Improved fully-connected neural network approach for decoupling microstrip antenna array design

To suppress the mutual coupling between closely-spaced patches, we propose a two-step decoupling design approach for a microstrip antenna array with the dimensions of 44.9 × 30.495 mm2. The first step is designing a decoupling unit on the basis of waveguided complementary split-ring resonators (WCSRRs) to improve isolation. The second step is presenting an optimization method by using a fully connected neural network (FCNN) to enhance design efficiency. By inserting WCSRRs structure between two patches with the edge-to-edge distance of 0.24λ0 (port-to-port distance with 0.66λ0), where λ0 is the wavelength of free space at a resonant frequency of 9 GHz, the mutual coupling can be reduced to −29.38 dB, which is confirmed by the EM simulation. We use the simulation results of the array geometries and EM performances to train FCNN at first and then use the trained FCNN to predict the array geometric parameters for the optimal EM response when the edge-to-edge distance between patches is further reduced to 0.21λ0 and 0.18λ0 (port-to-port distance reduced to 0.60λ0 and 0.56λ0). The measured isolation of the predicted microstrip antenna array is increased to 41.05 dB and 52.33 dB, respectively. Compared to the EM simulation, our FCNN approach has a higher accuracy and lower computational complexity. Therefore, the proposed array predicted by FCNN has a better decoupling performance. All the simulated and predicted results are validated via the measurement to demonstrate the effectiveness of our design scheme. The advantages of our work include the good decoupling performance of the proposed WCSRRs and the convenient optimization of the FCNN from physical response to optimal antenna array geometry design.

Frequency selection in objective domain plays a vital role in Band-pass filtering. Certain signals are only allowed in the ambit of Band-pass filter and attenuating frequencies outside the range. Complications arise while providing a wider pass-band spread in the domain. This paper proposes a coupling based approach for obtaining a broad spectrum. The methodology involves use of dual parallel coupled micro-strip lines along with double square complementary split ring resonator. The proposed coupling method is found to produce better results in terms of frequency selectivity, rejection rates, fraction band-width, Q-factor along with low average insertion losses in comparison to other filtering techniques.

A microwave filter composed of a microstrip waveguide and a complementary split ring resonator is assembled with a microfluidic channel placed below the ground plane. The near field of the complementary split ring resonator is sensitive to the electric permittivity of the fluid, which flows in the channel, therefore this setup can be applied as fluidic sensor. It is shown that the frequency shift of the first two resonances introduced by the complementary double split ring resonator can be utilized for sensing. The advantage of placing the microfluidic channel below the ground plane is that the guided electromagnetic wave can be well separated from the fluidic flow, which can simplify the measurement setup. The electromagnetic design of the sensor is discussed, and a prototype is presented. Simulations for different water temperatures reveals the sensitivity of the setup.

Double H-shaped complementary split ring resonator with different orientations for quad-band satellite applications

We experimentally studied the coupling between a double split ring resonator and a complementary split ring resonator. The greatest coupling occurs when the two resonators are separated by the average ring radius, and the dimensionless coupling is as large as 0.1, allowing a novel planar metamaterial based on this hybrid structure. The coupling strength can be varied up to a factor of 2 by changing the relative orientation of the split ring resonators. A 2×2 waveguide structure with -10 dB coupling factor can be achieved, and showing multi-mode plasmon-induced transparency. It can be considered one-dimensional metamaterials exhibiting negative permeability and permittivity simultaneously.

The development of highly sensitive, portable and low-cost sensors for the evaluation of ethanol content in liquid is particularly important in several monitoring processes, from the food industry to the pharmaceutical industry. In this respect, we report the optimization of two sensing approaches based on electrical impedance spectroscopy (EIS) and complementary double split ring resonators (CDSRRs) for the detection of ethanol in water. Miniaturized EIS sensors were realized with interdigitated electrodes, and the ethanol sensing was carried out in liquid solutions without any functionalization of the electrodes. Impedance fitting analysis, with an equivalent circuit over a frequency range from 100 Hz to 1 MHz, was performed to estimate the electric parameters, which allowed us to evaluate the amount of ethanol in water solutions. On the other hand, complementary double split ring resonators (CDSRRs) were optimized by adjusting the device geometry to achieve higher quality factors while operating at a low fundamental frequency despite the small size (useful for compact electronic packaging). Both sensors were found to be efficient for the detection of low amounts of ethanol in water, even in the presence of salts. In particular, EIS sensors proved to be effective in performing a broadband evaluation of ethanol concentration and are convenient when low cost is the priority. On the other end, the employment of split ring resonators allowed us to achieve a very low limit of detection of 0.2 v/v%, and provides specific advantages in the case of known environments where they can enable fast real-time single-frequency measurements.

