Antenna Substrate Research Articles

Polydimethylsiloxane as a Potential Antenna Substrate

Polydimethylsiloxane as a Potential Antenna Substrate

Bend and Moisture Effects on the Performance of a U-Shaped Slotted Wearable Antenna for Off-Body Communications in an Industrial Scientific Medical (ISM) 2.4 GHz Band.

In recent years, the study and design of wearable antennas have been empowered given the success of Wireless Body Area Networks (WBAN) for healthcare and medical purposes. This work analyses a flexible textile antenna whose performance can be optimised by the careful selection of the substrate thickness of the textile material, and by varying the antenna’s geometrical shape. After considering these parameters, several arrangements of antennas were simulated using the Computer Simulation Technology software (CST). The results of the simulations were compared to the experimental prototypes manufactured on a flexible felt material for a range of thicknesses and curvatures of the antenna substrate. Such antenna designs can be utilised in off-body communications and ISM applications.

IMPLEMENTASI JARINGAN SYARAF TIRUAN DALAM MEMPREDIKSI FREKUENSI RESONANSI ANTENA MIKROSTRIP

The resonant frequency of an antenna is determined by the dimensional parameters and permittivity of the antenna substrate. Generally, to get the resonant frequency, a complex mathematical formula is needed to solve. For this reason, an intelligent method is offered to determine the resonant frequency more easily. In this study, an artificial neural network method with Backpropagation algorithm is used to overcome the problem. The data used were consisting of 80 training data and 15 testing data. The results have shown that the artificial neural network learning method with the backpropagation algorithm was successfully utilized to calculate the resonant frequency of microstrip antennas, where the precision of the resonant frequency obtained of 93.33% at an error of = 1%, and 100% at an error of = 2%.

Design of a fractal inspired antipodal vivaldi antenna with enhanced radiation characteristics for wideband applications

A novel fractal inspired antipodal Vivaldi antenna is proposed for wideband applications. A step-by-step procedure has been employed to design and optimise the performance of the proposed antenna. First, a conventional antipodal Vivaldi antenna (CAVA) is designed as a reference antenna and then a Koch fractal-shaped parasitic lens is introduced in the CAVA. Finally, a fractal-shaped dielectric lens has been added as an extension of the antenna substrate. The presence of parasitic fractal lens in the flare aperture and fractal dielectric lens enhances the antenna bandwidth and also improves field coupling between the antenna arms and produces stronger radiation in the end fire direction which in turn increases the gain and directivity of the antenna. The optimised antenna is fabricated and tested showing| S 11 | below -10 dB from 4.2-42 GHz band. The dimension of the proposed antenna is 186 × 66 × 1.524 mm 3 . Results show that |S 11 | characteristics and other parameters are in good agreement with the simulation counterpart.

MM-Wave Phased Array Quasi-Yagi Antenna for the Upcoming 5G Cellular Communications

The focus of this manuscript was to propose a new phased array antenna design for the fifth generation (5G) mobile platforms. Eight elements of compact Quasi-Yagi antennas were placed on the top portion of smartphone printed circuits board (PCB) to form a beam-steerable phased array design. The −10 dB impedance-bandwidth of proposed 5G smartphone antenna spans from 25 GHz to 27 GHz providing 2 GHz bandwidth with less than −16 dB mutual coupling function. A coax-to-microstripline with a truncated crown of vias around the coaxial cable was used as a feeding mechanism for each radiation element. An Arlon Ad 350 substance with properties of ε = 3.5, δ = 0.003, and h = 0.8 mm was chosen as the antenna substrate. The proposed phased array antenna provides wide-angle scanning of 0°~75° with more than 10 dB realized gain levels. For the scanning angle of 0°~60°, the antenna array provides more than 90% (−0.5 dB) radiation and total efficiencies. In addition, the specific absorption rate (SAR) function and radiation performance of the design in the presence of the user-hand/user-hand have been studied. The results validate the feasibility of the proposed design for use in the 5G handheld devices. Furthermore, using the presented Quasi-Yagi elements, the radiation properties of 2 × 2, 4 × 4, and 8 × 8 planar arrays were studied and more than 8.3, 13.5, and 19.3 dBi directivities have been achieved for the designed planar arrays. The results show that the designed arrays (linear & planar) satisfy the general requirements for use in 5G platforms.

