Broadside Coupling Research Articles

A proposal for design of 2 – 4 GHz wideband bandpass filter using suspended substrate stripline for passive radar systems

This article proposes a solution to design of front-end bandpass filters which finds application in wideband receivers for passive radar systems. The structure employs suspended substrate stripline as base transmission lines, dual-frequency resonators, and broad-side coupling patterns to render a wideband, steep cutoff and low-loss bandpass filter that aims at replacing lossy microstrip-based or bulky waveguide-based filters. The structure is able to scale to different operating frequency ranges in electronic warfare systems.

A novel differential‐fed frequency beam scanning antenna with low sidelobe

AbstractIn this letter, a novel differential‐fed frequency beam‐scanning antenna is introduced. This differential structure is achieved by leveraging quasi‐Yagi radiating elements within a four‐layered geometry. Within this configuration, the element is excited by a pair of out‐of‐phase slow‐wave meander lines, through which differential signals are transmitted. These lines can be seamlessly integrated with other differential circuits. To ensure robust coupling, a broadside coupling structure is incorporated between adjacent layers. To corroborate theoretical insights, a prototype was constructed and tested. Measurements have shown that the primary beam can be scanned from −33.5° to +32.6° on a lateral plane, covering an operational frequency band of 9–11 GHz. Throughout this frequency range, a consistent peak gain of approximately 16.4 dBi is observed for the antenna.

Novel 6‐GHz/80.8% fractional bandwidth filtering power divider with ultra‐large coupling coefficient using air‐dielectric broadside‐coupled lines

AbstractIn the letter, a wideband filtering power divider (FPD) with ultra‐large coupling coefficient using air‐dielectric broadside‐coupled lines is proposed. The broadside‐coupled line and single transmission line are alternately connected to construct three resonators, which can be used for large bandwidth and high selectivity filtering. An improved substrate‐integrated suspended line (SISL) structure with two inner layers is developed. In the structure, the broadside coupling occurs by the air. The overall structure is implemented based on the low‐cost FR4 dielectric material. The designed FPD is simulated and fabricated. The results demonstrate its excellent performance, with center frequency of 6 GHz, a fractional bandwidth (FBW) of 80.8%, a maximum coupling coefficient of 0.84, an insertion loss of less than 0.29 dB, and an out‐of‐band rejection of more than 52 dB.

Reflectionless Ultra-Wideband bandpass filter based on suspended coplanar waveguide-microstrip broadside coupling

In this paper, a reflectionless ultra-wideband (UWB) bandpass filter (BPF) is proposed based on complementary diplexer, which is composed of a BPF and two bandstop filters (BSFs). BSFs are added to the two ports of the BPF as the auxiliary channels. At the same time, resistors are connected to the terminals of the BSFs to absorb stopband signals of the BPF reflected back to the source. Among them, the BPF consists of four broadside coupled lines of suspended coplanar waveguide-microstrip (SCPW-MS), and the BSF consists of a coupled line and an open-circuited stub. The two complement each other to form the reflectionless UWB BPF. As an example, a reflectionless UWB BPF with center frequency of 5.3 GHz, fractional bandwidth (FBW) of 113 %, and minimum insertion loss of 0.5 dB has been successfully developed. The fabricated device has the advantages of low loss, UWB and self-packaging.

Compact Pixelated Microstrip Forward Broadside Coupler Using Binary Particle Swarm Optimization

Compact Pixelated Microstrip Forward Broadside Coupler Using Binary Particle Swarm Optimization

Comparison of a Genetic Algorithm and Evolutionary Strategies in Optimization of Strip-Structure Modal Filters

The features arising from the optimization of strip modal filters (MFs) using a genetic algorithm (GA) and evolutionary strategies (ESs) are considered. Sequential optimization of microstrip MFs and MFs with broad-side coupling was performed according to the criterion of minimizing the maximum amplitude of the output voltage. The results of such optimization with different numbers of calculations are presented, including the values of the optimized parameters, the objective function, the time spent on the calculation, stopping criteria (when optimized by ESs) and the voltage waveforms at the output of the studied MFs. A detailed analysis of the results of the two algorithms is presented. The advantages and disadvantages, as well as differences in the operation of each algorithm, are determined using the example of optimization of two MFs.

