Antenna Substrate Research Articles

Transmission and Reflection Properties of Iron Pyrite-Epoxy Resin Composite for Electromagnetic Applications

This study examines the electromagnetic properties of a composite material composed of iron pyrite (FeS2) and epoxy resin, mixed in a 3:2 weight ratio to create a 10 cm3 cube. The research analyzes transmission and reflection coefficients and band gap parameters to determine its viability as an antenna substrate for electromagnetic wave applications. The composite displays a tunable band gap of 1.3 eV, enabling selective absorption and emission of electromagnetic radiation. The transmission coefficient achieved 90% throughout a frequency range of 1 GHz to 15 GHz, whilst the reflection coefficient was measured at 10%, significantly reducing reflecting losses. The epoxy resin binder was essential for preserving structural integrity and augmenting the dielectric characteristics of the composite, thereby raising transmission efficiency. UV-Vis spectroscopy showed an absorption value of 0.875% at the band gap, indicating efficient interaction with UV energy. The S21 transmission coefficient ranged from −10 dB to −80 dB, with a maximum of −40 dB at 6 GHz, indicating strong energy transfer capability for antenna applications. The S21 values exhibited negligible signal attenuation between 2 GHz and 7 GHz, indicating the material’s exceptional suitability for antenna substrates necessitating dependable transmission. The S11 reflection coefficient varied from −5 dB to −55 dB, with substantial decreases between 4 GHz and 14 GHz, when reflection decreased to −45 dB, signifying little signal reflection at essential frequencies. The results underscore the composite’s appropriateness for applications requiring high transmission efficiency, little reflection, and effective engagement with electromagnetic waves, especially as an antenna substrate. Measurements were performed using a vector network analyzer (VNA) to obtain the S11 and S21 characteristics, underscoring the material’s potential in sophisticated electromagnetic applications.

Absorption processes of the first and second order in GaAs in the THz-IR range

Absorption of THz radiation in gallium arsenide (GaAs) substrates of photoconductive antennas determines the generation and detection efficiency, as well as the dynamic and frequency ranges, of THz spectrometers. Based on the THz and IR experimental data and their calculations using classical dispersion models, absorption processes in the THz–IR regions were analyzed, and broadband data on the temperature evolution of the optical parameters of GaAs substrates were obtained. The contribution of anharmonicity effects in the formation of the dielectric response function of GaAs in the THz range is demonstrated.

A Dual‐Polarized Wide‐Angle Scanning Linear Phased Array Antenna With Simple Decoupling Structure

ABSTRACTA dual‐polarization linear phased array with a simple decoupling structure is designed for wide scanning in this letter. The suggested antenna is made up of two printed dipole antennas that are orthogonally arranged and have a high cross‐polarized isolation. Metal sheets cladding on antenna substrates serve as a decoupling structure, with an array element spacing of 0.48 . A linear phased array of seven elements is fabricated and measured to ensure that the planned array is feasible. The simulated and measured results demonstrate that the phased array can scan its main beam up to ±75° in dual‐polarized excitations at 5.6–6.4 GHz. The co‐polarized mutual coupling is below −28 dB, and the active reflection coefficient of the element is less than −15 dB.

High-Gain Multi-Band Koch Fractal FSS Antenna for Sub-6 GHz Applications

This study introduces a novel antenna based on the binary operation of a modified circular patch in conjunction with the Koch fractal. The antenna is intended for applications in the sub-6 GHz band, partial C-band, and X-band. The low-cost antenna is fabricated on a 1.6-mm-thick FR-4 substrate. A frequency-selective surface (FSS) is used to overcome the decreased values of the gain and bandwidth due to the fractal operations. The introduced split ring resonator (SRR) and the antenna substrate dimension reduction reduce the bandwidth and antenna gain. The air gap between the FSS and the antenna not only enhances the antenna gain but also controls the frequency tuning at the design frequency. The antenna size is miniaturized to 36.67%. A monopole antenna ground loaded with an SRR results in improved closest tuning (3.44 GHz) near the design frequency. The antenna achieves a peak gain of 9.37 dBi in this band. The FSS-based antenna results in a 4.65 dBi improvement in the gain value with the FSS. The measured and simulated plots exhibit an excellent match with each other in all three frequency bands at 2.96–4.72 GHz. These bands cover Wi-MAX (3.5 GHz), sub-6 GHz n77 (3300–3800 MHz), n78 (3300–4200 MHz), and approximately n79 (4400–4990 MHz), in addition to C-band applications.

