Circular Patch Resonator Research Articles

Compact, wide-stopband filtering power divider based on a single shielded circular patch resonator

Compact, wide-stopband filtering power divider based on a single shielded circular patch resonator

Quad-band bidirectional metasurface microwave absorber with a patchwork of circular-patch resonators

In this paper, we present a straightforward design of a quad-band bidirectional metasurface microwave absorber (MMA) utilizing circular-patch resonators (CPRs). The MMA is comprised of tri-layer metal CPR structures separated by a dielectric substrate, which achieves perfect absorption due to the fundamental dipolar mode resonance in the CPRs structure. The absorption properties of the MMA can be adjusted by varying the radius of the CPRs structure. Moreover, we have demonstrated that strong absorption of the quad-band bidirectional MMA can be achieved by combining four CPRs with varying radii as a super unit-cell. Our simulation results reveal that the designed quad-band bidirectional MMA exhibits absorbance of 96.4%, 98.2%, 97.6% and 97.1% at 9.08 GHz, 10.07 GHz, 11.39 GHz and 12.95 GHz, respectively, which has been validated through experiments. Furthermore, the quad-band MMA maintains absorption stability under normal forward (+z) incident waves with different polarization angles for both transverse electric (TE) and transverse magnetic (TM) modes. Given its performance characteristics, the quad-band MMA may be an attractive option for potential applications in sensing, detecting, and communication.

A Simple and General Method for Cross-Coupled Bandpass Filters Based on Circular Patch Resonator

In this article, a simple and general method for the design of cross-coupled bandpass filters with compact size is proposed by virtue of the circular patch resonator. Owing to the unique symmetry of the circle, such a circular patch resonator can be freely divided into several circular sector patch resonators along the radii. With this transformation, any two of the divided resonators have a possible coupling region. Specifically, the neighboring resonators have adjacent sides, while the vertices of all resonators are gathered in the center. Given this, the cross couplings can be easily constructed. Moreover, as the circular sector patch resonators with different boundary conditions along two sides have associated resonant properties, both positive and negative couplings can be provided. Consequently, the circular patch resonator should be a good candidate for the design of cross-coupled filters, and the concrete layout of the resultant filter can be determined by the design parameters as extracted from the design specifications. For demonstration, four design examples, including two single-band, one dual-band, and one tri-band bandpass filters, are constructed, fabricated, and measured. All measured results are in good accordance with the synthesized and simulated counterparts, thereby satisfactorily validating the feasibility and universality of the proposed design method.

Design of Filtering Coupler Based on Patch Resonator with High Selectivity

In this paper, a new approach for designing a planar high frequency selectivity filtering coupler based on a circular patch resonator is proposed. In order to explain the operating principle, the resonant property of the circular patch resonator has been investigated firstly. Two circular patch resonators connected by two microstrip lines are used in this design. A filtering coupler is achieved by adjusting the feeder position and the length and width of the microstrip line used to connect the two resonators. Without additional circuits, the desired 0° and 180° phase differences are realized by the inherent in-phase and out-of-phase characteristics of E-fields at the TM11 mode. To improve the passband selectivity, transmission zeros are created by introducing a coupling between the source and load through the coupling slots etched on the ground. Finally, a prototype of the filtering coupler centered at 2.12 GHz is designed, implemented, and tested, while the measured results coincide well with simulated ones, verifying the proposed design concept.

Determination of a Measurement Procedure for the Study of Cells' Dielectric Properties through Descriptive Statistic.

This paper presents a measurement procedure for analyzing the dielectric properties of cells using descriptive statistics. The study focuses on four cancer cell lines (MDA-MB-231 and MCF-7 breast cancer, SaOS-2, and 143B osteosarcoma) and DMEM culture medium, utilizing the Lorentzian fit model of the return-loss function. The measurements are performed using a circular patch resonator with a 40 mm diameter, powered by a miniVNA operating in the frequency range of 1 MHz to 3 GHz. Eight specimens are prepared for each group to ensure reliability, and the return loss is recorded ten times for each specimen. Various statistical parameters are calculated and evaluated, including the average value, standard deviation, coefficient of variation, and relative error between the average and the first values. The results demonstrate that one single acquisition highly represents the entire set of ten data points, especially for the resonant frequency, with an accuracy error lower than 0.05%. These findings have significant implications for the methodological approach to detecting cells' dielectric properties, as they substantially reduce time and preserve the specimens without compromising the accuracy of the experimental results.

