Antenna Substrate Research Articles

Design of planar monopole antenna in velvet shape having two gap sleeves

In this study, a wideband antenna was proposed by adding two strip sleeves with gaps according to a velvet shape in a planar monopole shape basically having the velvet structure. By adding two gap sleeves, additional resonance could be induced, thereby inducing impendence matching effectively. Through the antenna property analysis, it was confirmed that changes in the feed gap, sleeve length, and sleeve gap are important parameters of impedance matching. The total size of antenna substrate was 40 mm × 40 mm2, and FR4 dielectric substrate with 1 mm thickness was used. As a measurement result, the bandwidth of 10 dB was confirmed to be 12.09 GHz in the 2.91–15 GHz bands. In all frequencies, results similar to the radiation pattern of dipole antenna were shown. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:21–24, 2016

Metal semishell-substrate coupled structures with enlargened near-field enhancement area

Metal antennas-substrate coupled structures have unique features of strong nanoscale light confinement and field enhancement at the gap, which make them attractive and promising in a variety of applications such as sensing, lasing, and solar cell. Here, we built a coupled system consisting of a gold spherical semishell antenna and gold substrate. Through numerical simulation, it is found that due to the unique geometric shape of the antenna, the near-field enhancement area of the localized resonance is enlarged dramatically in the designed plasmonic structure, which is beneficial to increasing the active region, allowing more molecular adsorbed and also replaced easily. Moreover, the far-field extinction spectra of the localized dipole mode in the designed structure has higher quality factor and is more robust to the gap separation than its solid counterpart, which may relax the fabrication tolerances.

Metamaterial-Embedded Low SAR PIFA for Cellular Phone.

A metamaterial-embedded planar inverted-F antenna (PIFA) is proposed in this study for cellular phone applications. A dual-band PIFA is designed to operate both GSM 900 MHz and DCS 1800 MHz. The ground plane of a conventional PIFA is modified using a planar one-dimensional metamaterial array. The investigation is performed using the Finite Integration Technique (FIT) of CST Microwave Studio. The performance of the developed antenna was measured in an anechoic chamber. The specific absorption rate (SAR) values are calculated considering two different holding positions: cheek and tilt. The SAR values are measured using COMOSAR measurement system. Good agreement is observed between the simulated and measured data. The results indicate that the proposed metamaterial-embedded antenna produces significantly lower SAR in the human head compared to the conventional PIFA. Moreover, the modified antenna substrate leads to slight improvement of the antenna performances.

Cobalt Nanoparticle Inks for Printed High Frequency Applications on Polycarbonate

In this work the high frequency properties of low curing temperature cobalt nanoparticle inks printed on polycarbonate substrates were investigated. The inks consisted of 30–70 vol.% metallic cobalt nanoparticles and poly (methylene methacrylate) polymer, having excellent adhesion on polycarbonate and a curing temperature of 110°C. The influence of binder material content on the electromagnetic properties of the ink was investigated using the shorted microstrip transmission-line perturbation method. Changes in mechanical properties were evaluated with adhesion tests using the pull-out strength test and the ASTM D 3359-B cross-hatch tape peel test. The microstructure of the printed patterns was investigated with field emission scanning electron microscopy (FESEM). The inks remained mechanically durable with metal contents up to 60 vol.%, achieving pull-off strength of up to 5.2 MPa and the highest marks in adhesion of the tape peel test. The inks obtained a relative permeability of 1.5–3 in the 45 MHz–10 GHz band with a magnetic loss tangent of 0.01–0.06. The developed inks can be utilized in various printed electronics applications such as antenna miniaturization, antenna substrates and magnetic sensors or sensing.

Microstrip patch antenna project with split ring resonator periodically arrayed on the substrate

ABSTRACTThis article presents an investigation about the parameters of rectangular microstrip patch antennas with resonators on the antenna's substrate, through a experimental collection, it has been observed a simulation analysis and its verification by measured data. This investigation refers to two arrayed sets on the substrate, the first one with 16 resonators and the second one with 36. The substrate composition of the antenna have been based on the use of split ring resonators, periodically organized on arrays and confined on the substrate. By applying this proposal, it has been made an evaluation of return loss behavior related to the operation frequency, bandwidth, gain, and feature impedance, in which intended to compare the obtained values to each spacial disposition of the resonator elements. The result analysis demonstrated acceptable agreement between simulated and measured values. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:2715–2720, 2015

