Advanced Electromagnetics

Wideband E-shaped Patch Antennas for Advanced Wireless Terminals

Y. Rahmat-Samii, J. M. Kovitz — Mon, 20 Mar 2023 00:00:00 +0100

Low-profile patch antennas have become ubiquitous in wireless terminals, especially as devices have become smaller and demand more functionality out of their RF subsystems. While their shape and size is attactive for many applications, their narrow bandwidth hinders their usage in many systems. With the rise of computer-aided design, many patch antenna design concepts have been presented with enhanced bandwidth capabilities. The E-shaped patch antenna, whose original shape presented in the early 2000’s resembles the letter E, offers compelling performance with reasonable manufacturing complexity. In it most basic form, this antenna was linearly polarized and either wideband or dual-band. Over the last two decades, many variations of the E-shaped patch have been presented in literature: circularly polarized, miniaturized, frequency reconfigurable, or even polarization reconfigurable. This paper summarizes these efforts in realizing novel functionalities with a relatively simple design geometry.

A Typical Slotted SIW Cavity-backed Antenna for Dual frequency operations in U-NII Bands

R. Sengupta, S. Banerjee, M. Mitra — Sun, 21 May 2023 00:00:00 +0200

A low profile circular shaped cavity-backed substrate integrated waveguide (SIW) antenna with two-typical intersecting rectangular slots on the ground plane is designed to operate in the dominant TM010 mode at a frequency of 5.19 GHz in U-NII-1 band for wireless applications. The initially designed antenna produces a gain of 4 dBi with a narrow impedance bandwidth extending from 5.17 – 5.22 GHz. The antenna design is further modified by insertion of another shifted two-typical intersecting rectangular slots to finally resemble that of Hash shape; resulting in dual band antenna operation at 4.9 and 5.93 GHz. The gains obtained are 3.7 dBi and 1.4 dBi for 4.9 and 5.93 GHz respectively with an impedance bandwidth covering 4.88 - 4.92 GHz and 5.92 – 5.94 GHz respectively. The antenna prototype is fabricated using Arlon AD270 substrate material. Parametric studies are performed in terms of return loss and gain of the antenna. All simulations are carried out using HFSS v19.0 and show similar behavior to their experimentally measured counterparts.

Electromagnetic guided mode resonance in dielectric grating affected by transformation of refractive index periodicity

A. Abramov, Y. Yue, V. Rumyantsev — Sun, 12 Feb 2023 00:00:00 +0100

The present work studied effects of transformation of refractive index periodicity on electromagnetic wave propagation through grating waveguides. In lieu of the standard refractive index periodicity, although its unit cell consists of two kinds of materials, we consider few such unit cells as a new supercell, where the material parameters in a standard unit cell are changed. It has been shown how by changing parameters of the periodicity to control the wavelength and intensity of resonant optical mode (guided mode resonance) arising inside grating area. High quality factor calculated for the specific angle of incidence and periodicity parameter. Thus, we demonstrated that transformation of refractive index provides additional tools of controlling the GMR, and that means the sample can be designed more functional in terms of real application.

Electrothermal Analyses of Bandpass NGD RLC-Network Topologies

Sat, 11 Mar 2023 00:00:00 +0100

This paper develops an original study of temperature effect on the unfamiliar bandpass (BP) negative group delay (NGD) lumped passive circuits. The paper presents the first study of electrothermal analysis of electronic circuits classified as BP-NGD topologies. The considered BP-NGD passive cells are mainly constituted by RLC-resonant networks. The equivalence between two basic BP-NGD topologies constituted by RLC-series and RLC-parallel networks is elaborated via the voltage transfer function (VTF) analogy. Then, the theoretical demonstrations are introduced to define the main specifications as the NGD center frequency, NGD value, attenuation and NGD bandwidth. The electrothermal innovative study is developed based on the temperature coefficient resistor (TCR) of elements constituting the BP-NGD circuits. With proofs of concept of RLC-series and RLC-parallel circuits operating with -500 ns NGD value at 13.56 MHz, calculated and simulated results showing are in excellent agreement. The sensitivity analyses of BP-NGD specifications in function of ambient temperature variation from 0°C to 100°C are investigated. The BP-NGD response variations versus frequency and temperature are characterized with thermo-frequency cartographies and discussed.

Generation of OAM Beam with High Azimuthal Symmentry through Planar UCA for Vehicular Communication

Y. Mallikharjuna Reddy, U. V. Ratna Kumari — Thu, 25 May 2023 00:00:00 +0200

In this paper, a uniform circular array (UCA) with circularly polarized (CP) square patches is presented for the generation of orbital angular momentum (OAM) beam with high azimuthal symmetry. The proposed CP UCA is a compact structure with a simple feed network generating OAM beams. The design consists of eight circularly polarized square patch antennas which are geometrically rotated to obtain the required phase distribution. The left hand circularly polarized square patch used as a radiating element in UCA exhibits l = + 1 OAM mode, while the right hand circularly polarized square patch exhibits l = - 1 OAM mode. In addition, the antenna exhibits a single-layer structure, which facilitated the fabrication of the design and reduced the cost as well. The simulated and measured results are reported showing that the antenna exhibits an OAM beam of l = + 1 and l = - 1 modes at 5.85 GHz with high azimuthal symmetry. The mode purity estimation is also reported for the OAM l = + 1 and l = - 1 modes. The gain of the conical shaped OAM beam is almost 11 dBi which makes it quite viable for applications in wireless and vehicular communications.