Broadside radiation antenna based on tightly coupled spoof surface plasmon polaritons

A spoof surface plasmon polariton (SSPP) is a hybrid mode of a surface wave in the air and electron oscillation within artificial electromagnetic (EM) media, with the dispersion curve lying below the light line, giving rise to many unique EM properties. In this paper, we investigate the EM properties of tightly coupled SSPP (TC-SSPP) modes and propose a slender broadside antenna based on the TC-SSPP. With the comb structure (CS), dispersion properties of different SSPP modes are firstly analyzed under plane wave illumination, and then we introduce a modified SSPP structure, the broadside-coupled (BC)-CS, to excite and guide TC-SSPP modes. Since TC-SSPP modes can be confined tightly around the slender BC-CS, EM waves can be manipulated within a much more compact space, which is favorable for miniaturization, compactness and the light weight of microwave devices. To demonstrate this, we propose a slender broadside radiation antenna based on the TC-SSPP, using a probe as the feed and a finite-length BC-CS as the radiator. Due to near-field magnetic coupling, the SSPP wave can be excited on the BC-CS. By varying the geometric parameters, the antenna can radiate in the broadside direction. A prototype was designed, fabricated and measured. Both the simulated and measured results verify our design.

МАТЕМАТИЧЕСКИЙ АППАРАТ ДЛЯ АНАЛИЗА ПОМЕХОПОДАВЛЯЮЩИХ ПОЛОСКОВЫХ УСТРОЙСТВ С АСИММЕТРИЧНОЙ СТРУКТУРОЙ

A mathematical apparatus that is used to analyze protective devices based on a meander line (ML) turn. The apparatus takes into account the effect of asymmetry of cross-section on the propagation of pulse signal in a turn The developed mathematical apparatus includes: a model for calculating radiated emissions from a turn with an arbitrary cross-section; an analytical model for calculating the time response at the turn output; models for obtaining conditions that ensure the complete ultrashort pulse (USP) decomposition in multistage devices The proposed apparatus was evaluated on the example of structures with broad-side and side coupling (by the comparison with the results of computer simulation). As a result of comparison of frequency dependences of the maximum electric field strengths obtained using the model and numerically were produced ambiguous results. For the ML turn with broad-side coupling, the dependences were found to be in good agreement qualitatively in the frequency range up to 2.5 GHz. However, they can differ significantly in terms of quantity. More specifically, at some frequencies, there are pronounced maxima of the frequency dependences obtained numerically. For the turn with side coupling, the amplitudes of the maximum field strengths calculated by the model were found to be higher in the entire frequency range (with the exception of several maxima) than those calculated numerically. The constructed directional diagrams of the turn confirm the quantitative discrepancies. Meanwhile, the analysis of the obtained results allows us to claim that the real field strengths will be lower than those calculated by the model, so the model is applicable for preliminary estimates. As a result of evaluation of the analytical model for calculating the time response at the turn output revealed a complete coincidence of the time responses obtained on the basis of the model and numerically. Finally, the models to obtain the conditions for the complete pulse decomposition were evaluated on the example of 3-stage devices. The results demonstrated that the developed models were correct. The case was also considered when the conditions obtained using the models are not met, which leads to an increase in the signal amplitudes at the output of the devices. Thus, the entire presented mathematical apparatus can be used to analyze protective devices based on an ML turn with an asymmetric cross-section.