Reconfigurable Frequency Textile Antenna with Circular Polarization Using Slotted Technique

This paper presents a reconfigurable frequency microstrip patch textile antenna using slotted technique. The switchable frequency is achieved by implementing three PIN diode switches at the slotted ground of the antenna. It is discovered that the switching element is capable to configure the frequency at six different states of operating frequencies between 1.575 GHz until 2.45 GHz. With certain switches configuration, the antenna is proficient to produce a dual-band frequency of band 1; 1.575 GHz and 2.45 GHz and band 2; 1.588 GHz and 2.36 GHz. Besides, the antenna has successfully perform an axial ratio of less than <3 dB at the GPS operating frequency of 1.575 GHz. A shieldit super is used for the antenna radiator and felt fabric as the antenna substrate. The design and simulated result shows that the presented antenna is potential to be implemented in GPS and Wi-Fi applications.

Flexible three‐dimensional printed antenna substrates

Flexible heterogeneous substrates have been constructed, using three-dimensional printing in a single process, by introducing air-filled slots. These substrates have been used to substantially reduce the substrate losses for a flexible microstrip patch antenna causing an increase in its radiation efficiency. By combining transverse magnetic (TM)10 and TM01 modes the bandwidth of this antenna has also been increased.

A circularly polarized planar antenna on flexible substrate for ultra-wideband high-band applications

This paper presents the design of a circularly polarized slot antenna on a flexible substrate for ultra-wideband (UWB) high-band applications, as well as the behavior of the antenna near a human body. We used two slots that were crossed perpendicularly to obtain a circularly polarized wave. We realized wideband impedance matching to optimize the lengths and widths of the antenna slots and substrate. The impedance bandwidth of proposed antenna is 5.60GHz from 7.11 to 12.71GHz, and the antenna size is 16mm×16.3mm×0.254mm.

Characterisation of antenna substrate properties using surrogate‐based optimisation

In the current study, the authors present a technique to characterise the permittivity and loss tangent of an antenna substrate. In this method, an error function is formulated with measured data and a set of simulation data on the antenna's impedance and bandwidth. Subsequently, a surrogate-based optimisation code is used to intelligently search for the substrate parameters that minimise the error function. The validity of the method is demonstrated by experiments on wearable patch antennas with felt substrates. The results show that the method is effective in retrieving the permittivity and loss tangent of the antenna substrate using the antenna itself as the test fixture. Thus, there is no need to prepare additional resonators or transmission-line fixtures as in conventional substrate characterisation methods.

A theoretical and numerical approach for selecting miniaturized antenna topologies on magneto-dielectric substrates

An increasing interest is arising in developing miniaturized antennas in the microwave range. However, even when the adopted antennas dimensions are small compared with the wavelength, radiation performances have to be preserved to keep the system-operating conditions. For this purpose, magneto-dielectric materials are currently exploited as promising substrates, which allows us to reduce antenna dimensions by exploiting both relative permittivity and permeability. In this paper, we address generic antennas in resonant conditions and we develop a general theoretical approach, not based on simplified equivalent models, to establish topologies most suitable for exploiting high permeability and/or high-permittivity substrates, for miniaturization purposes. A novel definition of the region pertaining to the antenna near-field and of the associated field strength is proposed. It is then showed that radiation efficiency and bandwidth can be preserved only by a selected combinations of antenna topologies and substrate characteristics. Indeed, by the proposed independent approach, we confirm that non-dispersive magneto-dielectric materials with relative permeability greater than unit, can be efficiently adopted only by antennas that are mainly represented by equivalent magnetic sources. Conversely, if equivalent electric sources are involved, the antenna performances are significantly degraded. The theoretical results are validated by full-wave numerical simulations of reference topologies.

Large-Scale Arrays of Bowtie Nanoaperture Antennas for Nanoscale Dynamics in Living Cell Membranes.