Flexible low dielectric permittivity paper as a disposable substrate for centimeter wave patch antennas

Flexible low dielectric permittivity paper as a disposable substrate for centimeter wave patch antennas

Finding the best frequency dependent performance of 3d transition metals (Co, Ni, and Mn) substituted nano magnetite for miniaturizing device applications

Ferrite samples with enhanced magneto-dielectric properties are more essential in electromagnetic applications. Therefore, a parent composition of Fe3O4 has been modified by substituting 3d transition metal elements (Co, Ni, Mn) at a single Fe atom using the co-precipitation synthesis method. The structural properties of the synthesized Fe3O4, NiFe2O4, CoFe2O4, and MnFe2O4 samples have been evaluated from the X-ray diffraction patterns. The surface morphology and microstructures of the studied samples were studied by field emission scanning electron microscopy and the average grain size of all the studied samples varied from 60.11 to 106.03 nm. The magneto-dielectric properties were analyzed by frequency dependent permeability (μ) and permittivity (ε) measurements for the range of 100 Hz to 100 MHz. The conduction process for the synthesized ferrites has been noticed from the ac conductivity (σac). The localized relaxation mechanism for the studied ferrites has been observed from the variation of imaginary portion of the electric modulus (M") and the impedance (Z"). Moreover, the mismatch (Z/ηο) between the impedance of the antenna substrates (Z) made of the studied samples and air (ηο) has been evaluated from the permeability and permittivity. Finally, NiFe2O4 has been derived as a suitable ferrite for miniaturizing devices over a frequency range of 10 kHz-6.5 MHz.

A low‐profile, wideband, circularly polarized, slotted, U‐shaped textile antenna for W‐BAN applications

AbstractWe propose a compact, wideband, U‐shaped, circularly polarized textile antenna (UCPTA) resonating at 2.45 GHz for wireless body area network (W‐BAN) applications. The radiator of the antenna is printed on the top of the substrate (size of mm3; ) and has a full ground plane on the other side. The proposed antenna's substrate consists of a single layer of denim (), and conductive copper tape was used to fabricate the patch. The antenna has a low‐profile design that is suitable for wearable applications. A small slot was introduced at the center of the U‐shaped patch to enhance the 3 dB axial ratio bandwidth (ARBW) up to 55.17%. The proposed antenna radiates with a 10 dB return loss (RL), impedance bandwidth (IBW) of 64.40%, and a simulated gain of 5.1 dBi. The wearable textile antenna with broadside radiation response is appropriate for off‐body communications. The prototype of UCPTA is fabricated for experimental validation. The measured results for the fabricated antenna were in good agreement with the simulated results. Further, it has been demonstrated that the antenna's performance is stable during structural deformation and human body loading. This textile antenna covers an ARBW in the frequency band of 2.1 GHz–3.72 GHz and has a broad IBW (2 GHz–3.9 GHz) for LTE (2.17 GHz), MBAN (2.360 GHz–2.4 GHz), WPAN (2.395 GHz–2.4 GHz), and WLAN (2.4 GHz–2.482 GHz) applications.

High permeability and low loss easy-plane ferrites with multi-ions doped for miniaturized 5G antennas

Ferrites are the desirable candidates for antenna substrates due to their high permeability and low magnetic loss. However, such excellent magnetic properties cannot be maintained in the GHz band due to the Snoek limit. Here, we report a BaCo1.8Zn0.2Fe16O27 (CoZnW) ferrite prepared by doping multiple ions at the lattice (Zn ions) and grain boundaries (Bi/Ca/Si/V ions) of conventional BaCo2Fe16O27 (Co2W) ferrites, achieving a high permeability of 3.3, low magnetic loss tangent of 0.05, and a high figure of merit (FOM=μ′Qf = 66) at 1 GHz, which is much better compared to the previous reports. Moreover, the dimensions of the antenna deploying the multi-ions doped CoZnW are only 52 % of those deploying conventional commercial materials (Fr4) because of its high permeability and low loss. Such a high permeability is attributed to the enhanced saturation magnetization and the reduced anisotropic field achieved by Zn ions modulation. The low magnetic loss is attributed to the reduced damping of domain wall motion and the refined grain size achieved by Bi/Ca/Si/V ions modulation. Our work not only provides a promising candidate for 5G antennas but also uncovers a physical mechanism for the modulation of magnetic properties of ferrites.