Printed collinear dipole array antenna with a horizontally omnidirectional pattern for dual‐band WLAN

AbstractA dual‐band printed dipole array antenna for a wireless local area network (WLAN) application is presented. A radiation element consists of four pairs of printed dipoles, and two radiation elements are collinearly arrayed. A broadside coupling microstrip line‐based two‐sectional impedance transformer is used to feed the radiation elements in parallel. The proposed dual‐band antenna is designed to cover the dual‐frequency bands (2.4–2.48 and 5.15–5.825 GHz) which are the lower‐ and upper‐frequency bands for WLAN operation. The experimental results support the proposed design theory and also exhibit the gain values of 3.89–4.88 and 5.79–7.18 dBi at the lower‐ and upper‐bands, respectively, maintaining the omnidirectional radiation pattern. The measured radiation efficiencies at each frequency points, 2.4, 5.2, and 5.5 GHz are 87.39%, 75.43%, 69.96%, and 73.07, respectively. In addition, for mass production, the effect from a low‐cost flexible coaxial cable, and polyethylene housing on the antenna performance is also investigated in this letter.

Enhanced spin wave coupling between array of spin torque nano oscillators in magnonic crystal cavities

Spin wave coupling between nano contact spin torque nano oscllators in asymmetric and symmetric array of antidot MC cavities to obtain sustained spin wave oscillations using supercell plane wave method and micromagnetics is discussed. The SWs were excited by injecting a spin-polarized current into a single nano contact in a L3 magnonic crystal cavity(MCC) and radiate like an end-fire antenna. The SW oscillations are then coupled into one of the guided modes of a magnonic crystal waveguide (MCW). The MCC acts as a SW resonator and spin-torque injection as gain. Together they achieve sustainable oscillations in a manner analogous to the behavior of a laser cavity. The phase locking of arrays of cavities arranged symmetrically and asymmetrically on both sides of a MCW is also discussed. Spin waves are radiated like a broadside antenna. The PSD of the broadside case is 28 dB lower than that of the end-fire case. The obtained value from the micromagnetic simulation is used to find the corresponding point in the guided mode of MCW, and this occurs nearer to the edge of the Brillouin zone. We also investigated the point in dispersion where the maximum energy is coupled from MCC to MCW. The spectral characteristics of the broadside coupling were correlated with frequency pulling effects in the laser cavity. Asymmetric spin-torque excitations on either sides of the MCW cause odd frequency peaks in the PSD characteristics. This can be mitigated when we use MC cavities placed symmetrically on both sides of the MCW, and excite spin waves in each cavity. However, spin waves excited in an asymmetric array of cavities add in phase, yielding a power enhancement with an increase in the number of cavities. Spin waves excited in a symmetric array of cavities add out of phase and result in spin-wave decoherence with an increase in the number of cavities.

A tunable reflection‐type filtering phase shifter using SISL technology

This letter proposed a novel tunable reflection-type phase shifter (RTPS) with a filtering function using substrate-integrated suspended line (SISL) technology. First, a novel 3-dB branch-line coupler with a filtering function is designed by using broadside coupling lines. On this basis, the filtering RTPS is realized by combining with a series varactor network. The proposed SISL filtering RTPS can obtain a continuous phase shift range of 104° under 0–30 V DC bias control, which enables multifunctional integration of phase shifters. All circuits are implemented on the SISL platform, which has the advantages of double-sided wiring, self-packaging, and low loss.

Optimization of a broad-side coupling modal filter by evolutionary strategy algorithm with setting the ranges of the optimization parameters

The paper considers the optimization of a modal filter with broad-side coupling by evolutionary strategy algorithm with limitations (i.e., setting the ranges of the optimization parameters). An improved block diagram of the algorithm with limitations is presented. The sequential optimization that uses the original and improved algorithms with different numbers of computations is performed. The performance of the improved algorithm is demonstrated. The main advantages and disadvantages of this algorithm are shown.

