Annular Microstrip Research Articles

Compact Design of Annular-Microstrip-Fed mmW Antenna Arrays.

In this paper, a series of four novel microstrip antenna array designs based on different annular-microstrip feeding lines at 60-GHz millimeter wave (mmW) band are proposed, aiming at the potential usage of the mmW coverage antenna with multi-directional property. As the feeding network, the annular contour microstrip lines are employed to connect the patch units so as to form a more compact array. Our first design is to use an outer contour annular microstrip line to connect four-direction linear arrays composed of 1 × 3 rectangular patches, thus the gain of 8.4 dBi and bandwidth of over 300 MHz are obtained. Our second design is to apply the two-direction pitchfork-shaped array each made up of two same linear arrays as the above, therefore the gain of 9.65 dBi and bandwidth of around 250 MHz are achieved. Our third design is to employ dual (inner and outer contour) annular-microstrip feeding lines to interconnect the above four-direction linear arrays, while our fourth design is to bring bridged annular-microstrip feeding lines, both of which can realize the goal of multi-directional radiation characteristic and higher gain of over 10 dBi.

Performance analysis of circularly polarized dual annular ring patch antenna for MIMO satellite application

ABSTRACT In this paper, a dual annular ring patch antenna with high isolation for Multiple Input Multiple Output (MIMO) Satellite application at 4 GHz is presented. The mutual coupling reduction and circular polarization are achieved by some perturbations in annular ring patch and microstrip stubs between antennas. These perturbations will excite two modes which is orthogonal ie. equal amplitude and phase shift to make it circularly polarized. The antenna design is fabricated on a substrate with permittivity 4.4 and 1.6 mm thickness. The simulated results are studied and analyzed for the proposed antenna. The isolation of better than 30 dB, axial ratio lower than 3 dB and gain of about 3.4 dB are obtained. The performance characteristics are simulated, measured and analyzed with different antenna parameters. The validated antenna shows that the simulated and measured results are in good agreement with each other.

Modeling and analysis of microstrip annular ring antenna with capacitive coupling matching network

In this manuscript, microstrip annular ring antenna with capacitive coupling matching network is modeled and analyzed with equivalent circuit model and cavity model, which is simple and accurate for this structure. The proposed approach not only demonstrates physics lying behind the engineering design but also will be a good guideline for the microstrip annular ring antenna design. A prototype working UHF RFID band (902-928 MHz) is designed. Overall dimension of the proposed antenna is about 0.5λ0 × 0.5λ0 × 0.055λ0, and the realized gain is larger than 5 dB with axial ratio is smaller than 3 dB. The measured results agree well with simulated counterparts except slightly frequency shift.

Boxed Ring Resonator for Liquid Dielectric Constant Measurement

The present study describes a compact and low-cost microstrip based resonant sensor that is specially developed for measurements of dielectric constant for liquid and paste at a frequency of 2.45GHz. The sensor utilizes shielded, boxed microstrip annular ring resonator structure, enabling a simple method to place a sample of liquid to be measured. The Transmission Line Model (TLM) of the multilayer system is successfully developed. The inverse algorithm is used to calculate real (e’) and imaginary parts (e”) of the permittivity for the liquid sample with the inputs of the changes in the resonant frequency (fr) and the quality factor (Q). Experimental data is testified against the related theory and compared with the results obtained by other researchers. CST MWS simulation software is used for the optimization of the boxed annular ring and concentric ring resonator structure. The comparison is done for the annular ring and concentric ring resonator boxed structure. Annular ring resonator structure has better accuracy than concentric ring resonator structure. This measurement system indicates high potential towards the development of a portable technique for quality analysis of liquids.

Wearable antenna with tripolarisation diversity for WBAN communications

A wearable antenna with tripolarisation diversity is designed for wireless body area networks (WBANs). The antenna is fabricated with flexible materials. Three polarisations are realised by combining an inductive loaded circular monopolar patch antenna with a microstrip annular ring antenna. Simulated and measured results show that the antenna has sufficient bandwidth for a WBAN. The port isolation reaches 13.5 dB, and the correlation coefficients show a good diversity performance.