Low-cost saw/sinus-tooth-shaped circular microstrip patch antenna for in-space and satellite applications

Antennas operating in S and C bands are crucial in space satellite applications due to their high bandwidth, which facilitates the swift transmission of large data volumes from space vehicles to Earth. These bands are less affected by atmospheric disturbances and exhibit lower noise levels, ensuring uninterrupted and reliable communication between spacecraft and Earth centers. They are essential for satellite-based remote sensing, analyzing surface properties, transmitting high-resolution images, scientific data, and other information. Additionally, they are used for spacecraft control and navigation, enabling precise mission operations. This study emphasizes user-friendly production antennas with different geometries and distinct feeding techniques, demonstrating various design implementations using CST Microwave Studio software. Innovative manufacturing methods such as 3D printing PLA substrates and using copper tape for antenna elements were explored to optimize costs and production processes. Precise cutting of antenna radiation geometries was achieved using the Cricut machine. Experimental validation through reflection coefficient (S11) measurements with a handheld vector network analyzer confirmed the practical application of theoretical foundations. The study’s novelty lies in examining unconventional materials like PLA filament for antenna substrates, exploring fractalization theory for enhancing bandwidth, and discussing advancements in material science with flexible filaments like TPU. These contributions offer insights into user-friendly antenna production, innovative manufacturing techniques, and theoretical explorations in antenna design, enhancing the efficiency and effectiveness of space satellite communication systems.

Development of nano ferrite coated miniaturised jute antenna for wireless applications

In this work, a microstrip patch antenna is designed using a novel Ytterbium doped Cu-Mn Nano ferrite coated jute substrate for S band (2-4 GHz) applications. The prepared material is characterised by structural and electromagnetic properties to examine and analyse the effect of material factors on antenna substrate suitability. The antenna is designed and simulated using Computer Simulation Technology (CST) software. The antenna parameters such as gain are improved by employing super formula and meander line techniques. The fabricated antenna also shows better performance with return loss, Voltage Standing Wave Ratio (VSWR) and gain values.

Development of new lead free ceramic substrate for rectangular patch antenna application in X-band communication

This work introduces the use of Bi0.5Na0.5TiO3 (BNT) ceramic material as substrates for microstrip patch antennas operating within the frequency range of 8-12 GHz. The simulated antenna was constructed using a substrate composed of a synthesized ferroelectric perovskite-based material with a thickness of t=1.02 mm. This study investigated the intricate electromagnetic properties including permittivity, permeability, dielectric loss, magnetic loss, and miniaturization factor. Characterization techniques are used to investigate the crystal structure, local vibrational properties, surface morphology, and elemental composition of the synthesized sample. The reflection loss, return loss, and radiation pattern of the split ring microstrip patch antenna with a rectangular base were calculated using CST Microwave Studio version 2019. The parametric adjustment of the synthesized sample's uniqueness was achieved by modifying its thickness for t=0.7 mm, t=0.9 mm, t=1 mm, t=1.02 mm, and t=1.04 mm.

Thermal characterization of ceramic pills at millimeter waves with a TE01δ cavity resonator

The progress in 5G/6G technology prompts a demand for new materials operating at millimeter waves that can be exploited as substrates for electronic devices or antennas. In particular, a rapid development of millimeter wave band communication technology demands ceramic materials, which could be applied in low temperature cofired ceramic (LTCC) techniques. This kind of ceramics should possess a low dielectric constant (εr), a low loss tangent (tanδ) and a near-zero temperature coefficient. In the view of above, there is an urgent need for accurate and reliable material microwave characterization techniques that can operate at frequencies well above 15 GHz. Due to the fact that the majority of LTCC ceramic materials can be produced in a cylindrical shape, a suitable characterization method exploits a cylindrical resonator operating at a TE01δ mode, which is dedicated to the characterization of low-loss materials also as a function of temperature.

