Evolutionary Algorithms Applied to Cross Aperture Coupled Circularly Polarized Microstrip Antenna

This paper presents a single-feed circularly polarized (CP) microstrip antenna achieved by defected ground structure. With the proposed DGS, a new resonant mode is added, which is orthogonal to the original resonant mode. These two modes will have the same magnitude and the 90° time-phase difference by adjusting the DGS dimensions, which contributes to achieve the CP radiation. Both the simulated and measured 10-dB impedance bandwidth of the CP microstrip antenna are 30 MHz, while the 3-dB axial-ratio bandwidth is 6 MHz. The CP gain across the 3-dB AR band ranges from 4.6 to 5.0 dBic.

ABSTRACTNew designs of the circularly polarized micro-strip antennas (CPMSAs) based on tree fractal geometries are proposed, examined experimentally, and compared. The excellent circularly polarized (CP) radiation with minimum axial ratio (AR) of 0.26 dB is achieved by optimization of the key parameters (angle, length, and width) of the fractal trees etched on the ground plane. Parametric study revealed that the fractal tree defected ground structures (FTDGS) are responsible for satisfying the condition of CP operation. The micro-strip antennas with third iterative FTDGS and modified third iterative FTDGS are fabricated on FR4 substrate. The measured 10-dB return loss and 3-dB AR are 99 MHz (2.407–2.506 GHz) and 12 MHz (2.443–2.455 GHz), respectively, with stable gain of 4.52 dBic at 2.45 GHz, for third iterative FTDGS antenna. For modified third iterative FTDGS antenna, measured 10-dB return loss and 3-dB AR are 109 MHz (2.354–2.463 GHz) and 26 MHz (2.386–2.412 GHz), respectively, with gain about 4.62 dBic in the vicinity of center frequency 2.4 GHz. The proposed designs can be good candidates for the unlicensed 2.45 GHz industrial, scientific, and medical (ISM) band applications.

A technique is demonstrated to generate circularly polarized (CP) radiation of the compact diagonally asymmetric‐slotted microstrip patch antennas. Design rules for the single‐feed, compact, circularly polarized microstrip antennas (CPMA) with any arbitrary‐shaped slots along the diagonal directions are first summarized. Four, compact, CPMA with circular‐, square‐, cross‐, and square‐ring‐shaped slots along the diagonal directions are proposed and compared based on a fixed overall antenna size. A compact, CP, cross‐shaped slotted, microstrip antenna is fabricated and measured to verify the proposed technique experimentally. The measured 3‐dB axial‐ratio bandwidth of about 6.0 MHz is achieved with 10‐dB return loss bandwidth of 19.0 MHz while measured gain of the antenna is 4.0 dBic at 930 MHz. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1920–1927, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26959

Combining magnetic and dielectric materials to form a composite can significantly improve its impedance matching and electromagnetic wave absorption performance. Furthermore, composite materials with a core-shell structure hold promise in meeting the demand for lightweight and highly electromagnetic-absorbing properties. In this study, uniform hexagonal flake barium ferrite (BaFe12O19) was prepared using the hydrothermal method. Subsequently, BaFe12O19@PVDF composites were synthesized by the sol-gel method. By adjusting the mass ratio of BaFe12O19 and PVDF, the shell size of the BaFe12O19@PVDF composite material was controlled, and its electromagnetic absorption performance was enhanced. The shell thickness of BaFe12O19@PVDF is 19.64 nm when the BaFe12O19: PVDF mass ratio is 1:1.0, and the optimal impedance matching is obtained at 13.4 GHz. Meanwhile, at a thickness of 1.5 mm, the minimum reflection loss (RLmin) reached -58.04 dB, and an effective absorption bandwidth (EAB) (RL ≤ -10 dB) of 5.53 GHz was achieved within the frequency range of 11.65 to 15.63 GHz and from 16.36 to 17.91 GHz. Besides, the composites with a matching thickness of 3.5 mm show a maximum EAB of 15.90 GHz when the mass ratio of BaFe12O19 to PVDF is 1:1.2. Within the frequency range of 2-18 GHz, the coverage of reflection loss less than -10 dB is 99.38%, almost achieving full coverage. These results demonstrate that BaFe12O19@PVDF composites exhibit excellent electromagnetic-absorbing performances, making them an excellent candidate for electromagnetic wave absorption in 5G communications.