Bi2O3 adjusting equivalent permeability and permittivity of M-type barium ferrite for antenna substrate application

In this paper, Co-Ti doped M-type barium ferrite [Ba(CoTi)1.22Fe9.56O19] was prepared at low temperature (925 °C) in O2 atmosphere with different amounts of Bi2O3 sintering additive (x = 5–14 wt%). XRD showed superfluous Bi2O3 additive led to BiFeO3 phase formation, which is the important factor to adjust properties of material. SEM revealed that the grain size diminished gradually. For magnetic and dielectric properties, with different amounts of Bi2O3, saturation magnetization (Ms) decreased and coercivity (Hc) gradually increased. Complex magnetic permeability and dielectric permittivity presented excellent regularity, and the equivalent permeability and permittivity were obtained when x = 5 wt%. At x = 5 wt%, the real part of permeability (μ′) and permittivity (ε′) were about 18.3 at a range of 10 MHz–1.0 GHz, the magnetic loss (tan δμ) was about 3.4 × 10−2, and the dielectric loss (tan δε) was about 2.8 × 10−3. It showed that Bi2O3 not only lowered the sintering temperature of ferrite, but also adjusted the magnetic and dielectric properties, and the material has potential to apply for miniaturizing efficient antennas at high frequency.

Investigation of Micromachined Antenna Substrates Operating at 5 GHz for RF Energy Harvesting Applications.

This paper investigates micromachined antenna performance operating at 5 GHz for radio frequency (RF) energy harvesting applications by comparing different substrate materials and fabrication modes. The research aims to discover appropriate antenna designs that can be integrated with the rectifier circuit and fabricated in a CMOS (Complementary Metal-Oxide Semiconductor)-compatible process approach. Therefore, the investigation involves the comparison of three different micromachined antenna substrate materials, including micromachined Si surface, micromachined Si bulk with air gaps, and micromachined glass-surface antenna, as well as conventional RT/Duroid-5880 (Rogers Corp., Chandler, AZ, USA)-based antenna as the reference. The characteristics of the antennas have been analysed using CST-MWS (CST MICROWAVE STUDIO®—High Frequency EM Simulation Tool). The results show that the Si-surface micromachined antenna does not meet the parameter requirement for RF antenna specification. However, by creating an air gap on the Si substrate using a micro-electromechanical system (MEMS) process, the antenna performance could be improved. On the other hand, the glass-based antenna presents a good S11 parameter, wide bandwidth, VSWR (Voltage Standing Wave Ratio) ≤ 2, omnidirectional radiation pattern and acceptable maximum gain of >5 dB. The measurement results on the fabricated glass-based antenna show good agreement with the simulation results. The study on the alternative antenna substrates and structures is especially useful for the development of integrated patch antennas for RF energy harvesting systems.

Increased Flexibility in Polyimide Aerogels Using Aliphatic Spacers in the Polymer Backbone.

Polyimide aerogels are mechanically strong porous solids with high surface area, low density, and dielectric constants close to 1, making them ideal materials for use as substrates for lightweight antennas. Increasing the flexibility of the polyimide aerogels extends the usefulness for conformal antennas for use on small aircraft such as unmanned air vehicles or personal air mobility vehicles. To this end, polyimide aerogels made with aromatic amines with 4-10 methylene units as flexible spacers between aromatic rings in the backbone have been fabricated. Substituting 25-75 mol % of fully aromatic 2,2'-dimethylbenzidine with these flexible diamines increases the flexibility of polyimide aerogels, making them bendable at thicknesses up to 2-3 mm. The density, dielectric constants, thermal and moisture stability, and mechanical properties of these aerogels were assessed to understand the effect of the amount and length of the methylene spacers on these properties.