A Principal Componet Analysis to detect cancer cell line aggressiveness

In this paper, we propose the use of Principal Component Analysis (PCA) as a new post-processing method for the detection of breast and bone cancer cell lines cultured in vitro using a microwave biosensor. MDA-MB-231 and MCF7 breast cancer cell lines and SaOS-2 and 143B osteosarcoma cell lines were characterized using a circular patch resonator in the 1 MHz – 3 GHz frequency range. The return loss of each cancer cell line was analyzed, and the differences among each other were determined through Principal Component Analysis according to a protocol previously proposed mainly for electrocardiogram processing and X-ray photoelectron spectroscopy. Our results showed that the four cancer cell lines analyzed exhibited peculiar dielectric properties when compared to each other and the growth medium, confirming that PCA could be employed as an alternative methodology to analyze microwave characterization of cancer cell lines which, in turn, may be deeply exploited as a tool for the detection of cancer cells in healthy tissues.

Characterising nematic liquid crystals using a circular patch resonator

ABSTRACT Reconfigurable microwave material is a promising candidate for designing and manufacturing tunable microwave components. Nematic liquid crystals (NLC) are such materials since their permittivity can be tuned by an external electric field. However, many NLC mixtures were not properly characterised at higher frequency bands due to requiring a complex measurement setup. In this work, a novel method using circular patch resonator (CPR) is developed to measure the dielectric constant and loss tangent of NLCs at microwave frequencies. In addition to using the cavity model for the preliminary design and analysing the fringing effect for a better accuracy, full-wave simulations are employed to confirm the final design and aid the characteristic analysis. Three prototypes were fabricated and measured to reduce uncertainty from manufacturing defects. To avoid the possible damage when higher voltage is required for a large range tuning, a coupling mechanism is proposed between the microstrip line and coplanar waveguides (CPWs) to replace connection through vias. A high accuracy with an uncertainty of 0.02 for relative permittivity estimate has been demonstrated with experiment verification, approximate 80% improvement than other typical methods. The simple design and PCB-based manufacturing techniques can be widely employed to characterise the properties of newly-developed LC mixtures.

A Novel Microwave Resonant Sensor for Measuring Cancer Cell Line Aggressiveness.

The measurement of biological tissues’ dielectric properties plays a crucial role in determining the state of health, and recent studies have reported microwave biosensing to be an innovative method with great potential in this field. Research has been conducted from the tissue level to the cellular level but, to date, cellular adhesion has never been considered. In addition, conventional systems for diagnosing tumor aggressiveness, such as a biopsy, are rather expensive and invasive. Here, we propose a novel microwave approach for biosensing adherent cancer cells with different malignancy degrees. A circular patch resonator was designed adjusting its structure to a standard Petri dish and a network analyzer was employed. Then, the resonator was realized and used to test two groups of different cancer cell lines, based on various tumor types and aggressiveness: low- and high-aggressive osteosarcoma cell lines (SaOS-2 and 143B, respectively), and low- and high-aggressive breast cancer cell lines (MCF-7 and MDA-MB-231, respectively). The experimental results showed that the sensitivity of the sensor was high, in particular when measuring the resonant frequency. Finally, the sensor showed a good ability to distinguish low-metastatic and high-metastatic cells, paving the way to the development of more complex measurement systems for noninvasive tissue diagnosis.

A novel dual‐band balanced‐to‐single‐ended in‐phase filtering power divider based on slotted circular patch resonator

This article proposes a balanced-to-single-ended (BTSE) in-phase filtering power divider (FPD) based on slotted circular patch resonator, By carefully studying the TM11-like and TM12-like modes in the slotted circular patch resonator, the common-mode (CM) signal of the balanced port can be well suppressed, and in-phase output and good isolation can be obtained at the single-ended ports. At the same time, two patch resonators is properly coupled through the apertures etched on the common ground in a back-to-back form to achieve a dual-band filter response. In order to verify the feasibility of this concept, a dual-band BTSE in-phase FPD operating at 3.9 and 7.3 GHz is designed, manufactured and tested. The simulation results are in good agreement with the measurement ones, indicating that the design has expected differential-mode (DM) response, nice CM rejection, significant single-ended output port isolation, and a dual-wide frequency band.

