENZ material, a kind of metamaterial which has a relative permittivity under 1, helps reduce the loss. Taking advantage of these outstanding features of both materials, the proposed reflectarray is designed to function at 2.5 THz and is composed of 150×150 elements with square-shape configuration. We have achieved 40 dB of gain using the combination of graphene and ENZ material in reflectarrays, and also it is the first that time they are used together in the reflectarray. This work mainly focuses on the impact of using ENZ material and graphene simultaneously which is not done before, then the results demonstrate that it has a considerable effect on increasing the reflectarray gain.
This letter presents an approach to design a linear phase substrate integrated waveguide (SIW) bandpass filter with good selectivity. The topology of the proposed filter is implemented based on cross and bypass coupling schemes, which simultaneously introduce a linear phase response and good selectivity, respectively. According to the proposed topology, a multilayer SIW filter is presented to realize the two kinds of couplings and preserve a compact size. Then, the defected ground structure is adopted to further improve the out-of-band rejection. To demonstrate the proposed design method, one double-layered SIW bandpass filter is fabricated and measured. Measured results show that the proposed filter has a linear phase response and good out-of-band rejection, as well as a good agreement between simulated and measured results.
A broadband microstrip-to-waveguide end-wall probe transition using a semicircular loop is proposed in this letter. The simulated 20-dB fractional bandwidth for this transition is 48.3% which could cover the whole Ka-band. Then, a compact broadband waveguide termination is developed by combination of this microstrip-to-waveguide transition and a 50 Ω microstrip termination. To reduce parasitic effects, the microstrip termination is grounded by a microstrip radial stub. The fabricated waveguide termination shows a compact size and has a return loss better than 16.6 dB from 26 to 40.8 GHz.
Recently, modern wireless communication applications are extended to call high frequency bands including millimeter waves for 5G systems. Therefore, the propagation properties of such waves in different media have attracted many researchers. In this work, the results of the S-parameters measurements of mortar with four thicknesses are obtained using a nondestructive free space measurement technique for the frequency bands from 8 GHz up to 32 GHz. The obtained results of the dielectric properties and loss factors for the prepared mortar samples are realized. The variation in both the reflection and transmission coefficients and the dielectric properties with curing time conditions of mortar structure is examined. The dielectric properties of water are realized using the proposed method to subtract the effects of water contents from the prepared mortar samples. The effects of the sample thickness and relaxation frequency are considered. The obtained measurements are compared to the simulated results based on a full wave simulation software package of CSTMWS algorithms. Finally, excellent agreements are achieved between the simulated and measured results.
In order to accelerate the speed of matrix-vector product (MVP) in iteration process for adaptive integral method (AIM), a virtual grids technique (VGT) with the multi-dimensional fast Fourier transform (FFT) is proposed. By adding some uniform virtual grids outside the original region, the indexes of nonzeros in the projection matrix are modified so as to eliminate the padding and unpadding procedures in MVP. The advantages of this method are that first it will not occupy any extra memory, and second it makes the Green's function vector compressed from (2Nx - 1)(2Ny - 1)(2Nz - 1) to 8(Nx - 1)(Ny - 1)(Nz - 1) because of its symmetrical block-Toeplitz property. Numerical results show that per iteration time could be reduced more than 30% by applying this method in comparison with the conventional AIM, without losing accuracy. In addition, the peak memory consumption could also be reduced because the intermediate vectors are eliminated.
In this paper, a novel high-order triple-mode half-mode bandpass filter using a single perturbed substrate integrated waveguide (SIW) cavity and a dual-band diplexer are presented. Circular shape metal via-holes are added in the middle of a square SIW cavity as perturbation. The perturbed TE101, TE102 and TE201 resonant modes of the SIW cubic cavity are used to design the proposed filters, which can be shifted to the desired frequency by adjusting the position and size of via-holes. The proposed method reduces the size of the filter, and the measured results indicate that the bandwidth is higher than previous literatures. The dual-band diplexer with a half-mode SIW (HMSIW) structure can be easily implemented based on the proposed BPF through a T-junction, which decreases the number of resonating elements. A triple-mode half-mode filter using a single perturbed SIW cavity with center frequency of 7.43 GHz is obtained. The designed filter and dual-band diplexer are fabricated and measured to validate the present approach.