Preparation of Flexible Substrate for Patch Antenna Based on Nickel Aluminate (NiAl2O4) Synthesized by Sol–Gel Method

In this study, a flexible substrate for a patch antenna based on nickel aluminate (NiAl2O4) synthesized by the sol–gel method is presented. Nano-crystalline NiAl2O4 is synthesized by many researchers with several methods, but they have not been explored much for microwave applications. The microwave dielectric properties of NiAl2O4 were investigated to find their employment as an antenna substrate for microwave wave uses. The sol–gel method was employed to synthesize the flexible composite. The establishment of spinel assembly and crystalline dimension were assured using x-ray diffraction analysis. Morphology of the samples was clarified by means of the scanning electron microscopy. Relative permittivity and dielectric loss tangent of the specimen were restrained by a DAK 200 MHz to 20 GHz dielectric measurement kit and obtained as 4.8 and 0.04, respectively. The energy bandgap was found to be 2.8 eV from optical analysis, which implies that the synthesized nanoparticles are semiconductors by nature. The substrate layer was prepared by mixing NiAl2O4 nano-powder with polyvinyl acetate glue dried up by means of heat. The compatibility of the prepared substrate material for making a microstrip patch antenna is investigated by utilizing the finite-difference method based on a computer simulation technology microwave studio. Finally, the patch antenna is fabricated on NiAl2O4 flexible composite substrate employing 200 nm copper coating over that 1 mm thick substrate by magnetron sputtering to the simulation process following the simulation process, which showed outstanding performances, measured through a N5227A PNA microwave network analyzer and offers a wide band of operating frequency of 8–15 GHz in X-band and Ku-band of microwave frequency spectra. The operating band of frequency can be arbitrarily chosen by modifying substrate and/or radiating elements. The simulated and measured results are matched satisfactorily.

UWB Metamaterial-Loaded Antenna for C-Band Applications

A novel metamaterial-inspired patch antenna is proposed, wherein a 2-segment SRR Labyrinth metamaterial is embedded inside the antenna substrate. It is observed that upon incorporation, the bandwidth widens to around 600% and VSWR improves by approx. 1.5% and the antenna is miniaturized by 400%. The Nicolson-Ross-Weir (NRW) method has been used to retrieve the material parameters from transmission and reflection coefficients.

Micro-strip antenna with high bandwidth, cone pattern, circular polarization, and slit

ABSTRACTThis paper presents a micro-strip antenna with cone pattern, circular polarization, and optimized impedance dimensions and bandwidth. It consists of an antenna radiation plane (patch), two Lange couplers dividing the Wilkinson power, and a circular substrate including defected ground structure elements. Scattering and pattern of the proposed antenna are measured after optimization. Also, a circular micro-strip antenna with a slit is designed. This antenna results in an increase of 32% in impedance bandwidth and a decrease of 44% in the antenna dimensions because of slitting the radiation plane (patch) and circulating the substrate antenna construction and substrate antenna feed. Finally, the simulation result and practical measurements demonstrate the validity of the proposed antenna for practical applications.

Ultra Low-Loss Si Substrate for On-Chip UWB GHz Antennas

In this paper, measurements and simulations of miniature monopole antennas for ultra-wideband (UWB) GHz intra- and inter-chips communication and biomedical applications are presented. Folded designs on four substrates are studied: 1) standard bulk; 2) high-resistivity bulk; 3) ultra low-loss radiofrequency silicon-on-insulator (RF SOI); and 4) quartz. Among the Si-based substrates, RF SOI with its trap-rich sublayer demonstrates the best performances with the lowest RF power losses and centimetric transmission distance between antennas. Transmitted power between two antennas was measured from 0.01 to 20 GHz. Using substrate characterization of resistivity, permittivity, and loss tangent based on measured coplanar waveguide lines on the same substrates, good agreement is obtained between the return losses of simulated antennas on each substrate and numerical solutions, confirming the impact of the substrate properties. An antenna bandwidth of 680 MHz is demonstrated at 6.0 GHz meeting the criterion for UWB radio communications in the 6–10 GHz band.

