Single Circular Patch Research Articles

A Compact Ultra-Wideband Millimeter-Wave Four-Port Multiple-Input Multiple-Output Antenna for 5G Internet of Things Applications.

This paper presents a compact design for a four-element multiple-input multiple-output (MIMO) antenna for millimeter-wave (mmWave) communications covering the bands of n257/n258/n261. The MIMO design covers the frequency range of 24.25-29.5 GHz, with a wide bandwidth of 5.25 GHz. The element of the MIMO antenna structure uses a single circular patch with an inset feed, and, in order to improve the reflection coefficient (S11), a half-disk parasitic patch is positioned on top of the circular patch. Moreover, to fine-tune the antenna's characteristics, two vertical stubs on the extreme ends of the ground plane are introduced. For this design, a Rogers RT/Duroid 5880 substrate with ultra-thin thickness is used. After the optimization of the design, the four-port MIMO antenna attained a tiny size, with the dimensions 16.2 mm × 16.2 mm × 0.254 mm. In terms of the MIMO parameters, the ECC (Envelop Correlation coefficient) is less than 0.002 and the DG (Diversity Gain) is greater than 9.99 dB in the mentioned band, which are within the tolerance limits. Also, in spite of the very small size and the four-port configuration, the achieved isolation between the neighboring MIMO elements is less than -23.5 dB.

Multiband Metasurface‐Based Absorber for Applications in X, Ku, and K Bands

AbstractIn this paper, a slotted‐circle patch metasurface that can efficiently absorb electromagnetic (EM) waves in three different bands is proposed. Based on the fundamental resonance of a single circular patch, EM resonances are generated making slits in the circular patch leading to multi‐band operation. Simulation results show that the proposed structure can absorb signals in three different bands, namely at 8.10, 15.39, and 19.7 GHz with absorption peaks of 99.8%, 99.7%, and 99.8%, and absorption bandwidths of 132, 181, and 90 MHz, respectively. The absorption mechanism is discussed on the basis of the single‐layer effective medium model and the analysis of surface current and electric field distributions. Furthermore, the experimental results show good agreement with the numerical simulations, with an average absorption greater than 99%. The 2‐mm thick absorber is electrically thin, corresponding to ∼λ/18 at its lowest operating frequency. Compared to other published designs, the proposed absorber has a single resonator with simple geometry, but operates in multiband. Therefore, it can be used in many applications such as anechoic chambers, scattering control, photodetectors, microbolometers, and solar cells. The proposed metasurface absorber can be used for microwave energy harvesting as well as sensor and radar cross‐section reduction applications.

Design of a High-Gain Single Circular Patch Radiator With a Cavity-Backed Structure Using Multiple SIW Feeders for Monopulse DF-Applications

This paper proposes the design of a gain enhanced single circular patch radiator (SCPR) with a cavity-backed structure using multiple substrate integrated waveguide (SIW) feeders for monopulse systems. We derive the equations of a radiation pattern for the multi-feed SCPR and compare it with the full EM simulation results. Based on the theoretical results, the proposed SCPR with multiple feeds is designed by adding the cavity-backed structure to obtain high gain characteristics. In the feeding network, four SIW structures are designed and circularly arranged, which can reduce loss and mutual coupling. Each pair of the SIW feeders can provide sum ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Sigma$ </tex-math></inline-formula> ) and difference ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Delta$ </tex-math></inline-formula> ) patterns to achieve the monopulse direction finding (DF) properties in both elevation and azimuth directions. To verify the feasibility, the proposed antenna is fabricated, and the antenna characteristics are measured. The measured reflection coefficient is −14.5 dB at 5.8 GHz, and the maximum gains are 4.9 dBi and 4.8 dBi in <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">zy</i> -plane. To observe the monopulse DF, the estimated direction of arrival (DOA) results are examined in both elevation and azimuth directions. In the whole estimated angle range, the estimation error is lower than 0.49, and the average error is 0.26.

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.

Dual‐band filter based on one single circular patch resonator with highly improved bandwidths and compact size

In this Letter, a new design of dual-band patch filter is proposed with greatly improved bandwidth and miniaturised size based on one single modified circular patch resonator. In this design, a metallic via is introduced in the centre region of the patch to develop the modified resonant TM01 mode (TM′01 mode), while two types of slot perturbations are adopted to separate a pair of degenerate modes of TM11 (TM11A and TM11B) and control another pair of degenerate modes of TM21 (TM21A and TM21B), respectively. Thus, two passbands with one transmission zero (TZ) can be attained by elaborately exploring these resonant modes (the TM′01 and TM11A modes form up the lower passband while TM11B and TM11A modes constitute the upper passband, and TM21B mode is responsible for the TZ). For verification, one prototype is implemented. Results indicate that the novel dual-band filter (centred at 3.7 and 5.3 GHz) exhibits not only relative compact size (0.36 λ g × 0.36 λ g), but also much larger 3-dB fractional bandwidths (27 and 13%), nice return loss (better than 21 dB) and insertion loss (better than 1.0 dB), compared with other reported patch filters.

