Antenna Substrate Research Articles

Low-Profile Air-Filled Antenna for Next Generation Wireless Systems

In this study, a novel design of insensitive antenna with improved radiation performance is designed and investigated. The antenna exhibits excellent performance in terms of impedance-matching, radiation and total efficiencies, even though it is designed and fabricated using high loss substrate (FR) with compact dimension. An L-shaped metal-ring resonator has been used as a main resonator of the antenna to operate at 18.5 GHz. In order to improve the antenna performance, a part of substrate with L-shaped configuration has been removed and a metal ring structure is inserted. By using this technique, we can improve the efficiency characteristic of the antenna and eliminate the effect of high-loss FR-4 substrate. The center frequency of the designed antenna can be controlled by adjusting the values of the antenna parameters. Since the main substrate of the resonator is the air, the antenna is insensitive for different types of antenna substrates. It has the return loss characteristic less than −10 dB in the frequency range of 17.5–19.5 GHz (more than 10% fractional bandwidth). The antenna has a very compact size with good radiation behavior and could be used in phased array antennas for next generation systems.

Performance of a Wideband Cadmium Ferrite Microstrip Patch Antenna in the X-Band Region

Magnesium-substituted cadmium ferrites with the chemical composition Mg x Cd1−x Fe2O4 (x = 0, 0.4 and 0.8) were prepared by an oxalate co-precipitation method under microwave sintering technique. The structural properties of ferrites were studied by x-ray diffraction, Fourier transform infrared spectroscopy and field emission scanning electron microscope techniques. The scattering parameters such as reflection coefficient (S 11) and transmission coefficient (S 21) at microwave frequencies of palletized ferrites were measured by using a vector network analyzer. The software module 85071E followed by scattering parameters was used to determine the electromagnetic properties of the ferrites. The values determined for electromagnetic parameters such as the real part of permittivity (e′), permeability (μ′), dielectric loss tangent (tanδ e) and magnetic loss tangent (tanδ m) of synthesized ferrites were used to design rectangular microstrip patch antennas. The performance of magnesium-substituted Cd ferrites as substrate for microstrip patch antennas was investigated. The antenna parameters such as return loss, bandwidth, voltage standing wave ratio, Smith chart and radiation pattern were studied. It is found that the Cd ferrite has applicability as a substrate for wideband antennas in the X-band region.

RF Parameters Characterization of a Flexible Cu-PDMS-Cu Patch Antenna

This paper presents a newly developed flexible Polydimethylsiloxane (PDMS)-Copper (CU) patch antenna. The circular-shaped antenna consists of a 21.28mm radial size Cu patch embedded on a PDMS square substrate. PDMS has a low loss tangent of 0.004 and a relative permittivity of 2.74 that will enhance the RF parameters of the flexible antenna. There are three layers of material used to build the antenna. The first and the third layers are made from Cu tape and function as the ground and patch respectively. Meanwhile, the sandwiched layer is the PDMS substrate. However, several limitations of the antenna were observed, including low adhesiveness between layers, which made it impossible to perform metal and dielectric depositions. Thus, a thin layer of PDMS has been built on top of a patch layer to increase the adhesive strength between the copper patch and the PDMS substrate. The paper also discussed the return loss of the antenna with and without sandwich in planar, bending in x-axis and y-axis. The measurements using a vector network analyzer (VNA) demonstrated that the sandwich antenna can resonate at 2.33GHz with a low return loss of 42dB. The work is a proof of the principle that the PDMS substrate can be proposed as a good substrate for antenna in conformal applications.

Loaded dipole antennas with new CRLH cell configuration

In this paper, two different triple band dipole antennas loaded by new modified composite right left handed cell are presented. The modified cell can introduce large electrical length in small size. Thus, the two antennas are designed with smaller operating frequency or reduced physical length compared to a single frequency reference dipole. The designed antennas can serve different wireless services for GPS (1.27GHz and 1.55GHz), UMTS (1.85GHz), and WiFi (2.4GHz) in triple band functionalities. The lower operating frequency antenna size is (70×70 mm2) whereas the reduced physical length antenna size is (60×70mm2). At mid band frequencies the reduced frequency antenna length is (0.29 λ0, 0.37 λ0, and 0.52 λ0), whereas that of the reduced physical length is (0.28 λ0, 0.41 λ0, and 0.56 λ0), at triple band mid frequency, respectively. Compared to a typical dipole antenna, the designed loaded dipoles can achieve a length reduction that can reach up to 50%. Moreover, the antenna has good gain at the triple bands (−1.2dB, 1.9dB and 3.5dB for reduced operating frequency antenna and −3.1dB, 1.2dB and 3.4dB for the reduced length antenna. The two antennas have good radiation efficiency that can reach up to 84% on a low cost antenna substrate. The mathematical analysis, full wave simulation and experimental measurements of the reported antennas are introduced.