U-slot patch antenna with low RCS based on a metaferrite substrate

Metamaterial ferrites or metaferrites are artificial magnetic materials which mimic the properties of ferrites at a certain frequency operation. Antenna engineers are therefore able to design and create artificial substrates which replicate the electrical properties of ferrites without actually using any in the construction. This is advantageous as ferrites can offer performance improvements to microstrip antennas, such as size reduction and wideband impedance matching. In this paper, a metaferrite substrate designed by the use of a genetic algorithm is presented. The metaferrite was optimized in order to obtain the magnetic responses at 9GHz, for its use as the substrate of a microstrip antenna. As an example, a U-slot patch antenna based on the metaferrite is demonstrated, which can achieve stable radiation and 14 dB radar cross section (RCS) reduction performance in the measurement.

Design of Ultra-Wide Band Metal-Mountable Antenna for UHF Partial Discharge Detection

This paper presents an ultra-wideband metal-mountable antenna used in the ultra-highfrequency (UHF) partial discharge (PD) detection. The designed antenna combines a coplanar waveguide antenna and multilayer substrates to effectively broaden its bandwidth when mounted on a conductive surface. These substrates consist of two layers of FR-4 dielectric substrates and two layers of the absorbing gasket, which is adapted to absorb the reflected electromagnetic signals. The parametric study is conducted to optimize antenna performance. A prototype is fabricated to confirm the design, and the measurement results show good agreement with the simulation. When mounted on the metal plate, the proposed antenna covers the UHF bandwidth of 400 MHz-3 GHz for S 11 <; -10 dB with a compact size (282 mm × 242 mm × 8.75 mm). As the thickness of the antenna is only 8.75 mm, the safety distance of electric insulation in electrical equipment will not be affected. A PD experiment has been carried out, and a reference antenna is used in the experiment for comparison. Compared with the conventional antenna, the proposed antenna has a better performance when mounted on the metal plate. It is shown that the designed antenna is a very good candidate for UHF PD detection inside of high-voltage equipment.

Polarization Reconfigurable Air-Filled Substrate Integrated Waveguide Cavity-Backed Slot Antenna

The Internet of Things requires highly efficient ultra-wideband antenna systems that yield high performance at low manufacturing cost. Therefore, a novel ultra-wideband circular air-filled substrate-integrated-waveguide (AFSIW) cavity-backed annular slot antenna is proposed that enables straightforward integration into general-purpose materials by means of standard manufacturing techniques. The cavity top plane, serving as antenna aperture, contains two concentric annular slots, both split into two by shorting tabs that create a virtual electric wall. This enables the generation of a TE11,slot even mode in both parts of each annular slot, giving rise to a conical radiation pattern. By exciting two such modes and judiciously positioning their resonance frequencies, all the unlicensed national information infrastructure (U-NII) [5.15-5.85] GHz radio bands are covered. The annular slot antenna is then made polarization reconfigurable through an innovative excitation of the slot modes by replacing the shorting tabs with four pairs of the PIN diodes. These dynamically switch between two orthogonal linear polarizations by changing the dc control current at the antenna RF port through an external bias tee. This simple, yet effective, bias network enables the integration of all polarization control electronics inside the antenna cavity to protect them from environmental effects. A low-cost antenna substrate was realized through standard additive manufacturing in a 3D-printed substrate, while a standard high-frequency laminate was used to implement the upper conducting plane containing the radiating elements and the polarization reconfiguration electronics. The antenna features an impedance bandwidth of 0.93 GHz, a front-to-back ratio of 14 dB, a total antenna efficiency higher than 95%, and 4.9 dBi gain for each polarization state.