Ultra-broadband terahertz metamaterial absorber using a simple design method

Using a simple design method cutting away some parts of a circular metallic patch resonator, we propose an ultra-broadband terahertz metamaterial absorber (MA) with bandwidth of 4.11 THz. Simulation results demonstrate that the simple design method greatly improves the absorption performance compared with previously reported absorbers. The proposed absorber exhibits the co-polarization ultra-broadband absorption performance with absorptivity above 90% in the range of 2.65–6.76 THz and the relative absorption bandwidth (RAB) of 87.35%. Moreover, the proposed absorber can maintain high absorptivity above 80% for incident angles up to 40° under both transverse electric (TE) and transverse magnetic (TM) polarizations. The ultra-broadband absorption originates from the combination of dipolar and LC resonances. The simple design method can also be applied to some other structures such as square metallic patch resonator. Furthermore, by adjusting the dimensions of proposed absorber, a broadband microwave MA can be easily obtained. Therefore, it can become an effective design method to achieve broadband absorption in various frequency ranges from microwave to optical frequencies.

Design and analysis of circularly polarized circular patch antenna with multiple shorting pins using characteristic mode theory

In this paper, we design a single-layer single-feed Circularly Polarized (CP) circular patch antenna with loading of shorting pins. At first, metallic pins are symmetrically placed in a circular patch resonator, and a characteristic mode analysis is carried out. Then, current distributions are studied for a circular patch with four shorting pins, and the pins are slightly shifted to excite two orthogonal degenerate modes simultaneously for CP wave radiation. Finally, the CP circular patch antenna with four shorting pins and optimal feed position is designed to enhance the antenna gain. The proposed antenna has a compact size with dimensions of 0.49λ 0 × 0.49λ 0 × 0.0147λ 0 at 2.76 GHz. According to this study, we can determine the best place of the pins for obtaining the circular polarization. The return loss and radiation properties are measured and compared with simulation results. The proposed antenna has a 3 dB axial ratio bandwidth of 1.8% (2.73–2.78 GHz). The measured gain is 6.1 dBic at 2.76 GHz. The importance of this study is that we can predict the behavior of the antenna with a different number of shortening pins for defining the resonance frequency and obtaining circular polarization.

Design of a New Dual-Band Balanced-to-Balanced Filtering Power Divider Based on the Circular Microstrip Patch Resonator

A novel compact dual-band balanced-to-balanced (BTB) filtering power divider (FPD) based on the circular microstrip patch resonator is presented, for the first time in this brief. Firstly, in order to elucidate its principle of operation, the resonant property of the circular microstrip patch resonator is researched. After that, a prototype of the dual-band BTB FPD is developed. It is mainly constructed by two coupled circular patch resonators, two impedance matching ports, and three pairs of balanced ports. Its operating mechanism can be strictly illustrated by the field distributions of the concerned resonant modes. Hereinto, desired dual-band balanced filtering response is attained by elaborately exploiting TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> and TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">31</sub> modes while suppressing other modes from the patches. Ultimately, for validation, a dual-band BTB FPD centered at 4.2 GHz and 9.4 GHz is designed, fabricated, and tested. Good agreement between simulated and measured results validates that expected differential mode (DM) response, prominent DM isolation, nice common-mode (CM) suppression, high selectivity, and satisfactory harmonic suppression.

Dual-Band Filtering Power Divider Based on a Single Circular Patch Resonator With Improved Bandwidths and Good Isolation

In this brief, a novel compact single circular patch dual-band (DB) filtering power divider (FPD) is proposed for the first time. In this design, the modified TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">01</sub> resonance mode (i.e., TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">01</sub> ’ mode) is developed by introducing a metallic via in the center of the patch, while four additional same metallic vias are placed in the patch to control the generated TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">01</sub> ’ mode and the TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">21</sub> mode. In addition, vertical slot perturbations are investigated to control the TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> mode and the TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">31</sub> mode, while the transversal slot perturbation loaded with three resistors is exploited to achieve good isolation. In this context, with elaborate exploitation of these resonant modes, two passbands can be attained, correspondingly. The lower passband is formed by TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">01</sub> ’ and TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> modes, while the upper passband is constituted by TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">21</sub> and TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">31</sub> modes, respectively. For validation, a prototype is implemented. Results exhibit relative compact size, wider bandwidths, nice return losses, as well as decent isolation.