Compact Dual Band-Notched Monopole Antenna with Modified Radiating Patch for UWB Wireless Applications

Ultra-wideband (UWB) planar antennas with single or multiple notched frequency bands properties have recently been considered for various communications between wireless devices. In this study, a low profile microstrip monopole antenna with double band-filtering function is designed and investigated. FR-4 dielectric with properties of e = 4.4 and δ = 0.02 has been employed as the antenna substrate. The configuration of the proposed design is composed of a modified fork-shaped radiating patch with inverted Ω-shaped slot and a pair of coupled Γ-shaped parasitic structures, a feed-line and a ground plane. The proposed dual band-notched UWB antenna provides good impedance bandwidth characteristic from 2.89 to 12.43 GHz for VSWR <2 with two notched bands which cover all the 5.2/5.8 GHz of WLAN, 3.5/5.5 GHz of WiMAX and 4-GHz of C bands ranges. The antenna provides good radiation behavior with sufficient gain levels over its operation frequency band.

Resonant characteristics of aperture type FSS and its application in directivity improvement of microstrip antenna

In this paper, we propose an aperture type frequency selective surface (FSS) by employing an array of 12×12 unit cell elements and its resonant characteristics is analyzed. A resonant cavity antenna is then formed by the ground plane substrate and the FSS superstrate. The high reflective behavior of the proposed FSS at an offset of the resonance is then utilized for improving the performance of this cavity antenna. The impedance bandwidth and directivity are improved up to 0.66GHz and 8.95dBi, simultaneously at an optimum gap of 17.6mm between the antenna substrate and FSS superstrate. For validation purpose, prototypes of both patch antenna and FSS, are fabricated and characterized. A fairly good agreement is achieved between the measured and simulated results.

Analysis Reconfigurable Frequency Textile Antenna in Bending Condition

In this paper, the analysis of reconfigurable frequency textile antenna in bending conditions is presented. The antenna consists of a truncated rectangular patch and slotted ground plane made by ShieldIt Super. Felt fabric is used as an antenna substrate. The proposed antenna is capable to reconfigure at seven different states frequencies by using three PIN diodes. The Circular Polarization (CP) is achieved at the GPS operating frequency. Meanwhile, the proposed antenna operates as a Linear Polarization (LP) at high operating frequencies. The performances of antenna in bending conditions is analyze since the textile antenna usually attached on the body will easily bend due to the human body structures. Details of the simulation results for antenna in bending condition are discussed.

Low dielectric permittivity and low loss of low temperature co-fired Li2ZnxMg0.98−xCo0.02SiO4 ceramics with LiF–Bi2O3 additives

In present study, low temperature co-fired Li2ZnxMg0.98−xCo0.02SiO4 ceramics with LiF–Bi2O3 additives were prepared by solid state reaction method. The LiF and Bi2O3 additives were not only reducing the sintering temperature of Li2ZnxMg1 − xCo0.02SiO4 ceramics, but also enhancing the dielectric properties. The effects of LiF–Bi2O3 on structure and dielectric properties were investigated. Under the additive action, all XRD patterns showed the single phase and the grain size increased gradually. Additional, the ratio of Zn2+ and Mg2+ ions affected the structure and properties of Li2ZnxMg0.98−xCo0.02SiO4 ceramics. When x = 0.6, the real part of dielectric permittivity was about 6.12 at 1 MHz–1.5 GHz, while the dielectric loss was about 1.2 × 10−3, which was fairly potential application for antenna substrate.

Advanced microwave effective medium theory for two-component nonmagnetic metamaterials: fundamentals and antenna substrate application

A modification of effective medium theory for two-component nonmagnetic metal---dielectric metamaterials is developed for use in the microwave frequency range. The metamaterial is represented as an unbounded isotropic dielectric host material with periodically embedded nonmagnetic metallic inclusions of cylindrical or spherical shape. The effective electromagnetic response of the metamaterial is represented by the tensor of the effective relative permittivity and tensor of the effective relative permeability. The losses of the metamaterial are also evaluated in this study. A physical interpretation for the nature of the effective properties of such metamaterials is given. Analytical models of the proposed effective medium theory are benchmarked against numerical simulations using commercial electromagnetic software. Two compact microwave rectangular dual-band patch antennas on such metamaterial substrates are designed in this study.