In this work, computer-aided impedance analysis and genetic-based synthesis of a multiwall carbon nanotube impedance matching section (MWCNTIMS) are proposed. Transmission line model (TLM) of a multiwall carbon nanotube is used for the computer-aided impedance analysis. Continuous parameter genetic algorithm (CPGA) is used for the genetic-based synthesis. A simple, fast and effective impedance analysis and synthesis approach for an MWCNTIMS is presented. The results of the analysis and synthesis for different examples of MWCNTIMS are given and discussed in detail. The results show that the effect of variation of the distance from the ground plane of the outer shell is very small on the values of input resistance and input reactance. The values of input resistance and input reactance decrease while the value of inner radius or the total number of shells increases. Since the diameter increases with the increasing value of inner radius and the total number of shells, the values of input resistance and input reactance decrease with increasing diameter. While the value of nanotube length increases the values of input resistance and input reactance increase.
In this paper, a compact printed monopole antenna with periodic H-shaped slots for WLAN application is proposed, designed and fabricated with standard flexible printed circuit board process. By cutting four H-shaped slots in the radiation patch of the printed monopole antenna, the resonant frequency of the monopole antenna can be reduced; therefore, a compact antenna is realized. The radiator size of the antenna is 0.07λg×0.19λg, which is much smaller than that of a traditional printed monopole antenna. By utilizing electromagnetic simulation software CST, the antenna is simulated and optimized. Moreover, the performance of the proposed antenna is discussed taking into consideration the possible effects of deformations due to the flexibility of the substrate. A sample antenna is manufactured and measured to prove the predicted performance of our proposed antenna. The measured results agree well with the simulations. Hence, the proposed method in this paper is a promising candidate for the design of compact antennas.
A single-layer substrate integrated waveguide (SIW) is developed to design a dual-band band-pass filter (BPF) operating below the cut-off frequency of the SIW, known as evanescent-mode excitation. Gap-coupled excitation is used to demonstrate multiple transmission poles (TPs) and transmission zeros (TZs) below the cut-off frequency of the SIW. The structure is reported to realize two independent evanescent-mode poles on a single-layer SIW which reduces the size and complexity of the structure compared to those of the recent multi-layer evanescent-mode structures. Lumped-element equivalent circuit is employed to describe the EM behavior of the structure for TZs and TPs realization. A compact single-layer dual-band SIW filter is fabricated based on the proposed structure. A good agreement is reported between the measured and simulated performances.
Partitioning large arrays into subarrays can reduce system cost. In this paper, we use identical subarrays to partition a large rectangular aperture. The periodical structure in a large array is broken down by changing the orientations of the subarrays. In each subarray, the element positions are optimized by particle swarm optimization (PSO) to obtain low sidelobe levels. In order to reduce the coupling among the elements, the minimum element distance measured in Euclidean space is restricted in the procedure of optimization. And a modified PSO is proposed to solve the optimization problem with this constraint. Better results can be obtained than the element distance constraint measured in Chebyshev space. This simple but efficient subarray design method is demonstrated through several numerical simulations.
An eccentric harmonic magnetic gear (EHMG) with Halbach array is proposed in this paper. According to the theory of magnetic field modulation and one-side effect, the permanent magnets (PMs) on the inner rotor and outer stator are arranged in a Halbach array. The PMs of inner rotor are divided into three segments per pole, and the PMs on the outer stator are divided into two segments per pole. The proposed EHMG with 15 pole pairs on inner rotor PMs and 16 pole pairs on outer stator PMs is established. The finite element analysis (FEA) is used for simulating the proposed model. The corresponding magnetic field and static torque of the EHMG are calculated. Compared with the conventional EHMG, the results show that the torque density of the proposed EHMG is substantially improved.