Eine Schlüsselkomponente in einem optischen Netzwerk ist das optische Filter. Es gibt mehrere Arten von optischen Filtern, zum Beispiel Bragg - Gitter, Dünnschichtfilter, arrayed waveguide gratings (AWGs). Ein optisches Filter, dass in den letzten Jahren in der integrierten Optik hervorgetreten ist und welches in dieser Arbeit entworfen und untersucht wird auf der Basis von GaInAsP / InP, ist der Ringresonator. Filter auf der Basis von Ringresonatoren benötigen keine Spiegel oder Gitter für die optische Rückkopplung und eigenen sich deshalb hervorragend für die monolithische Integration mit anderen Komponenten wie z. B. Laser und Photodetektoren. Ein Filter mit einem benötigten bestimmten Transmissionsverhalten kann mit Hilfe mehrfach seriell oder parallel gekoppelter Ringresonatoren erreicht werden. ANFORDERUNGEN: Die Herstellung von Ringresonatoren in der integrierten Optik erfordert niedrig dämpfende, stark geführte Wellenleiter für die Realisierung kleiner Krümmungsradien (R ~ 100 µm). Abstimmbarkeit ist essenziell für die Systemanwendung von optischen Filtern. Im Fall periodischer Filter, in unserem Fall Ringresonatoren, ist es wichtig das Transmissionsverhalten des Filters an ein bestimmtes Kanalraster anzupassen (z. B. ITU - Raster). Die Filtereigenschaften passiver Ringresonatoren werden durch die internen Verluste eingeschränkt. Die Integration eines optischen Halbleiterverstärkers (SOA) ermöglicht nicht nur die Kompensation der internen Verluste, sondern auch zusätzliche Funktionalität (z. B. Schaltbarkeit). HERGESTELLTE BAUELEMENTE: Passive einfache Ringresonatoren und Doppelringresonatoren im Materialsystem GaInAsP / InP in der Form von Stadien, gekoppelt an Multimodeinterferenzkoppler (MMI) oder an Kodirektionalkoppler mit Radien von R = 100 µm - 200 µm und einem freien Spektralbereich (FSR) von 50 GHz und 100 GHz und On-Off Verhältnissen von mehr als 20 dB wurden realisiert. Einfache Ringresonatoren und Dreifachringresonatoren mit integrierten optischen Halbleiterverstärkern (Verstärkerlänge = 100 µm - 800 µm), gekoppelt an zwei Eingangs- und Ausgangswellenleiter unter der Verwendung von Kodirektionalkopplern mit Radien von R = 100 µm - 800 µm werden präsentiert. Die internen Verluste werden vollständig durch die Halbleiterverstärker ausgeglichen und On-Off Verhältnisse für den Durchgangskanal sowie für den Dropkanal von mehr als 20 dB wurden erreicht. Die Ringresonatoren besitzen einen freien Spektralbereich von 12,5 GHz, 25 GHz and 50 GHz. Die Abstimmbarkeit auf eine bestimmte Wellenlänge sowie die Resonanzanpassung der Doppel- und Dreifachringresonatoren konnte mit Hilfe von integrierten Platinwiderständen erreicht werden. Das Transmissionsverhalten hängt sehr von der stärke der Interaktion der beteiligten Ringresonatoren untereinander und mit den verwendeten Kopplern ab. Eine Designregel wird beschrieben um ein quasi rechteckiges Transmissionsverhalten durch Verwendung von Doppel- und Dreifachringresonatoren zu erreichen. Das Verhalten der hergestellten Bauelemente wird hinsichtlich ihrer Einfügedämpfung, Polarisationsabhängigkeit, Funktionalität und Einsatzmöglichkeit analysiert.