A new balanced‐to‐single‐ended in‐phase filtering power divider based on circular patch resonator with good isolation and wide stopband

In this article, a novel balanced-to-single-ended (BTSE) in-phase filtering power divider (FPD) based on circular patch resonator with good isolation and wide stopband is proposed. In this design, by carefully exploring the electric field distributions of the microstrip circular patch resonator modes, the common-mode can be well suppressed at the balanced ports, while in-phase output and good isolation can be attained at the single-ended ports. At the same time, filtering response is formed by coupling two circular patches through a circular aperture etched on the common ground. To verify the feasibility of this concept, a BTSE in-phase FPD operating at 4.2 GHz with 3-dB fractional bandwidth (FBW) of 19% is designed, manufactured, and tested. The consistency between the simulation results and the measurement results is good, indicating that this design has expected differential-mode response, nice common-mode suppression, significant single-ended output port isolation, as well as wide stopband.

Design of a Multilayer Dual-Band Balanced Bandpass Filter on a Circular Patch Resonator

This letter presents a novel multilayer dual-band balanced bandpass filter (BPF) design by using two perturbed circular patch resonators. The TM11 mode and TM21 mode of the resonator with odd-symmetric field distributions are explored to realize the desired differential-mode (DM) transmission and common-mode (CM) suppression. Two circular patches are properly coupled in the back-to-back form to realize a dual-passband balanced response by virtue of coupling apertures etched on the ground. In addition to the internal coupling, the above apertures are also further utilized for the undesired degenerate mode harmonic suppression. Besides, slot perturbations on the patch are introduced to perturb the TM21 resonant mode to independently adjust the center frequency of the higher passband, while the lower passband remains almost unchanged. Thus, two passbands can be flexibly controlled by simultaneously tuning the above slots and size of the patch. For validation, a dual-band balanced BPF prototype is implemented. The results indicate 18 and 26% wide fractional bandwidths centered at 5.5 and 7.5 GHz with return loss higher than 20 dB under DM operation and CM suppression higher than 40 dB over an ultra-wide frequency band.

Triple‐mode bandpass filter based on short‐circuited patch resonator

The letter presents a triple-mode short-circuited circular patch resonator for bandpass filter (BPF) design. The resonator employs the TM010 mode as its dominant mode, the resonant frequency of which is lower than that of the TM110 mode. In addition, four radial slots are etched on the patch to extend the current paths of the TM110 and TM210 modes, shifting down the resonant frequencies of the two modes. The adjacent triple modes can be used to design wideband BPF. Meanwhile, the centre frequency (CF) and bandwidth (BW) can be tuned by the length of the slots. Furthermore, the short-circuited vias are arranged in a circle providing a tuneable parameter to control the CF and BW as well. According to the symmetry of the geometry, the resonator can be bisected to realise half-mode resonance. Two cascaded half-mode semi-circular patch resonators are applied to design BPF with high selectivity. BPFs using the circular patch resonator and the semi-circular patch resonator are designed and measured for demonstration.

Design of wideband/dual‐band bandpass filter using a vias and slots loaded sector circular patch resonator

Design of wideband/dual‐band bandpass filter using a vias and slots loaded sector circular patch resonator

Novel balanced single/dual‐band bandpass filters based on a circular patch resonator

Novel balanced single/dual‐band bandpass filters based on a circular patch resonator

Miniaturized dual‐mode sector patch bandpass filter using a single via‐hole

AbstractA miniaturized dual‐mode sector patch bandpass filter using a single via‐hole is presented in this article. Only a single 11.25° sector patch resonator, which is one‐thirty‐second of the complete circular patch resonator, is utilized to miniaturize the filter for the first time. Without changing the size and construction of the initial patch, a simple via‐hole is used to perturb the patch resonator, thus the novel dominant mode, which provides further compactness is generated. In addition, the change of via‐hole position is utilized to expand the bandwidth and significantly enhance the flexibility of the filter. Moreover, the proposed filter possesses two transmission zeros and it has obvious advantages of low insertion loss, compact size, and wide passband.

Design of wideband bandpass filter using short‐circuited circular patch resonator loaded with slots

Design of wideband bandpass filter using short‐circuited circular patch resonator loaded with slots