Engineered substrates for metasurface antennas

This letter explores the advantages of additively manufactured substrates with spatially varying electromagnetic properties. These engineered substrates will be constructed using space filling curves (SFC) of various orders. New advanced manufacturing systems such as the nScrypt 3Dn-300, have enabled the rapid fabrication of these SFC substrates. This letter will apply the engineered SFC substrate to the design and fabrication of metasurface antennas. By utilising a SFC to vary the local substrate permittivity, along with the printed conductive patch dimensions, the range of achievable surface impedances can be greatly expanded. This enlarged design space will be leveraged to yield increased gain for a given metasurface antenna size. Methods to characterise the substrate permittivity and conductive ink are discussed along with a complete description of the metasurface antenna design, fabrication and validation process.

Influence of selected parameters of the substrate of a microstrip textile antenna on changes in its resonance frequency under the influence of humidity

Textile antennas are one of the more essential parts of an electronic system incorporated in modern smart garments, used, for instance, for monitoring physiological signals. The article presents the study of the influence of selected parameters of the substrate of a textile microstrip antenna on the changes in its resonant frequency under the influence of changes in humidity. The impact of moisture was investigated for antennas with two different substrates: polyester and cotton. These materials differ significantly in their ability to absorb and release water. The article shows the construction of a measuring stand, measurement results for short and long-term exposure to moisture, and its statistical analysis. The obtained results indicate that textile antennas with a polyester substrate show more stability of the resonance frequency of the antenna compared to the antenna with a cotton substrate, regardless of changes in humidity. It has also been demonstrated that antennas exposed to prolonged, multi-day humidity variations exhibit higher changes in their resonant frequency than antennas subjected to short-term, 1-day variations.

Ultra-conformal epidermal antenna for multifunctional motion artifact-free sensing and point-of-care monitoring

Accurate acquisition of physiological and physical information from human tissue is essential for health monitoring, disease prevention and treatment. The existing antennas with traditional rigid or flexible substrates are susceptible to motion artifacts in wearable applications due to the miniaturization limitation and lack of proper adhesion and conformal interfaces with the skin. Recent advances in wearable radio frequency (RF) bioelectronics directly drawn on the skin are a promising solution for future skin-interfaced devices. Herein, we present a first-of-its kind epidermal antenna architecture with skin as the antenna substrate, which is ultra-low profile, ultra-conformal, ultra-compact, and simple fabrication without specialized equipment. The radiation unit and ground of antenna are drawn directly on the skin with the strong adhesion and ultra conformality. Therefore, this RF device is highly adaptable to motion. As a proof-of- feasibility, epidermal antenna can be freely drawn on demand at different locations on the skin for the development of temperature sensor, skin hydration sensor, strain sensor, glucose sensor and other devices. An epidermal antenna-based temperature sensor can offer accurate and real-time monitoring of human body temperature changes in the ultra-wideband (UWB) range. The results during the monitoring of hydration level with and without stretching show that the epidermal antenna drawn on the skin is motion artifact-free. We also designed an epidermal antenna array employing a horseshoe-shaped configuration for the precise identification of various gestures. In addition, the non-invasive blood glucose level (BGL) monitoring results during the in-vivo experiments report high correlation between the epidermal antenna responses and BGLs, without any time hysteresis. After the prediction of BGL by BP network, all the predicted BGL values are fallen 100% into the clinically acceptable zones. Together, these results show that epidermal antenna offers a promising new approach for biosensing platform.