In this paper, a microwave polarizer based on frequency selective surface (FSS) loaded with complementary split ring resonator (CSRR) for non-planar and conformal application is presented. The frequency-selective polarizer is fabricated on liquid crystal polymer substrates (LCPs) material with $50\mu \text{m}$ thickness, which shows very good mechanical flexibility for microwave band. The Frequency-selective polarizer consists of a metal FSS screen pair with double complementary split ring resonators aligned in the vertical direction without any displacement. The substrate integrated waveguide (SIW) cavity was introduced to enhance the Q-factor of the CSRR particles and the mechanical strength of the FSS screens at bending conditions. The measured results show that the CSSR-FSS polarizer with the minimum transmission loss for TE-polarization incidence wave is 0.75dB at the 10.24 GHz and 19.05 dB for TM-polarization incidence wave, with an extinction ratio of 18.3dB. Finally, the oblique incidence from normal to 60 degrees and bending tests with the bending radius of 9.8 cm and 8.8 cm of the CSRR-FSSs were also carried out, and the measured results indicate that the CSRR-FSS show a low susceptibility to bending behavior at the small bending radius beyond the 8.8 cm and different incidence angles from normal to 45 degrees. Both the simulated and experiment data indicated that the proposed ultra-thin CSRR-FSS shows excellent flexibility and polarization selectivity.

A novel compact parallel-coupled line bandpass filter (BPF) with complementary split ring resonators (CSRRs) is presented in this letter.The proposed BPF, with a combination of CSRRs and parallel-coupled lines, has the advantages of compact size and simpler design procedure compared with conventional CRSS BPFs. The prototype filter achieves the measured insertion loss of 1.4 dB at 3.6 GHz. The implementing area is 0.35 λg × 0.14 λg, where λg is the guided wavelength at the resonant frequency. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:506–509, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27373

A four-element printed antenna array operating at 25 GHz frequency with complementary split ring resonator.
\n(CSRR) has been proposed for beamforming applications. The CSRR elements has been used to suppress the mutual coupling in the proposed array. The existence of the CSRR configuration in antenna array, controls the unnecessary surface current flow between the array elements, thus the mutual coupling between array elements has been significantly reduced up to -55 dB. The effect of mutual coupling on the array radiation patterns has been studied in the presence and absence of CSRRs. The effectiveness of CSRR has been studied by steering the main beam as well as the nulls in different angles. By implementing the CSRR elements in array antenna, the distorted array patterns have been recovered and are presented. The proposed antenna array with the CSRR has the advantage of easy and low-cost fabrication and it offers excellent coupling suppression without changing the antenna profile. The commercially available simulation tools such as Matlab and Ansys HFSS have been used for array weights calculation and antenna design respectively. Finally, the fabricated prototype has been experimentally verified, and it shows that the analytical and computed results agree well with the measured results.

In order to optimize the performance of the coupled resonator optical waveguide (CROW) gyroscope, a well-designed structure by optimizing the ring number and the transmission coefficient of the coupler is used as the core component of the planar waveguide optical gyroscope. The structure with double coupled ring resonator may possess large effective group refractive index to enhance angular sensing sensitivity was proposed. The concept of the Sagnac effect in this new double coupled ring resonator structure with a large effective group refractive index is investigated, it’s found that the rotation-induced phase shift is proportional to the effective group refractive index. On the basis of this effect, we calculate the general relation expression of theoretical rotation sensitivity and the effective group refractive index for this two-ring bidirectional CROW gyroscope by numerically simulation. Based on the relation, the phase shift characteristics of double coupled ring resonator and single ring resonator was analyzed. And the changing characteristics of the transmission coefficient of the couplers and the effective group refractive index was discussed based on the double cascaded ring resonator coupling mode theory. In the case of R1=R2=100 μm and ring transmission loss coefficient t1=t2=0.95, the generating condition of the largest effective group refractive index was obtained, according to the different effects of the couplers between rings and waveguide on the effective group refractive index. By using the parameters of R=100 μm and t=0.95, the sensitivity of a single ring resonator gyroscope is (104-105) °/h, and the sensitivity of double coupled ring resonator gyroscope can reach to 10 °/h. In summary, we show that the theoretical sensitivity of the double coupled ring gyroscope and single ring gyroscope are comparable when both have the same parameters. Using numerical and analytical methods, we demonstrated that coupling multiple resonators together can enhance rotation sensitivity. This research is important for applications of coupled ring resonator in optical angular velocity detection, and a promising regime to realize highly compact optical gyroscope.