Graphene Based Circular Shaped Micro Strip Patch Antenna Array for 2.45 GHz ISM Band Application

Graphene based circular microstrip patch antenna array is presented in this paper. First a single circular patch to resonate at 2.45 GHz is designed in HFSS, then 1 × 2 array and 1 × 4 array are developed in order to improve the gain. The designed patch and arrays are fabricated using copper and graphene and the antenna parameters are measured and compared. This research work mainly focuses on two things; one is to improve the gain by developing array and the other one is to develop graphene antenna array using a simple, low cost printing method. Both are achieved, as the gain is improved by ~ 5 dB for 1 × 4 array when compared to single patch and the graphene antenna is fabricated and tested for its performance and found to be working perfectly as antenna in ISM Band.

Optimization of Directivity and Gain Performances on Circular Patch Antenna Design for 2.4 GHz Applications

In this paper, simulation and optimization analysis on circular patch antenna for 2.4GHz is presented. The performance that been specifically focused in this analysis is the improvement of the directivity and gain of the circular patch antenna design. Basically, the objective of this analysis is to compare the circular patch antenna of a single form with 1x2 antenna array formation. These antennas are designed with the proximity feeding technique. From the previous literature and findings, the optimization works of array arrangement have been proven will improve the directivity and gain performances. In this study, the array arrangement with proximity feeding technique of optimization work to improve the directivity and gain of a circular patch antenna has been explored. Comparison of a single and array of micro strip circular patch with proximity feeding technique as the FR-4 is the substrates with permittivity equal to 3.95 is presented. Based on the results, 1x2 array arrangements enhance the directivity and gain output compared to a single form circular patch antenna design. The directivity performance improves 28% and gain has been improved by 47% after optimization. The findings show that the array elements with proximity feeding technique design offer to improve and enhance the directivity and gain performances of an antenna.

A Low-Profile Antenna With Omnidirectional and Unidirectional Radiation Patterns Over Two Operation Bands

A compact low-profile dual-band antenna with a single circular radiation patch is presented. The circular radiation patch is top-loaded by a metal strip, leading to a zeroth-order resonant (ZOR) mode with monopole-like radiation pattern at the lower operation band, and the ZOR mode is not affected by the position change of the probe feed. Thereby an off-center probe feed can be used to excite a TM01 mode with patch-like radiation pattern at the upper operation band, and its performance remains good stability when the size of the metal strip is varying. The equivalent circuit, electric field and current distributions of the proposed antenna are studied to investigate the principles of the ZOR and the TM01 modes, and all the results show that the two operation bands can be effectively and independently controlled. As a proof-of-concept, a circular patch antenna prototype with low profile of about $0.023~\lambda _{0}$ at 2.35 GHz is fabricated and tested. Good agreements between the measured and simulated results are achieved, showing monopole-like and patch-like radiation patterns within 2.28 - 2.40 GHz and 3.30 - 3.60 GHz, respectively, and the average realized gains are about 2.5 dBi and 8.5 dBi for the two operation bands.

Wideband Dual-Mode Patch Antenna With Compact CPW Feeding Network for Pattern Diversity Application

A wideband microstrip patch antenna is proposed in this communication for pattern diversity application. Broadside and omnidirectional radiation patterns are generated by the odd and even modes of a single circular patch. A compact feeding network based on coplanar waveguide is designed to provide in-phase and out-of-phase excitations, which can excite the two modes in wide bandwidth. The size of the feeding network is only $35 \times 14.5$ mm2. A prototype of the proposed antenna is fabricated and tested. The measured overlapped bandwidth ( $\vert \text{S}_{11}\vert dB and $\vert \text{S}_{22}\vert dB) achieves 775 MHz (2.165–2.94 GHz) or 31% corresponding to the center frequency. The Port isolation is below −28 dB in the entire bandwidth.

