In this work, we present numerical results regarding the effects of temperature on the omnidirectional photonic band gap (OPBG) of ternary 1DPC containing metal (Ag) layer or graphene layer. By periodically introducing layer metal (Ag) or graphene into 1DPC, the width of OPBG has been increased. As the temperature increases, the photonic band gap of the OPBG becomes wider. Compared to the conventional OPBG in ternary 1DPC containing Ag, the OPBG in 1DPC containing graphene with temperature T = 1000˚K is greatly broadened by 2.04 times. The theoretical basis of our study adopts the transfer matrix method TMM. In fact, these broad omnidirectional and thermally tunable OPBGs will offer many prospects for omnidirectional mirrors, temperature sensing device, optical filters, polarizer, and other optical devices.
This paper presents a dual-band dual-polarized antenna including one L-band vertically polarized antenna, four C-band horizontally polarized subarrays and four C-band vertically polarized subarrays. Both the L- and C-band radiation elements are designed based on the concept of slotted coaxial waveguide antenna. The coaxial waveguide structure is in rectangular shape which is suitable for multi-element integration. And bending stripline inside the waveguide cavity plays the role of inner connector for the coaxial waveguide and exciter for radiating slots on the waveguide. Results show that impedance bandwidths of 14.9% for L-band and 5.9% for C-band are obtained with good port isolation. The antenna also exhibits good radiation performance with the low cross-polarization. The results indicate that the proposed antenna is suitable for synthetic aperture radar applications.
This work presents a design and analysis of a high gain Antipodal Vivaldi Antenna (AVA) with quad band notch characteristics for Ultra-Wideband (UWB) applications. The proposed AVA is designed on a 1.2 mm FR4 substrate with dielectric constant 4.3 and loss tangent 0.025. Initially, the AVA parameters are optimized in a full wave simulator to get the required UWB performance. The UWB performance is further improved significantly by cutting a C shaped slot from the AVA flares. The C shaped slot introduces an extra resonance that widens the initial bandwidth. The band-notched filtering characteristics are achieved by - adding a Sun Shaped Slot (SSS) on the top and bottom flares of the AVA, inserting a hexagonal shaped Complimentary Split Ring Resonator (CSRR) on the ground plane of the AVA and finally by inserting vias on either side of the feed line. The first designed notch band is from 2.2-2.7 GHz, covering the Bluetooth region. The second notch band is designed from 3.3-3.6 GHz, corresponding to WiMAX applications, and the third notch band is from 4.6-5.7 GHz corresponding to the WLAN band. Finally, a notch is fashioned from 8.8-9.5 GHz, corresponding to ITU applications. The simulated and measured return loss plots show that the antenna achieves an impedance bandwidth of 1.15-14 GHz with a reflection coefficient less than -10 dB, except at the four eliminating bands. To the best of the authors knowledge, the proposed technique is novel, and it allows good narrowband rejection over the UWB regime.
In this paper, we propose a wideband polarization diversity multiple-input multiple-output (MIMO) antenna array for 5G smart mobile devices. The proposed MIMO antenna array consists of 8-ports dual-polarized L-shaped lines that highly excite radiating slots, where the elements are placed at four-corners of a compact mobile unit of size 75×150 mm2. The uniqueness of the proposed MIMO antenna structure comes from the deployment of octagon-shaped resonant slots within the metallic ground plane, i.e. the octagonal-slots are etched from the bottom (ground) layer of the main mobile board. Due to the unique slots in the ground plane, wideband impedance has been achieved (3.38-3.8 GHz at -6-dB threshold). The proposed smart phone 8×8 diversity MIMO antenna is designed to support the spectrum of commercial sub-6 GHz 5G communications and cover the frequency range of around 3.5 GHz band with high decoupling between antenna ports. The proposed array is designed, numerically simulated, fabricated and tested. Good agreement between simulated and measured results was achieved. The MIMO antenna has a satisfactory far-field performance along with very low envelope correlation coefficient (ECC) < 0.055, high diversity of more than 9.95, and very low specific absorption rate (< 1 W/Kg for a 10-g human tissue).
One of the common ways to design large arrays is by designing a small subarray known as cluster and using it as a repeating element throughout a large array. In this paper, the genetic algorithm is used to optimize the clustered amplitude tapers such that the final array pattern has minimum grating lobes and controlled sidelobe level. The formulation of the synthesis problem includes the minimization of the excess magnitude of the grating lobes or peak sidelobes which are usually higher than a given allowable limit. Moreover, two clustered configurations based on increased/decreased number of elements per cluster around the array center are introduced. Correspondingly, their clustered sizes increase/decrease as they approach the center of the array. Simulation results show that the proposed method has capability to optimize clustered linear and planar arrays without noticeable appearance of undesirable grating lobes. The analysis for an array composed of 20 elements with clusters of different cluster sizes M = 10, 8, 5, 4 and different numbers of elements per cluster Ns = 2, 3, 4, 5 elements found that the complexity reductions were 50%, 60%, 75%, 80%; peak sidelobe levels were -29 dB, -23.6 dB, -21.3 dB, -19.15 dB; and the directivities were 25.53 dB, 25.64 dB, 26.33 dB, 26.32 dB, respectively.