Broadband Printed Tapered Slot Antenna Fed by CPW Fulfilled with Planar Artificial Magnetic Conductor for X-Band Operation

H. Malekpoor — Tue, 24 Jan 2023 00:00:00 +0100

A low-profile printed slot antenna (PSA) backed by broadband planar artificial magnetic conductor (AMC) is introduced in this study. Firstly, a suggested PSA with the radiating tapered slots excited by coplanar-waveguide (CPW) is used to expand the bandwidth in the measured range of 9-11 GHz (S11≤ -10 dB). Then, the suggested planar AMC surface as the ground plane of the antenna is inserted into the PSA to gain improved radiation efficiency. The realized result from the PSA with the 9×9 planar AMC array exhibits -10 dB measured impedance bandwidth from 6.63 to 13.73 GHz (70%). The suggested PSA with AMC compared to the PSA without AMC exhibits a size reduction of 60%, enhanced bandwidth of 50%, and excellent impedance matching with a minimum value of almost -40 dB. The novel AMC unit cell is realized to operate at 10.14 GHz with an AMC bandwidth of 8-12.35 GHz (43.1%) for X-band operation. Besides, by loading a periodic AMC unit cells into PSA, a high gain of more than 11 dBi with uni-directional radiation patterns is achieved.

On the Computation of the Attenuation Constant by Using the Generalized Telegraphist’s Equations Based Electromagnetic Analysis Method

S. Simion — Sun, 12 Feb 2023 00:00:00 +0100

Numerical results for the attenuation constant obtained by using the generalized telegraphist’s equations (GTEs) based electromagnetic analysis method and comparison with the HFSS (High Frequency Structure Simulator) results are reported. To calculate the attenuation constant with the GTEs method, not only the amplitudes of the voltage modes but also the amplitudes of the current modes must be found. In this paper, it is demonstrated that the relationships reported by other authors for the amplitudes of the current modes are not correct and new ones are proposed. To validate these relationships, the attenuation constants for homogeneous and different partially dielectric-filled rectangular waveguides are computed for the fundamental propagation mode by using the GTEs based analysis method and the results are compared with those obtained with HFSS. It is shown that using the revised relationships for the amplitudes of the current modes, the GTE method can be used to compute accurately the propagation and attenuation constant, but only for propagation modes in which the components of the electric field are not oriented perpendicular to the interface between different dielectrics. This limitation is not due to the proposed current mode relationships, but is due to the GTE method which cannot highlight the electric field discontinuities.

Design of Wide-Band Microstrip Antenna for S-Band Telemetry Applications

Pushpalatha M, Namana N, T. S. Navadagi, Varun D — Sat, 11 Mar 2023 00:00:00 +0100

This paper exemplifies the design of a low profile wide-band microstrip antenna suitable for S-Band telemetry applications. The proposed design explores the concept of wide-band antenna with improved omnidirectional gain and smaller size essentially aiming at low-earth orbit (LEO) satellite telemetry. The proposed partial annular radiating patch design has an operating impedance bandwidth ranging from 2.7 GHz to 3.8 GHz with a percentage bandwidth of 31%. It exhibits vertical polarization with a gain of around 1.434 dBi. The design and simulations are carried out using 3D EM tools and the measurement results for various performance metrics of the antenna are validated with the simulation results.

Microstrip Antenna Array Design for Unmanned Aerial Vehicles Detection Radar

P. Mendes Ruiz, X. Begaud, F. Magne, E. Leder, A. Khy — Sun, 16 Apr 2023 00:00:00 +0200

This work presents the design and realization of four linear arrays of microstrip rectangular patch antennas. This linear array is one of the elements of a passive radar using signals from 4G base stations for UAV detection. The arrays have been validated and operate from 2.62 GHz to 2.69 GHz, with a HPBW of 82° in H-plane and a maximal gain going from 11.1 dB to 12.2 dB in the required bandwidth, with a cosecant squared pattern in the E-plane.

General Approaches to Solving Problems of Analysis and Synthesis of Directional Properties of Antenna Arrays

I. Islamov, E. Humbataliyev — Thu, 27 Oct 2022 00:00:00 +0200

The work carried out the calculation and synthesis of antenna arrays used in radio-electronic complexes on unmanned aerial vehicles. The analytical model is designed to find asymptotic estimates of the polarization components of the electric field of the grating in the far zone of the carrier surface; the results obtained with its use are the initial data for constructing a technique for the numerical solution of a boundary value problem for a grating on a carrier surface in the CST MWS electrodynamic simulation environment. The synthesis of gratings with the maximum achievable coefficient of directional action is carried out with the control of radiation patterns at a given set of angles. A two-mirror antenna system has been calculated. It is shown that with an increase in the number of re-reflections taken into account, the convergence of the result for the calculated characteristics of the antenna is observed. To test the proposed method, the same antenna was calculated using the integral equation method. The comparison showed a high degree of agreement between the results obtained by two different methods. The results of the simulation based on a software algorithm designed to quantify the input matching at the input of a multichannel frequency-scanning antenna array power divider are presented. It was found that when performing wide-angle scanning in a relative frequency band of more than a few percent, the disadvantage of the known method for eliminating the normal effect is a sharp deterioration in matching in the lower and upper frequencies of the operating range. A new method is proposed based on an automated iterative process of optimizing the divider geometry, which makes it possible to obtain an acceptable match over the entire operating frequency band. The feasibility of switching from a serial power divider construction scheme to a series-parallel scheme is analyzed for wide-angle scanning in a relative frequency band of about 5%.