A metamaterial unit cell based on double split ring resonator has been designed. The SRRs consist of a pair of concentric square copper rings. The metamaterial unit cell designed in millimeter scales. Effect of some geometric parameters of the split ring resonator such as the size of the gap, the width of the split ring resonator copper wires, the length of the inner ring and the length of the outer ring on the magnetic permeability has been investigated. The magnetic resonance frequency, the magnetic plasma frequency, the resonance bandwidth and the effective magnetic permeability at 9.5 GHz related to each metamaterial unit cell with specified geometric parameters has been calculated. Using these metamaterial unit cells, an invisible cloak operating in microwave regime is designed. The situation of the gaps in the double split ring resonator with two and four gaps is also changed and the effective permeability for each of them is obtained.

This chapter investigates the ability of the artificial materials to survive in the harsh high-power microwave (HPM) environment and lay the framework for considering the application of these materials in HPM devices. It utilizes the original Walser definition for a metamaterials (MTM); a subclass of artificial materials that exhibit both a simultaneous negative permittivity and permeability. The key configuration to realize MTM subwavelength geometries is the double split ring resonator (SRR) and wire array configuration mounted on a dielectric substrate. The chapter shows that MTMs based on SRRs suffer high losses dominated by dielectric losses in the substrate required to mechanically support the structure. Complementary split ring resonators are the all metal inverse images of the SRR. The chapter focuses on localized breakdown of an individual subwavelength elements, and the impact these localized defects would have on HPM device operation.

In this work, a low-cost double split complementary split ring resonator (CSRR) microwave sensor has been designed and fabricated on an FR4 substrate for permittivity characterization of liquids. This modified CSRR structure is proposed to make use of the benefits of the dielectric resonator technique compared to other types of microwave methods. The resonator structure comprises two slits in each of the rings normal to each other while maintaining one slit in each ring along the feed line for maximum excitation of the resonator. The resonator with substrate dimensions of 20mm×30mm acts like an inductance-capacitance-resistance (LCR) circuit and operates at 2.501GHz of the industrial scientific and medical band. Eleven different liquid samples (each with 150μl of volume) covering a wide permittivity range of 1−111 have been used to measure the transmission coefficient S21 using vector network analyzer. In comparison with many recently reported works, the sensitivity of the sensor is found to be higher with average and normalized sensitivity of 35.07MHz/unit permittivity and 1.4% respectively. Fit equations are developed for both real and imaginary parts of permittivity, and using the fit equations the permittivity of three unknown samples are determined with less than 3.7% error. The sensor adopts a unique orientation of the slits to enhance the E-field intensity for better interaction of the samples with the sensor. A compact form factor, low production cost, future integration possibilities, and high sensitivity are the distinct highlights of the sensor. The sensor promises to be a potential candidate for situations that demands low-cost and highly accurate measurements and may be a good alternative to commercial sensors for dielectric characterization, concentration analysis, and impurity measurement of liquids.

This paper investigated the effect of two main parameters of patch antenna by using partial ground techniques and addition of modified double W-shaped split ring resonator (MDW-SRR). The results show that these two techniques can be improving the performance of the return loss and bandwidth result of the patch antenna. The proposed antenna covers the frequency range of 1821.1 MHz to 3117.1 MHz with 1309.8 MHz of bandwidth compare to the normal antenna with only 33 MHz (2386 MHz to 2419.4 MHz). Firstly, the basic microstrip patch antenna design (Design A1) had been simulated in CST Microwave Studio simulation software. Secondly, the partial ground effect had been applied at the back of FR-4 substrate (Design A2). Then the Design B1, Design B2, Design B3 of four, eight and twelve units of modified double W-shaped split ring resonator (MDW-SRR) had been added into the patch antenna to compare its return loss, bandwidth, gain and directivity of the patch antenna.