We present a novel blurring-free stencil lithography patterning technique for high-throughput fabrication of large-scale arrays of nanoaperture optical antennas. The approach relies on dry etching through nanostencils to achieve reproducible and uniform control of nanoantenna geometries at the nanoscale, over millimeter-sizes in a thin aluminum film. We demonstrate the fabrication of over 400 000 bowtie nanoaperture (BNA) antennas on biocompatible substrates, having gap sizes ranging from (80 ± 5) nm down to (20 ± 10) nm. To validate their applicability on live cell research, we used the antenna substrates as hotspots of localized illumination to excite fluorescently labeled lipids on living cell membranes. The high signal-to-background afforded by the BNA arrays allowed the recording of single fluorescent bursts corresponding to the passage of freely diffusing individual lipids through hotspot excitation regions as small as 20 nm. Statistical analysis of burst length and intensity together with simulations demonstrate that the measured signals arise from the ultraconfined excitation region of the antennas. Because these inexpensive antenna arrays are fully biocompatible and amenable to their integration in most fluorescence microscopes, we foresee a large number of applications including the investigation of the plasma membrane of living cells with nanoscale resolution at endogenous expression levels.

Bandwidth and gain enhancement of RMPA using ‘c’ shaped metamaterial at THz

This paper elucidates antenna parameter optimization using C shaped metamaterial embedded in antenna substrate at high frequency (THz). Ansoft HFSS version 13 has been used to design and analyse the RMPA (Rectangular Microstrip Patch Antenna ) with design frequency 2.75 THz and operating range of 2.15 THz to 3.35 THz having FR4 (εr = 4.4) as substrate material . Nicolson Ross Wier (NRW) method has been used to retrieve the material parameters from transmission and reflection coefficient. . Results were compared with MATLAB programming based on CAD formulas using equivalent circuit analysis of patch antenna. Finally, antenna parameters such as gain, bandwidth, and radiation pattern are investigated and presented in tables and response-graphs. The unique shape proposed in this paper, gives remarkable enhancement in bandwidth and antenna gain.

MEMS patch antenna array with broadband and high-gain on double-layer silicon wafers

A MEMS patch antenna which can be integrated with RF module easily was designed to improve the bandwidth and gain of the traditional microstrip antenna. The equivalent dielectric constant of substrate of the microstrip antenna was optimized to greatly increase the bandwidth of the antenna by a high resistivity silicon being bonded to a low resistivity silicon to form a double-layer silicon substrate under the MEMS technology. Defected ground structure was also used on ground plane in order to restrain the harmonic radiation of antenna. Based on the above aspects, a 22 antenna array was designed with a center frequency of 10 GHz. The simulation results show that the antenna array has an impendence bandwidth of 15.9% and a gain of 10.9 dB, significantly better than traditional antennas and meets the anti-interference requirements of antennas in the fuze.

Effects of Mg2.05SiO4.05 addition on phase structure and microwave properties of MgTiO3–CaTiO3 ceramic system

The (1−x) MgTiO3−xMg2.05SiO4.05–0.06CaTiO3 ceramic system composite dielectric ceramics with different amounts of Mg2.05SiO4.05 addition were prepared by solid state reaction method. The results indicated that exceeding Mg in Mg2.05SiO4.05 not only hold back the formation of MgSiO3 but also inhibits the formation of second phase MgTi2O5. A new microwave dielectric material, 0.8MgTiO3–0.2Mg2.05SiO4.05–0.06CaTiO3 ceramics sintered at 1380°C for 4h had optimal dielectric properties (εr=15.4, Q×f=72,705GHz and τf=−1.45ppm/°C) which satisfied microwave applications in resonators, filters and antenna substrates.

Linear Low Density Polyethylene (LLDPE) as Flexible Substrate for Wrist and Arm Antennas in C-Band

This paper focuses on the development and study of linear low density polyethylene as a flexible substrate for conformal antennas for body-worn applications. Thermal stability, tensile strength and elongation at break of the substrate were studied. The permittivity of the substrate was 2.2 and tan δ was found to be 0.0003 at 6 GHz. Since the antenna is being developed for wrist and arm wearing in C-band, the performance of the antenna, such as the S11 parameter and radiation pattern, were studied with different bending axes and with bending curvature approximating that of the arm and wrist. The performance of a 6 GHz rectangular patch antenna with bending was found to be consistent with the flat profile antenna at the same frequency. A maximum shift in the resonant frequency of ∼20 MHz was observed. The −10 dB bandwidth and directivity of the antenna did not change much with bending. The maximum bending radius in the present study is 10 mm, and S11 was found to be −17.53 dB at 5.94 GHz and −14.02 dB at 6.06 GHz for a bending axis parallel to the radiating and non-radiating edge, respectively.