Design and optimization of metamaterial-based highly-isolated MIMO antenna with high gain and beam tilting ability for 5G millimeter wave applications

This paper presents a wideband multiple-input multiple-output (MIMO) antenna with high gain and isolation, as well as beam tilting capability, for 5G millimeter wave (MMW) applications. A single bow-tie antenna fed by a substrate-integrated waveguide (SIW) is proposed to cover the 28 GHz band (26.5–29.5 GHz) with a maximum gain of 6.35 dB. To enhance the gain, H-shaped metamaterial (MM)-based components are incorporated into the antenna substrate. The trust-region (TR) gradient-based search algorithm is employed to optimize the H-shape dimensions and to achieve a maximum gain of 11.2 dB at 29.2 GHz. The MM structure offers zero index refraction at the desired range. Subsequently, the MIMO system is constructed with two vertically arranged radiators. Another MM, a modified square resonator (MSR), is embedded between the two radiators to reduce the mutual coupling and to tilt the antenna main beam. Herein, the TR algorithm is again used to optimize the MSR dimensions, and to enhance the isolation to a maximum of 75 dB at 28.6 GHz. Further, the MSR can tilt the E-plane radiation by ± 20° with respect to the end-fire direction when alternating between the two ports' excitation. The developed system is validated experimentally with a good matching between the simulated and measured data.

Leaky-wave antenna on substrate-integrated waveguide with radiation pattern controlled by DC voltage

Abstract This paper presents the application of a substrate-integrated waveguide (SIW) for the design of a leaky-wave antenna (LWA). The antenna radiates through a wide slot in the top wall of the SIW structure in the forward direction. The effective width of the slot is varied by changing capacitances of two arrays of varactors connected between slot edges and inserted conducting strips. The radiation pattern of the antenna is by this way controlled by DC bias, which sets the capacitances of varactors. The maximum radiation direction in elevation can be varied within 35° by changing the DC bias from 2 to 12 V. This elevation angle is measured from the broad side direction perpendicular to the antenna substrate. The measured antenna characteristics are in accord with those predicted by simulation. The antenna can be simply fabricated by a planar circuit board technology.

Substrate integrated waveguide-based frequency-tunable self-octaplexing antenna

This communication presents the first-ever substrate integrated waveguide (SIW)-based frequency-tunable self-octaplexing antenna (SOA) for wireless communication. The structure is arranged by implementing eight distinct patches with planar 50-ohm feedlines at the top of the SIW cavity, which realize eight distinct resonant frequencies. Independent tuning of each resonant frequency is achieved by incorporating appropriately allocated pockets in the antenna substrate, which can be filled with solid dielectrics of different permittivity. The obtained tuning range is broad, from 4.76 GHz to 9.82 GHz, with the capability of tuning each port individually. Furthermore, the port isolation (for all ports) that is better than 20.5 dB. The proposed antenna has a realized gain of 3.91, 3.2, 4.05, 4.14, 3.8, 3.37, 3.55 and 3.28 dBi when using Rogers RT-6010 for pocket filling. Furthermore, the antenna provides stable radiation characteristics with precise tuning. The proposed device is suitable for various applications, including multi-standard wireless communications, due to its small size, wide tuning range, consistent radiation patterns, and comparable isolation levels.

Wideband high-gain low-profile series-fed antenna integrated with optimized metamaterials for 5G millimeter wave applications.

This paper presents a series-fed four-dipole antenna with a broad bandwidth, high gain, and compact size for 5G millimeter wave (mm-wave) applications. The single dipole antenna provides a maximum gain of 6.2 dBi within its operational bandwidth, which ranges from 25.2 to 32.8GHz. The proposed approach to enhance both gain and bandwidth involves a series-fed antenna design. It comprises four dipoles with varying lengths, and a truncated ground plane. These dipoles are connected in series on both sides, running in parallel through a microstrip line. The proposed design significantly enhances the bandwidth, which extends from 26.5 to 40GHz. This frequency range effectively covers the 5G bands of 28 and 38GHz. The expedited trust-region (TR) gradient-based search algorithm is utilized to optimize the dimensions of the antenna components, resulting in a maximum gain of 11.2 dBi at 38GHz. To further enhance the gain, modified H-shaped metamaterial (MTM)-based unit cells are integrated into the antenna substrate. The TR algorithm is employed once more to optimize the MTM dimensions, yielding a maximum gain of 15.1 dBi at 38GHz. The developed system is experimentally validated, showing excellent agreement between the simulated and measured data.

Effective Epsilon-Mu-Near-Zero Photonic Crystal with Low-Permittivity Substrate for Broadside-Beam Leaky-Wave Antenna

Effective Epsilon-Mu-Near-Zero Photonic Crystal with Low-Permittivity Substrate for Broadside-Beam Leaky-Wave Antenna