A novel compact dual‐band dual‐polarized microstrip patch antenna for GSM/DCS applications

ABSTRACTIn this paper, a novel compact dual‐band dual‐polarized microstrip stacked patch antenna suitable for base stations is presented. The first and second frequency bands cover the GSM and DCS bands respectively. The antenna layout consists of a single circular patch with four symmetrical slots along its periphery mainly responsible for the upper frequency band and one cross‐shaped slot at the center, mainly responsible for the lower one. The stacked configuration is considered for bandwidth enhancement. The antenna utilizes a simple orthogonal feed network for the two polarizations, which feeds the patch through a relatively wide cross‐shaped slot at the antenna's ground plane, placed centrally with respect to the patch. The antenna bandwidth completely covers the two desired bands with relatively good return loss and also exhibits polarization isolation of greater than 33 dB and 40 dB in the lower and upper frequency bands respectively. In addition, the antenna has good radiation characteristics in terms of cross‐polarization in both bands of interest. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:2557–2559, 2016

UWB MIMO antenna with common radiator

A compact printed 2 × 2 ultrawideband (UWB) multiple input multiple output (MIMO) antenna with a single circular patch as a common radiator for both the antenna elements is presented in this paper. A single circular patch is excited by two tapered CPW feeds for dual polarization. To improve the isolation between two ports, a rectangular slot of dimension L1 × W1 is created in the radiator. The UWB MIMO antenna has impedance bandwidth of 3–12 GHz with a isolation better than 17 dB between the two ports. The envelope correlation coefficient and the capacity loss are evaluated to ensure the good diversity performance of UWB MIMO antenna. The antenna has a compact size of 45 × 45 mm2 and is fabricated on low cost FR4 substrate and measured using Agilent VNA. The simulated and measured results show that the proposed UWB antenna is good candidate for UWB MIMO applications.

Single and Multiband UWB Circular Patch Antenna for Wireless Communication Applications

This paper presents the design of an ultra-wide band (UWB) circular patch antenna with microstrip line feed and optimization of various antenna parameters. The antenna with dimension of (33 x 30 x 1.5) mm3 is fabricated on FR-4 epoxy substrate having permittivity constant er=4.3, loss tangent tanδ=0.002. The designed antenna has the capability of operating in the bands (2.7-4) GHz, (6.8-12.5) GHz and (14.6-18) GHz. The antenna performance was modified by inserting a slot in the ground plane to achieve impedance bandwidth (S11<-10dB) in (2.7-20) GHz. The modified antenna was fabricated and tested using the vector network analyzer. The simulated and measured results are presented and compared. The feed line used has characteristic impedance of 50Ω.

Comparative Analysis of a Circularly Polarized Microstrip Antenna with a Cross-Slot using Single and Double Substrate

This paper compares the different parameters for differently configured single substrate circular patch and double substrate square patch microstrip antenna. The proposed antenna 1 is fed by proximity coupled feed whereas the proposed antenna 2 is single fed to excite the antenna. Copper clad substrate is used in this design. The circular polarization is achieved by the proposed antennas without 90° hybrid coupler. The proposed antennas are applicable for L and S band applications (1.26GHz and 2.56/2.65 GHz respectively). The gain of both of the antenna are approximately same. This comparison will provide the technique for miniaturization using single substrate.

Dual-Mode Dual-Band Bandpass Filter Using a Single Slotted Circular Patch Resonator

A single slotted circular patch resonator is proposed in this letter to design a novel dual-mode dual-band bandpass filter. Four identical arc-oriented slots are first symmetrically etched into the circular patch resonator to move the TM01-like mode to a lower frequency. Together with the TM21-like mode, these two modes make up the second passband of the proposed filter. A pair of radial-oriented slots is then etched into the edge of the circular patch to split a pair of TM11-like degenerate modes, which forms the first dual-mode passband. Two high-impedance transmission lines are connected to the proposed resonator at a 90° angle to properly excite the four resonant modes described above. Finally, a filter with input/output cross coupling is designed, fabricated and tested to demonstrate the dual-mode dual-band filtering performance, which exhibits a sharp out-of-band rejection skirt and good rejection between the dual passbands.

Comparing short and long-distance dispersal: modelling and field case studies

Dispersal is a factor of great importance in determining a species spatial distribution. Short distance dispersal (SDD) and long distance dispersal (LDD) strategies yield very different spatial distributions. In this paper we compare spatial spread patterns from SDD and LDD simulations, contrast them with patterns from field data, and assess the significance of biological and population traits. Simulated SDD spread using an exponential function generates a single circular patch with a well-defined invasion front showing a travelling-wave structure. The invasive spread is relatively slow as it is restricted to reproductive individuals occupying the outer zone of the circular patch. As a consequence of this dispersal dynamics, spread is slower than spread generated by LDD. In contrast, the early and fast invasion of the entire habitat mediated by power law LDD not only involves a significantly greater invasion velocity, but also an entirely different habitat occupation. As newly dispersed individuals soon reach very distant portions of the habitat as well as the vicinity of the original dispersal focus, new growing patches are generated while the main patch increases its own growth absorbing the closest patches. As a consequence of both dispersal and lower density dependence, growth of the occupied area is much faster than with SDD. SDD and LDD also differ regarding pattern generation. With SDD, fractal patterns appear only in the border of the invasion front in SDD when competitive interaction with residents is included. In contrast, LDD patterns show fractality both in the spatial arrangements of patches as well as in patch borders. Moreover, values of border fractal dimension inform on the dispersal process in relation with habitat heterogeneity. The distribution of patch size is also scale-free, showing two power laws characteristic of small and large patch sizes directly arising from the dispersal and reproductive dynamics. Ecological factors like habitat heterogeneity are relevant for dispersal, although its importance is greater for SDD, lowering the invasion velocity. Among the life history traits considered, adult mortality, the juvenile bank and mean dispersal distance are the most relevant for SDD. For LDD, habitat heterogeneity and changes in life history traits are not so relevant, causing minor changes in the values of the scale-free parameters. Our work on short and long distance dispersal shows novel theoretical differences between SDD and LDD in invasive systems (mechanisms of pattern formation, fractal and scaling properties, relevance of different life history traits and habitat variables) that correspond closely with field examples and were not analyzed, at least in this degree of detail, by the previously existing models.