Ultrasensitive terahertz sensing with broadside coupled polarization insensitive graphene metamaterial cavities

The ubiquitous property of metamaterials to confine energy at deep-subwavelength scale paves the way to leverage strong light (or terahertz)-matter interactions towards the development of efficient, state-of-the-art sensing technologies at the terahertz (THz) frequencies. In two-dimensional active metamaterials, for instance, graphene metasurfaces; THz-matter interactions are largely governed by the near-field coupling, where strong field confinement is predominantly achieved within very small areas (compared to total device area), viz, in split gaps, narrow apertures etc. Here, we demonstrate a polarization insensitive broadside coupling mechanism in graphene- metamaterials, which is beneficial for realization of miniaturized, compact, ultra-sensitive THz thin film sensors with substantially large effective areas for strong THz-matter interaction. Proposed structure entails ultrathin layer of dielectric spacer (cavity) sandwiched between two “plus” shaped sub-wavelength graphene resonators. In order to investigate the sensing capabilities, obscure materials are placed in ultrathin cavity region to detect its refractive indices. A record high refractive index sensitivity of around 2.8 THz/RIU substantiates the utility of introducing the concept of broadside coupling in graphene metamaterials. Further, we employ the Lorentz oscillator based coupled mode theory in order to elucidate the numerical outcomes.

Broadband Bandpass Filter for UWB Networks with Multiple In-Band Transmission Zeros

Proposed in this manuscript is a broadband bandpass filter (BPF) with dual in-band transmission zeros (TZs) and elongated stopband for application in ultra-wideband (UWB) networks. The basic structure is developed on the principle of broadside coupling of microstrip-to-coplanar waveguide (CPW). Semi-elliptical microstrips on the top are arranged in back-to-back manner and coupled to the open circuited CPW in the ground. The basic BPF is of 3rd order with good insertion/return loss. To this basic BPF structure multiple defected ground structures (DGS) in the shape of complimentary split ring resonator (CSRR) are appended to place dual Tzs within the passband and later dumbbell-shaped DGS are engraved in the CPW to widen the stopband. Also, an approximate equivalent lumped element circuit model is developed and its frequency characteristics matched against full-wave EM simulation. The proposed dual notched BPF is finally fabricated and is found to occupy a compact area of 13.6 × 6.75 mm2.

Widebandlog‐periodicphase shifters

This paper presents concept of wideband log-periodic phase shifter (LPPS) and also three novel microstrip phase shifters using a log-periodic structure for the first time. The process of achieving the goal of wideband releases three main-line models with different characteristics. The design process follows a log-periodic phase shifter theoretical analysis and optimization algorithm of the desired designing platform for circuit tuning. Three proposed main-line log-periodic phase shifters are short-circuited stub LPPS (SS-LPPS), double-sided LPPS (DS-LPPS), and Multilayer coupling LPPS (MC-LPPS). Compact size, planar, ease of fabrication, and wideband are the critical characteristics of the proposed structures. The broadband characteristic of the MC-LPPS is due to top and bottom Log-Periodic microstrip patches broadside coupling of 2 dB through an elliptical slot placed in a ground plane as a middle layer of a structure. Even-odd model analysis of design verification method employed. The optimized overall dimension of the final wideband proposed structure on the low-cost Rogers RO4003C substrate is 35 mm × 20 mm, Fabricated and tested. Experimental and simulation results have good agreement. S11 and S21 are better than −10 and − 1.45 dB in considered 141% fractional bandwidth (1.40-8.11 GHz) for a 130° continuous phase gradient, respectively.

A 10–50-GHz UWB BPF With GSG Probe Transition Using Micromachined Rectangular Microcoaxial Line

This article presents a millimeter-wave (mmW) ultrawideband (UWB) bandpass filter (BPF) using micromachined rectangular microcoaxial line ( \textRμCL). The tightly coupled stepped-impedance stub loaded resonator (TC-SISLR) exhibiting multiple-mode resonator (MMR) property, which has nine controllable transmission poles (TPs) and two controllable transmission zeros (TZs), is proposed to achieve the design goal. Nine controllable TPs of TC-SISLR can support a 10-50-GHz UWB passband, while two controllable TZs of TC-SISLR can provide a sharp rejection passband. Step-to-step design process is given to guide the 10-50-GHz UWB BPF design, and the vertical broadside coupling configuration and the defected ground structure (DGS) are introduced to strengthen the tight coupling. Moreover, the \textRμCL-to-ground-signal-ground (GSG) probe transition is also proposed and designed for on-chip measurement. As examples, the back-to-back GSG probe transition is fabricated, which has a low loss of 0.19 dB within 10-50-GHz passband, and a low loss of 0.6 dB up to 110 GHz. A 10-50-GHz UWB BPF with GSG probe transition is also fabricated, which has a minimum insertion loss of 0.44 dB within 10-50-GHz passband.