Construction of rGO/MOF-derived CNTs aerogel with multiple losses for multi-functional efficient electromagnetic wave absorber

To use circular microstrip antennas as circularly polarized radiators, perturbations such as slits are added to resolve degeneracy in the fundamental modes. In this paper, posts are inserted between the circular strip and the ground plane and the degeneracy is resolved. the theoretical investigations of this new circularly polarized microstrip antenna are discussed. In the derivation of the theoretical equations, the field is expanded in terms of Green's functions corresponding to the circular cavity region terminated by an admittance boundary. Numerical examples are given for the frequency characteristics of the axial ratio and the input impedance and for the post dimensions to resolve the degeneracy. the radiation patterns and gains are shown for this antenna. the theory has been confirmed by model experiments.

Multiferroic composites of xNi0.8Zn0.2Fe2O4/(1 − x)BaTiO3 (x = 0, 0.1, 0.3, 0.5, labeled NZFO/BTO) with ~100 nm particle size were synthesized via high-energy ball milling and thermal annealing. The X-ray diffraction shows a co-existence of the ferromagnetic phase of NZFO and the ferroelectric phase of BTO. Our observations indicate that saturation, remanence, and coercivity progressively increase with increasing NFO content, specifically from x = 0 to x = 0.5. At x = 0.1, the maximum electric polarization, remanent electric polarization, coercivity and electric power loss density reach their maximum values of ~0.057 µC/cm2, 0.018 µC/cm2, 3.25 kV/cm and 0.222 mJ/cm3, respectively, for an applied electric field less than 10 kV/cm. These multiferroic composites demonstrate excellent electromagnetic wave absorption capabilities from 2 to 18 GHz. With BTNF1 (x = 0.1) sample thickness of 2.5–3.5 mm, a minimum reflection loss of −41.51, −37, −28.72 dB corresponds to frequencies of 12.52 GHz, 11 GHz and 9.32 GHz. The effective absorption bandwidth for this sample is 11.5–16 GHz, indicating optimal impedance and attenuation matching and effective absorption of electromagnetic waves throughout the Ku bands. These outcomes reveal the capability for wideband absorption uses in radar invisibility technology and electromagnetic insulation.

A new technique to design single-feed circularly polarized (CP) microstrip antenna is proposed. The CP radiation is obtained by adjusting the dimension of the etched fractal defected ground structure (FDGS) in the ground plane. Parameter studies of the FDGS are given to illustrate the way to achieve CP radiation. The CP microstrip antennas with the second and third iterative FDGS are fabricated and measured. The measured 10-dB return-loss bandwidth of the CP microstrip antenna is about 30 MHz (1.558 to 1.588 GHz), while its 3-dB axial-ratio bandwidth is 6 MHz (1.572 to 1.578 GHz). The gain across the CP band is between 1.7 and 2.2 dBic.

A new circular‐polarization (CP) design of an annular‐ring microstrip antenna operating at the fundamental TM11 mode is presented. The CP radiation of the proposed design is achieved by connecting an L‐shaped strip to two orthogonal sides of the inner boundary of the annular‐ring patch. A prototype of the proposed antenna fabricated on a foam substrate has been implemented and studied. The results show that good CP‐radiation performances are obtained and the 3‐dB axial ratio is about 2%. Good agreement is also obtained between the measured and simulated results. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 42: 156–157, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20237