Performance and design of spear shaped antenna for UWB band applications

This paper presents a novel design of a spear shaped antenna for wireless communications. Presently many research groups are working on wireless communication technologies and proposed various types of antenna designs. This proposed antenna fulfills the requirement of low cost, less weight, small size for wireless devices. The design and simulation of proposed CPW fed antenna are carried out with RT Duroid substrate and dimension of antenna substrate is 14mm×18mm. The operating frequency of the proposed antenna is 3.1–10.8GHz. High Frequency Structure Simulator software HFSS's optometric is used for the proposed antenna for more accuracy and results are optimized. The simple configuration and low profile attributes of the proposed antenna made it easy for fabrication and suitable for the application in the UWB band applications.

Breast cancer detection using K-nearest neighbors data mining method obtained from the bow-tie antenna dataset

Breast cancer, has been a significant cancer type for women on the society. Early diagnosis and timely medical treatment are important key factors spreading to the other tissues and permitting long-time survival of patients. Since the existing methods have several serious shortfalls, microwave imaging method for the diagnosis of early stage tumors has been interested by different scientific research groups in terms of moderating endogenous the electrical property difference between healthy tissue and malignancies. In this article, both an ultra-wideband bow-tie antenna with enhanced bandwidth and a 3D breast model which has different electrical properties which are permittivity and conductivity is created in simulation tool to solve electromagnetic field values. Return loss, VSWR, and radiation pattern characteristics, which are significant antenna parameters, are simulated and obtained whether the antenna possess an efficient characteristic or not. Electric field values over the breast tissue in which there is a tumor or not tumor are evaluated. In this article, above-mentioned values of frequency bandwidth, dielectric constant of antenna's substrate, electric field, and tumor information were consisted in their dataset. This dataset obtained from the Bow-Tie Antenna was used to detect the breast cancer with one of the data mining method, which is K-Nearest Neighbor Algorithm.

An efficient small size electromagnetic energy harvesting sensor for low‐DC‐power applications

An efficient small size electromagnetic energy harvesting sensor for low-DC-power applications is proposed. The sensor consists of two main parts: a dual polarisation square patch antenna used to collect the RF energy at a central frequency of 2.45 GHz, and two voltage doublers rectifier circuit for the RF-to-DC conversion. The overall size of the design is 50 × 50 × 6.2 mm3. Firstly, the antenna is designed using high-frequency structure simulator software; followed by the design of the rectifier circuit in advanced design system. After simulations, a sensor prototype is fabricated using F4B as the antenna substrate. Measurements show that the sensor achieves a comparatively high maximum measured efficiency of 41% for a power level of −10 dBm. The sensor has a simple structure, it is compact sized, light weight, and presents a high RF-to-DC conversion efficiency for low-RF-power levels which can be used to charge different low-DC-power devices.

Low-loss NiZnCo ferrite processed at low sintering temperature with matching permeability and permittivity for miniaturization of VHF-UHF antennas

Spinel ferrites of a nominal composition of Ni0.5Zn0.3Co0.2Fe2O4 (NiZnCo) with various B2O3–Bi2O3–SiO2–ZnO (BBSZ) glass additions were successfully synthesized at a relatively low temperature of 930 °C for their potential applications as magneto-dielectric antenna substrate materials. Measurements of magnetic and dielectric properties show that, with an increasing content of BBSZ from 0 to 2 wt. %, the permeability μ′ at low frequencies was increased from ∼4.7 to ∼8.9, whereas the permittivity ε′ was improved from ∼5.9 to ∼12.5. These tunable permeability and permittivity were proved to be closely related to the grain size and density, based on the magnetic circuit model and effective medium theory. Importantly, the sample with 0.5 wt. % addition demonstrated the optimal magneto-dielectric performance with nearly equivalent values of μ′ and ε′, which yields a large miniaturization factor of ∼6.5 and the normalized impedance of ∼1 over the frequency range of 10 MHz–1 GHz. Moreover, this sample exhibits low loss characteristics over a wide frequency range, where the dielectric loss tan δε is in the order of 10−3 and the magnetic loss tan δμ is less than 0.15. These properties make the ferrite material a promising candidate for miniaturized antennas with good impedance matched to free space and open a great potential for low-temperature co-fired ceramic applications toward the practical fabrication and high integration of the antennas.