Reconfigurable microstrip annular ring antenna for circular polarization diversity

ABSTRACTThis article presents a novel design of a microstrip annular ring antenna with reconfigurable circular polarization (CP) diversity by switching one corner perturbation segment. The proposed antenna has a construction of a single‐feed annular ring as a radiator and frequency perturbing elements at one diagonal edge. To achieve the condition with left‐ and right‐handed CP diversity, the perturbations of the proposed antenna uses the concept of positively and negatively slot‐loaded annular ring. By controls of two diodes' states in the perturbation, both of CP senses have been easily alternated. The simulated and measured results show good and symmetrical radiation patterns at each resonant frequency. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1706–1709, 2014

Frequency adjustable microstrip annular ring patch antenna with multi-band characteristics

This study introduces a frequency-tunable dual-band microstrip annular ring patch antenna design for wireless local area network (2.45 GHz) and Worldwide Interoperability for Microwave Access (3.5 GHz) applications. The proposed antenna produces realisable gain higher than 5 dBi and return loss better than 10 dB for the stated applications. The antenna design consists of an annular ring patch loaded with a slot or gap. This loaded ring excites higher-order modes around the dominant mode (TM11) of the annular ring thus making this design capable of dual-band operation. This design is realised on a 1.57 mm thick polytetrafluoroethylene substrate using a coaxial probe feed. In this study, a novel technique for independent frequency tuning has also been introduced by cutting grooves on the periphery of the ring at the desired locations. Furthermore, the design capability of multi-band operation (2.45 GHz/3.5 GHz/5.5 GHz) has also been explained in the later part of the study. Antenna operation has been verified with the help of two commercially available EM solvers (CST Microwave Studio and Ansoft HFSS Designer) and measurements. A close agreement has been found between the simulated and the measured results.

Microwave Permittivity and Conductivity of Leaf Using Film Microstrip Annular Ring Antenna

Microwave Permittivity and Conductivity of Leaf Using Film Microstrip Annular Ring Antenna

Polarization Characteristics of Multiband Loaded Microstrip Annular Ring Antennas

Multifrequency operation can be obtained from the single-layer probe-fed annular ring antenna by loading it with a gap or slit. Two types of loading are studied: vertical and horizontal gap. For each case, two unloaded modes are excited around the dominant TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> mode of the ring, equally spaced on the frequency spectrum. These multiple modes are excited, when the loading is symmetric on one side of the ring along one axis, and the excitation is off-centered on another side, or vice-versa. By choosing the location of the vertical or horizontal gaps along the <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">y</i> - or <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</i> -axis respectively, the polarization of each mode can be controlled. One of the loaded mode frequencies is much lower than the dominant TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> mode frequency of the annular ring, indicating a miniaturization of antenna to a great extent. Effects of substrate parameters are investigated on the loaded and unloaded mode frequencies, and a design guideline is presented. Simulation results are confirmed by measurements.

On the Use of Subsectional Spline Basis Functions for Efficient Calculation of the RCS of a Microstrip Array of Concentric Annular Rings Over a Wide Frequency Band

The use of B-splines in the radial direction is described for efficient calculation of the radar cross section (RCS) of a microstrip annular ring or array of concentric annular rings, over a wide frequency band. Galerkin's method in the vector Hankel transform (VHT) domain is used to calculate the induced current density on the annular patches. An algorithm is presented for a fast and accurate calculation of the scalar Hankel transforms of B-splines on an arbitrary nonuniform grid, which plays an important role in the numerical calculation of the reaction integrals containing the scalar Hankel transforms of B-splines. The accuracy and computational efficiency of the method and the convergence of the RCS results with respect to the number of segments along the radial direction are studied for some annular ring and concentric ring patches.

Theoretical investigations of an annular elliptical ring microstrip antenna using Green's function technique

Analytical expressions for the Green's function of an annular elliptical ring microstrip antenna (AERMA) are developed and reported. The modal, radiation and input impedance characteristics of the TM/sub nm/ modes are determined from these expressions. The resonant frequencies of odd modes are greater than that of the even modes for all TM/sub nl/ modes (n=1, 2, 3,...) unlike elliptical microstrip structures. The radiation pattern and input impedance curves of the TM/sub 12/ mode, on comparison with available experimental results, show good agreement which provides an independent validation to this technique. The performance of the AERMA is then investigated as a function of thickness and substrate dielectric permittivity.

An improved method to analyze the input impedance of microstrip annular-ring antennas

The problem of microstrip annular-ring patch antenna excited by a probe is solved using rigorous analysis. Minimal assumptions, except the uniform current distribution on the probe and zero thickness of the patch have been made in our analysis. By using the vector Hankel transforms, the problem is formulated in terms of vector dual-integral equations, from which the surface current on the patch can be solved for. The singular part of the current arising from the probe feed is extracted from the expansion series in order to accelerate convergence. It is shown that this analysis agrees with the single mode approximation (SMA) method when the substrate layer is thin, while it deviates from the SMA method drastically when the substrates become thick. Experimental results show that the analytical procedure used in this paper can greatly improve the accuracy of the computed input impedance of microstrip annular-ring patch antenna.