Compact antipodal Vivaldi antenna with rectangular slots and shaping of flare to cover 6 to 18 GHz

ABSTRACTThe compact antipodal Vivaldi antenna (AVA) with regular rectangular slots in the taper region is presented in this paper intended for electronic warfare applications. The antenna has a simple configuration with compact size. Micro strip line feeding is employed. The rectangular slots at regular intervals and terminal elliptical shaping of taper on top and bottom layers of antenna substrate enhance impedance bandwidth. The slot loading in the taper portion also enhances the gain. The novel feature of this antenna is its small aperture size which is 25 mm. Small aperture size is required for array applications to avoid grating lobes and element pattern nulls. A return loss of less than −10 dB (VSWR <2.0) is obtained over 6 to 18 GHz. The antenna is designed using Ansoft HFSS software and the same is implemented in hardware. Return loss, radiation patterns, and gain have been measured and results reported.

Wearable UHF RFID Sensor-Tag Based on Customized 3D-Printed Antenna Substrates

The combination of radiofrequency identification (RFID) technology with 3D-printed structures is very appealing to design new RFID-based smart but cost-effective devices. In this paper, two different 3D-printed devices in the RFID framework are designed, realized, and tested. In particular, since permittivity and loss tangent of the printed substrate depend on the volume fraction of air in the host material, the first proposed device is purposely a T-resonator-based system suitable for the dielectric characterization of 3D-printed substrates in UHF RFID band, realized in 3D-printing technology itself. Based on the obtained results, the second device is a compact 3D-printed wearable antenna feeding a UHF RFID sensor tag designed to passively sense and retrieve the human body temperature. Both devices have been realized by combining 3D-printed plastic elements and conductive parts and then tested so to demonstrate the aptness of 3D-printing technology in designing RFID devices.

Beam‐ and polarisation‐reconfigurable SIW ring‐slot antenna array

A beam- and polarisation-reconfigurable substrate integrated waveguide (SIW) ring-slot antenna array is proposed in this study. The 2×2 ring-slot antenna array can generate beams in four different directions in two orthogonal linear polarisations (LPs). This is achieved by a feeding network consisting of four 90° SIW 3 dB couplers arranged in a multilayer structure for a compact antenna size of 131.6 mm × 65.8 mm × 4.9 mm. The antenna elements' LP plane is controlled by PIN diodes, switched by a DC bias network integrated on the antenna substrate. The proposed antenna array is designed for the 5.8 GHz industrial, scientific and medical (ISM) frequency band and verified by measurements. Experimental results validate good impedance matching over the entire frequency band as well as the beam and polarisation reconfigurability.

Microwave sintered Mg-Cd ferrite substrates for microstrip patch antennas in X-band

The ferrites with chemical formulae MgFe2O4, Mg0.6Cd0.4Fe2O4 and Mg0.2Cd0.8Fe2O4 specified with Ferrite S1, S2 and S3 were prepared by the oxalate co-precipitation method using AR grade sulphates under microwave sintering technique. The single phase cubic spinel structure formation of all the ferrites was confirmed by XRD and FTIR techniques. The dielectric parameters such as permittivity (εr), dielectric loss tangent (tan δe), permeability (µr) and magnetic loss tangent (tan δm) were determined from parameters S11 and S21 by using material measurement software with VNA. The synthesized ferrites S1, S2 and S3 with determined dielectric parameters were used as substrate to design rectangular microstrip patch antenna by simulation using Ansoft Designer SV 2.2. The designed antennas were fabricated by using screen printing technique. The return loss (RL), 10 dB % bandwidth and VSWR of these fabricated antennas were measured on vector network analyzer. The simulated and measured values of resonating frequency, return loss (RL), 10 dB % bandwidth and VSWR were nearly matched with each other. Mg0.2Cd0.8Fe2O4 (Ferrite S3) can be used as substrate of antenna for better results.

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