Electrical properties of niobium pentoxide (NB2O5) for application in microstrip antenna substrate

ABSTRACTThis article presents a parameters investigation of microstrip antenna substrate produced by niobium pentoxide (Nb2O5) powder metallurgy. Theoretical studies and experimental measurements of the substrate electrical properties were performed. The niobium pentoxide compaction pressure and the sintering temperature were studied in order to determine a relationship between pressure, temperature and electrical properties, aiming to apply to a microstrip patch antenna. © 2017 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:641–645, 2017

Exponential Antipodal Vivaldi Antenna With Exponential Dielectric Lens

The expansion of wireless technologies poses various requirements such as stable radiation characteristics in a wide frequency range. This letter presents an exponential antipodal Vivaldi antenna with a dielectric lens replacing part of the substrate in antenna aperture, with dimensions of 76 × 130 mm2. The shape of the lens also follows exponential structure in its inner (where lens meets the antenna substrate) and outer edges. Using a dielectric with higher constant in the proposed antenna provides 1 dB improvement in antenna gain and 24% of 3-dB beamwidth reduction.

Embedded 6-GHz 3-D Printed Half-Wave Dipole Antenna

In this letter, a three-dimensional packaged half-wave dipole antenna is presented. The design includes a grounded coplanar waveguide (GCPW) balun that is printed on an inclined surface and used to connect the 50-Ω feedline on the lower layer to the dipole on the top layer. For matching purposes, a GCPW quarter-wave transformer is incorporated between the 50-Ω feedline and the balun. The 6-GHz half-wave dipole is approximately λ/4 above the ground plane. Fabrication is done using the direct digital manufacturing technique with an acrylonitrile butadiene styrene substrate (relative permittivity of 2.7 and a loss tangent of 0.008) and Dupont CB028 silver paste. The simulated and measured gains are 4.88 and 4.7 dBi, respectively. Antenna substrate surface roughness is analyzed to explain discrepancies between simulation and measurement results.

Miniaturized UWB Antipodal Vivaldi Antenna and Its Application for Detection of Void Inside Concrete Specimens

A miniaturized antipodal Vivaldi antenna to operate from 1 to 30 GHz is designed for nondestructive testing and evaluation of construction materials, such as concrete, polymers, and dielectric composites. A step-by-step procedure has been employed to design and optimize performance of the proposed antenna. First, a conventional antipodal Vivaldi antenna (CAVA) is designed as a reference. Second, the CAVA is shortened to have a small size of the CAVA. Third, to extend the low end of frequency band, the inner edges of the top and bottom radiators of the shortened CAVA have been bent. To enhance gain at lower frequencies, regular slit edge technique is employed. Finally, a half elliptical-shaped dielectric lens as an extension of the antenna substrate is added to the antenna to feature high gain and front-to-back ratio. A prototype of the antenna is employed as a part of the microwave imaging system to detect voids inside concrete specimen. High-range resolution images of voids are achieved by applying synthetic aperture radar algorithm.

Greatly enhanced magneto-dielectric performance of the Ni0.5Zn0.5Fe2O4/polyvinylidene fluoride composites with annealed ferrite powders for antenna applications

Abstract

Performance analysis of cobalt metal with fluoropolymer matrix as a substrate for patch antenna

ABSTRACTSince many decades material plays major role in all fields. In recent years, materials are more useful in specific field of science and engineering. This paper deals with micro-strip patch antenna designed using FR-4 and magneto dielectric substrate. To compare these results, CSTMWS Suite (Computer Simulation Technology Micro-Wave Studio) software is used. The results show that different substrate produce different gain and directivity based on their properties. Here, two different materials namely FR-4, Cobalt metal with fluoropolymer matrix are used as a substrate for same structure.

An Artificially Anisotropic Antenna Substrate for the Generation of Circular Polarization

The purpose of this communication is to present the design of an artificially anisotropic antenna substrate (AAAS) for the generation of circular polarization (CP) for a linearly polarized antenna. The AAAS can be manufactured by assembling thin sheets with certain relative permittivities for the host or environment $\varepsilon _{e}$ and inclusion $\varepsilon _{i}$ materials as a stack. Using two different stacking materials enables the generation of different effective permittivities $\varepsilon _{{{x{'}}}}$ and $\varepsilon _{{{y{'}}}}$ for the wave components propagating in-between an antenna and a ground. The idea is to modify the antenna polarization by exploiting reflections from a ground in a way that CP operation is obtained. By properly designing the AAAS, the radiator shape can be maintained simple. The operation of AAAS is demonstrated for substrates made of homogeneous anisotropic and thin sheets. It is shown that by using sufficient high inclusion permittivity (e.g., $\varepsilon _{i} = 15$ ), the AAAS is observed to even show axial ratio <2 dB with over 25 dBi higher right-hand CP gain than left-hand CP in the main beam of the antenna. A prototype with available low-lossy materials is manufactured and successful correlation with theory and simulation results is observed.