In this paper, a binary coded anomalous reflector with near-field correction technique is proposed for generation of directive beam from a dipole antenna. The proposed anomalous reflector of dimension 10λ0 � 10λ0 operates at f=5.9GHz and is capable of simultaneously correcting for near-field effects, while characteristically bearing a phase gradient to steer the main beam towards a designed angle of 45°. First, the phase gradient for far-field incidence is computed using generalised Snell's law. Next, the phase gradient is modified accordingly to correct the near-field effects due to the radiator placed at λ0/4 above the anomalous reflector. The proposed anomalous reflector is designed on an FR-4 substrate. The primary radiator is a printed dipole with integrated balun matched to 50 Ω. The dipole is designed on RT Duroid substrate of thickness 0.508mm. The placement of dipole with anomalous reflector along two orientations is studied for Gain and HPBW, and is compared to a dipole with PEC bearing the same dimensions. The dipole is individually optimised with both the PEC and the anomalous reflector to achieve optimum S11 and impedance matching. For the anomalous reflector with dipole, a peak gain of 14.8 dBi is observed while consequently steering the beam at 45°. The proposed dipole backed with near-field corrected anomalous reflector can be employed in applications like Vehicle to Vehicle (V2V) or Vehicle to Everything (V2X) networks. © 2024 IEEE.

In this paper, a compact dual feed circularly polarized microstrip antenna (CPMSA) is presented using 3-dB 2-branch line coupler as feed network. The antenna size is reduced by 39.9% by cutting slots in circular shaped CPMSA. The antenna characteristics are analyzed using cavity enclosure and radome cover. It increases the antenna bandwidth (BW) and gain. The compact CPMSA provides 26.8% BW for |S 11 | ≤ -10 dB and 3 dB axial ratio (AR) BW of 27% with maximum gain of 6.9 dBi at 2.8 GHz. Cross polarization (X-pol) of lower than -15 dB and front to back ratio (FBR) of more than 12 dB are obtained for the compact CPMSA. The designed antenna is fabricated and experimental results agree well with simulated results. The designed antenna can be used as transmitter and receiver in transponder systems to monitor missile health parameters.

In a pioneering effort, this research presents a distinctive transformation of the Government College University Faisalabad (GCUF) logo into an RFID tag antenna using characteristic mode analysis (CMA), which resonates at the entire ultra-high frequency (UHF) radio frequency identification (RFID) band for IoT applications. The logo of GCUF is simulated in a computer simulation technology (CST) microwave studio to execute its four characteristic modes at 900 MHz. With the implementation of minor changes in the GCUF logo, optimal conjugate impedance matching with the RFID chip has been achieved. The impedance, reflection coefficient, and far-field pattern are examined through CST. The logo tag antenna is fabricated using a Rexin substrate (artificial leather) coated with conductive paint and a passive UHF RFID Alien Higgs H3 chip attached to the logo for impedance matching. The proposed design has been simulated with a human body model. The read range of the fabricated prototype is tested on different objects, like a notebook, T-shirt, and bag. The measured read range demonstrates the robustness of the proposed logo design across various distances: 3 m for a notebook and bag, and 2 m for a T-shirt, with RSSI values of −61 dB, −59 dB, and −62 dB, respectively.

A simple design of a probe-feed microstrip antenna with circular polarization (CP) radiation is presented. By embedding dual slits in a square microstrip and adjusting the sizes of the slits, an H-shaped microstrip antenna with two near-degenerate orthogonal modes for CP radiation can be achieved. This design provides a wide CP bandwidth and relaxed fabrication tolerances. Details of the antenna design are described, and theoretical and experimental results of the CP performance are presented.

MOF derived porous Ni/Co@C nanocomposite as electromagnetic wave absorber with optimized impedance matching

This paper proposes new design of square microstrip antenna with dual feed line for improving bandwidth and axial ratio at work frequency of 2400 MHz. To obtained circular polarization with axial ratio ≤ 3 dB and enhanced bandwidth of antenna, dual feed line is used to improve performance of conventional microstrip antenna. After the simulation process, dual feed line succeed to improved bandwidth of microstrip antenna 131.9 % compared with microstrip antenna with single feed and provide circular polarization with axial ratio 2.44 dB at working frequency of 2400 MHz. compared to the microstrip antenna with a single feed. This research is very usefull for Wi-Fi application in order to improve the level quality of receiver signal.