It is of great practical value to study the blended rolled edge of reflector used in Compact Antenna Test Range (CATR). Taking a rectangular aperture reflector as the benchmark, a reflector with ideal blended rolled edge is obtained by means of parameter iterative optimization after accurately establishing the position relationship between the local and global coordinates where the blended rolled edge is located, precisely deriving the geometric equation of the main reflector zone and blended rolled edge zone in the local coordinate, and optimizing continuity condition of curvature radius. On the basis, a blended rolled edge reflector with minimum operating frequency of 0.8 GHz and quiet zone size of 2 m is designed. The simulation results show that the performance of the reflector with blended rolled edge obtained by the proposed method is better than that obtained by the traditional construction method, and the designed reflector has excellent performance. The work in this paper provides a theoretical support for the optimal design and engineering application of the blended rolled edge reflector.
In the medical world, the continuous monitoring of patients having a long-term illness is mandatory. The usual monitoring systems placed around the patients are bulkier and costly. Moreover, the movement of those patients is limited as they are connected to the monitoring devices with probes. To enable the locomotion of the patients a miniaturizedimplantable antenna sensor with the dimension 2.5 x 7 x 0.25 mm3 is proposed to monitor arterial pressure. The proposed antenna sensor is fabricated and verified for its performance metrics. Radiation analysis for the implants is carried out through a metric called Specific Absorption Rate (SAR). Deviation of pressure in the patient is measured through the rate of change of resonant frequency through an external reader coil. Communication established between the Transmitter (patient with implant) and the Receiver for better monitoring is verified through field strength calculated at various locations inside the hospital rooms in order to allocate rooms for the post-operative/long term ill patients efficiently.
In this paper, a compact UWB antenna with a reconfigurable and sharp dual-band notches filter to cancel the interference with some critical applications (5G WLAN, and X-band satellite downlink) is proposed for underlay cognitive radio (CR) applications. The dual notched bands are produced by coupling a pair of π-shaped resonators on both sides of the feed line and by etching a U-slot inside the feed line of the antenna. The proposed UWB filtenna in this configuration has a surface area of 22×31 mm2 and produces simulated (measured) reconfigurable notched frequencies at 5.466 GHz (5.7 GHz) and 7.578 GHz (7.44 GHz) with an impedance bandwidth of 3.024-10.87 GHz (2.825-10.74 GHz). Three PIN diodes are used to switch the presence of the dual-band notch. Two PIN diodes turn ON-OFF simultaneously (D1A & D1B) are inserted within a pair of π-shaped resonators to control the 5G WLAN band notch, and a single diode (D2) is embedded within a quarter wavelength resonator which is located inside the feed line of the antenna for controlling the X-band band notch. The simulation and measured results reveal that the proposed filtenna effectively covers UWB with controlled cancellation for the interference with the intended bands. The realized gain is 4.5 dBi through the passband except in the notched frequencies, where it is decreased to less than -11 dBi in both notch frequencies. In other words, the proposed filtenna has a very high VSWR of greater than 20 at the notched frequencies.
The purpose of this study is to embed an antenna on very thin textile materials. A rectangular Fractal Antenna is chosen for this application. This antenna radiates for three different frequencies viz. 2.4 GHz, 4.2 GHz and 5.9 GHz. The substrate materials used for three antennas are Poly Viscous, Poly Cotton and Linen which are easily available. Instead of using traditional method applying copper plate or copper layer on substrate material, a simple process of pasting carbon conductive ink on substrate materials is used. On each textile antenna above mentioned frequencies are radiated. Performance parameters of all three antennas are simulated and matched with practical results. The optimum antenna having the best result is used for Wi-Fi Applications.
Wearable antenna is one component needed for mid-range communication. It can be integrated into clothing, bags, or any other item worn. This paper presents the structure and performance of a wearable antenna used in place of the ESP8266 Wi-Fi module antenna in dresses. With a higher gain than 2 dBi, this replacement will provide greater signal coverage than the existing Wi-Fi antenna module. The proposed geometry utilizes rectangular patches with the inset feed method in the feedline segment, constructed using copper foil tape, 2.85 mm thick polyester as a substrate with a permittivity (εr) of 1.44, and Defected Ground Structure (DGS) technique. The operating frequency of the proposed antenna is at 2.4 GHz in ISM (Industrial, Scientific, and Medical) band. The whole process was used to optimize the structure, fabricated, and measured. As determined by simulation, the proposed antenna's return loss is -13.89 dB, whereas the measured value is -13.253 dB. The measurements scenario for the substitute and existing antenna are divided into two categories: line-of-sight (LoS) and non-line-of-sight (NLOS). Each of them experiences vertical and horizontal position of antenna. In LOS conditions, the vertical position has an average coverage of 9.84 meters more than the antenna module and the horizontal position is 13.84 meters. In NLOS conditions, the horizontal position has an average coverage of 9.22 meters more than the EP8266 antenna module, which in the vertical condition is about 17.06 meters. The obtained data successfully demonstrated that the proposed antenna could significantly increase the coverage of the ESP8266 module.
A novel reconfigurable sub-6 GHz microstrip patch antenna operating at three resonant frequencies 3.6, 3.9, and 4.9 GHz is designed for 5G applications. The proposed antenna is constructed from metamaterial (MTM) array with a matching circuit printed around a printed strip line. The antenna is excited with a coplanar waveguide to achieve an excellent matching over a wide frequency band. The proposed antenna shows excellent performance in terms of S11, gain, and radiation pattern that are controlled well with two photo resistance. The proposed antenna shows different operating frequencies and radiation patterns after changing the of photo resistance status. The main antenna novelty is achieved by splitting the main lobe that tracks more than one user at same resonant frequency. Nevertheless, the main radiation lobe can be steered to the desired location by controlling the surface current motion using two varactor diodes on a matching circuit.