Waveguide fed circular microstrip patch antenna for Ku band applications

This article presents the design and development of a waveguide fed microstrip patch antenna for Ku band applications. A circular patch is fed using a conventional WR-51 rectangular waveguide ended with a feeding slot capacitively coupled to the radiating patch. The design is optimized using the electromagnetic software CST Microwave Studio. The antenna is fabricated and the measured results are compared with simulations. The achieved bandwidth of the manufactured antenna is approximately 16.2–18.4 GHz, and a maximum gain of 5.7 dBi. The comparison of measured and simulated results shows good agreement except in the prediction of the surface wave effects propagated in the antenna substrate. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:585–589, 2015

High performance of coaxial feed UWB antenna with parasitic element for microwave imaging

A high performance of coaxial feed ultrawide band (UWB) array antenna with parasitic element is proposed in this article. The 4 × 1 array antenna consists of four identical copper circular patches are appropriately connected using quarter-wavelength transformer transmission line. The array elements and its feed network are properly optimized to have a high-gain performance over wide range bandwidth frequencies. Introduction of semicomplementary copper parasitic element with copper partial ground technique are applied in this proposed antenna to obtain optimum large bandwidth. Taconic associated with 2.2 dielectric constant and thickness of 1.6 mm is used as the antenna substrate. Less complicated fabrication methods is possible due to the feeding network placement is on the same level with the antenna patch elements. The performance of the designed antenna evaluated in term of return loss, bandwidth, radiation pattern, directivity, and gain. The proposed antenna recorded reflection coefficient less than −10 dB started from 2.5 to 12.6 GHz which fulfilling the requirement of UWB. Dimensions of 80 × 45 mm2 and maximum gain of 12.12 dB made it as small and high gain UWB antenna. The antenna exhibits a stable gain from 3.4 to 12.12 dB over the operated frequencies and has 83% of usable fractional bandwidth. The proposed antenna performance finds it very suitable to be applied in human brain microwave imaging. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:649–653, 2015

Planar Endfire Circularly Polarized Antenna Using Combined Magnetic Dipoles

A novel planar circularly polarized antenna with endfire radiation beam in parallel with the antenna substrate’s plane is proposed. The operation principle of the antenna is analyzed and design guidelines are laid down. Then, an optimized loop-aperture combined antenna is designed and demonstrated to exhibit an endfire beam in parallel with its plane within 5.74-5.88 GHz for $\vert{{\rm S}_{11}}\vert$ lower than $-10~\hbox{dB}$ and axial ratio smaller than 3 dB. The proposed antenna can be used as a low-profile, cost-effective, hand-held reader antenna for radio frequency identification systems .

Novel Microstrip Antenna Design Upon Transformation Medium

In this letter, the substrate of a microstrip antenna is chosen as the transformation medium. Using complex transformation optics, a standing-wave current distribution along the circumference of a circular patch is transformed into a uniform traveling current distribution instead, thus generating perfectly circularly polarized waves. This letter provides a novel way of designing the microstrip antenna whereby the traditional substrate is replaced by the transformation medium whose parameters can be readily derived from the theory of transformation optics. Furthermore, introducing complex transformation optics into antenna design is a new attempt. In terms of its flexibility of controlling the amplitude distribution of electromagnetic fields, it offers extra freedom of manipulating the radiation pattern of an antenna.

Biological effect of SAR on the human head due to variation of dielectric properties at 1800 and 2450 MHz with different antenna substrate materials

AbstractThe aim of this study was to consider a possible discrepancy in electromagnetic (EM) absorption in the human head. The finite-difference time-domain (FDTD) method with the lossy Drude model was adopted in this study. Here, the permittivity and conductivity of all head tissues were increased from 10% to 20% except when not using the same exposure conditions. Recognizable mobile phone frequencies of 1800 and 2450 MHz were studied in this simulation. The increase of up to 20% in conductivity and permittivity and varied substrate material always caused an EM absorption variation of 32.59% for specific absorption rate (SAR) 1 g and 35.25% for SAR 10 g at 1800 MHz, and variation of 20.37% for SAR 1 g and 17.99% for SAR 10 g at 2450 MHz, respectively.