In this paper, a novel meta-surface with polarization conversion characteristic in an ultra-wide band is proposed. Based on the principle of the reflected wave cancelation, the proposed meta-surface is distributed as a checkerboard to obtain an ultra-wideband radar cross section (RCS) reduction, resulting from the out-of-phase difference in normal incidence. The relationship between the polarization conversion ratio (PCR) and RCS reduction is investigated and verified by the simulation. Finally, a sample is fabricated and measured in an anechoic chamber. Compared to the metal board with same size, a 5 dB RCS reduction is achieved ranging from 3.7 GHz to 15.9 GHz, which indicates a fractional bandwidth of 124.5%. Moreover, the size of the unit cell is only 0.125λ0×0.125λ0×0.059λ0, where λ0 is corresponding to the lowest frequency, namely 3.7 GHz, indicating the merits of miniaturization and low profile. Experiment results are in good agreement with the simulated ones, which demonstrates the validity of the proposed strategy.
A novel compact 4-way power divider is presented here, which consists of 1/64th mode elliptically curved substrate integrated waveguide (SIW) resonators and radial transmission lines. A direct coaxial fed circular patch acting as the radial transmission line is connected with four elliptically curved 1/64th mode SIW resonators, and these resonators are then connected to output terminals. An equivalent circuit model is developed to understand its behavior. It is designed to operate at 3.6 GHz covering the frequencies assigned for 5G in sub-6 GHz band. Conventional PCB techniques are used to fabricate the prototype. The measured bandwidth is 2.2 GHz, ranging from 2.5 GHz to 4.7 GHz, for which the return loss is less than -10 dB. Also, the transmission coefficient between input and each output for the above-mentioned frequency band is -6.4±0.5 dB. It has a very compact footprint of 0.32λg2, which is at least 40% smaller than various SIW based state of the art power dividers.
In this communication, a new planar monopole ultra-wideband (UWB) antenna with quad notched band characteristics using quad-mode stepped impedance resonator (QMSIR) is investigated. The proposed antenna is composed of a circular-shaped radiating element, a 50 Ω microstrip feed line, a QMSIR, and a partially truncated ground plane. By coupling a QMSIR with an additional outer line beside the microstrip feedline, band-rejected filtering properties around the (5.2/5.8 GHz) WLAN bands and the (7.4/8.2 GHz) satellite communication bands are generated. The measurement of voltage standing wave ratio (VSWR) is in agreement with simulation. The results show that proposed antenna not only retains an ultra-wide bandwidth but also owns quad band-rejections capability. The UWB antenna demonstrates omnidirectional radiation patterns across nearly whole operating bandwidth that is suitable for UWB applications.
In this paper, a periodic interdigital structure for wideband mitigation of differential-to-common mode conversion at the bend discontinuity of differential lines is proposed. A hybrid inductance and capacitance compensation property is exhibited to suppress the common-mode noise of asymmetric transmission lines. An equivalent circuit model is given to explain the working principle of the presented periodic interdigital structure for differential pairs. In comparison with the traditional methods, steep and wideband suppression performances are both observed with the proposed design. Moreover, no additional area is required at the bend discontinuity for compensation. From the measured result, the differential-to-common mode conversion of the differential signals can be mitigated from DC to 10 GHz with a rejection level of -20 dB. The measurements agree well with the simulation predictions.
The reaction concept, introduced by Rumsey in 1954, describes interaction between time-harmonic electromagnetic sources through the fields radiated by the sources. In the original form the concept was a scalar quantity defined by three-dimensional field and source vectors. In the present paper, the representation is extended to four dimensions applying differential-form formalism. It turns out that, in a coordinate-free form, the reaction concept must actually be a one-form, whose temporal component yields Rumsey's scalar reaction. The spatial one-form component corresponds to a three-dimensional Gibbsian-vector reaction which consists of electromagnetic force terms. The medium is assumed homogeneous and isotropic in this paper.