Broadband dual-polarized proximity coupled circular patch antenna

This paper presents the design and results of a novel broadband dual-polarized circular patch antenna. The antenna is fed by microstrip lines through proximity coupling, and H-shaped slots are cut in the ground plane below the feed lines for enhancing the coupling between the patch and the feed lines. By using only a single circular microstrip patch, the prototype antenna yields bandwidth of 21.5% and 25.9% at the input ports 1 and 2, respectively. The isolation between two input ports is below −30 dB across the bandwidth. Good broadside radiation patterns are observed, and the cross-polar levels are below −20 dB at both E- and H-planes. Due to its simple structure, it is easy to form arrays by using this antenna as an element. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 47: 298–302, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21151

Alopecia totalis incognito

We report an 11‐year‐old boy with a strong family history of alopecia areata who initially developed alopecia areata with a single circular patch of hair loss on the scalp with exclamation mark hairs at the periphery, which evolved over time into alopecia totalis and then into a novel pattern of hair growth with fine depigmented hair, uniformly 5 mm in length. The hair has not grown any longer over a 48‐month follow‐up period. Scalp biopsies from the occipital scalp demonstrate dense peribulbar lymphocytic infiltrate and uniform miniaturized secondary vellus hairs. This previously undescribed pattern of alopecia areata is remarkable for total lack of alopecia.

Wideband dielectric resonator‐loaded suspended microstrip patch antennas

AbstractExperimental investigations of rectangular and circular suspended microstrip patch antennas with dielectric resonator loading at X‐band are reported. With loading, enhanced impedance bandwidth to about 18% is achieved in a single circular patch as compared to 13% for a single rectangular patch. In both cases, with loading, there is practically no change in the respective 3‐dB beam widths of the radiation patterns in E‐ and H‐planes. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 37: 300–302, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10900

A Useful Solution for Estimating Contact Pressure Between a Plate and Foundation

Many manufacturing situations involve a finite thickness plate or layer of material which is pressed against a much thicker foundation of the same or different material. One key example is a blank holder (plate) pressed against a die (foundation) in a sheet metal forming operation. In designing such a plate/foundation system the design objective often involves the contact stress distribution between the plate and foundation and the design variables are typically the thickness and modulus of the plate, the stiffness of the foundation and the applied pressure distribution on the noncontacting side of the plate. In general the problem relating the variables to the contact pressure distribution is three-dimensional and requires a complex finite element or boundary element solution. However, if the applied pressure distribution consists of sufficiently localized patches, which is often the case in applications, then an approximate 3D solution can be constructed by superposition. Specifically, the paper provides a convenient calculation procedure for the contact pressure due to a single circular patch of applied pressure on an infinite, isotropic, elastic layer which rests on a Winkler foundation. The procedure is validated by using known analytical solutions and the finite element method (FEM). Next a sensitivity study is presented for ascertaining the validity of the solution’s use in constructing solutions to practical problems involving multiple patches of loading. This is accomplished through a parametric study of the effects of loading radius, layer thickness, layer elastic properties, foundation stiffness and the form of the applied pressure distribution on the magnitude and extent of the contact pressure distribution. Finally, a procedure for determining an appropriate Winkler stiffness parameter for a foundation is presented. [S1087-1357(00)00603-1]

Evaluation of input impedance and radar cross section of probe-fed microstrip patch elements using an accurate feed model

Input impedance and radar cross section results for probe-fed single rectangular and circular microstrip patch elements obtained using an accurate and efficient numerical model are presented. The model uses a full-wave Green's function/Galerkin solution in which the connection of a vertical probe feed to the patch is rigorously included in the analysis by use of a special basis function called the attachment mode, which is derived from the corresponding cavity model solution. Comparisons with measured input impedance and monostatic radar cross section data demonstrate the efficacy of the theory. This model accurately predicts the performance of probe-fed patches printed on thick and/or high dielectric constant substrates and patch elements with more than one probe feed, cases where other less rigorous models fail. >