Design of a Differential Coupled-Line Directional Coupler Using a Double-Side Coplanar Waveguide Structure With Common-Signal Suppression

In this work, a rigorous approach for the design of a differential coupled-line directional coupler (DCLDC) implemented in double-side coplanar-waveguide (CPW) technology is presented. Due to the double symmetry of the structure, it is possible to obtain the coupling level and port characteristic impedances of the coupler in a simple and efficient way. In addition, due to the broadside coupling of the involved differential CPW lines, a wide range of coupling levels can be covered. Design curves relating the geometrical parameters of the structure to the electrical parameters of the DCLDC are provided, and a 3-dB coupler with an impedance of $50~\Omega $ at the terminal ports has been designed, fabricated, and measured. Common-mode (CM) transmission to both through and coupled output ports has been reduced by adding a simple and compact CM filter at the input port. The good agreement between the results obtained with EM simulation, transmission line models, and measurements confirms the benefits of the proposed structure and the suitability of the design procedure.

Multicriteria optimization of a meander line with broad-side coupling by genetic algorithms

Multicriteria quality functions for the dungerous pulse splitting into a sequence of pulses of smaller amplitude were formulated. The optimization was performed by simple genetic algorithm using these functions. As a result, 3 sets of optimal parameters providing the given criteria were obtained. Comparison of the results of the heuristic search and genetic algorithm showed their similarity. As a result of the genetic algorithm optimization in accordance with the formulated criteria, the attenuation (times) achieved 2.5 for the set of parameters one, 3.3 – for set two, and 3.42 – for set three.

A Dual-Band Coupled Line Power Divider Using SISL Technology

A coupled-line based dual-band power divider using substrate integrated suspended line (SISL) for WLAN application is proposed in this brief. Two-section cascaded coupled line in each output path is used for dual-band response. One coupled line loaded at the input port is to improve the frequency selectivity. Two lumped resistors placed between two pairs of the two-section coupled line are used for isolation enhancement. Multi-layer SISL structure is introduced to realize tight broadside coupling, as well as for low loss, miniaturization and self-packaging. To further reduce the dielectric loss, the suspended substrate is cut out in specific pattern. The proposed dual-band power divider (DBPD) is analyzed using the even- /odd- mode method, the S-parameters are derived, and the design procedure is exhibited. For verification, a DBPD prototype working at 2.45 / 5.13 GHz is implemented. The measured results agree well with the simulated ones. The two passbands are from 1.7 GHz to 3.1 GHz and from 4.6 GHz to 5.5 GHz, with fractional bandwidth (FBW) of 58.3% and 17.8%, respectively. The measured return loss and isolation are both better than 15 dB in both passbands.

86 to 94GHzlow lossCMOSbalanced resistive mixer using an asymmetric broadside coupler and delay lines

AbstractAn 86 to 94 GHz balanced resistive mixer (BRM) is presented using a 65 nm complementary metal‐oxide‐semiconductor (CMOS) process. We minimize parasitic losses which are serious at high frequency by adopting symmetric transistor structures. A low loss 180° hybrid is implemented using an asymmetric broadside coupler and delay lines. This allows low‐loss implementation of 86 to 94 GHz BRMs, which represent a conversion loss of 10.3 to 13.0 dB from 86 to 94 GHz of RF frequencies. The balanced designs produce LO‐to‐RF isolations of 32 to 36 dB from 87 to 93 GHz. The proposed CMOS BRM shows competitive results when compared to GaAs‐ or InP‐based balanced resistive mixers having moderate LO power requirements.