Metamaterial-Inspired Electrically Compact Triangular Antennas Loaded with CSRR

SummaryThis paper presents two different configurations of ±45° dual‐wideband dual‐polarized (DWDP) antennas. The antenna comprises eight end‐loaded broadband dipoles grouped into two sets based on the bands of operation. The high‐frequency dipoles are strategically placed within the low‐frequency ones to form the elementary unit. Further optimization has been performed on the elementary unit in terms of the radiator placement to suppress sidelobe levels for array formation. Both configurations are meticulously fabricated using an all‐metal structure, demonstrating durability and the simplicity of fabrication. The antenna designs achieve ±45° polarization, high gain, satisfactory cross‐polarization discrimination (XPD), and wide impedance bandwidth covering 0.67–1.04 GHz and 1.54–3 GHz bands. Despite the nested configuration, mutual coupling is well within acceptable limits. Formation of the array based on the optimum elementary unit has been investigated by simulation, revealing reasonable gain enhancement and low sidelobe levels across all bands. This comprehensive approach yields a robust, high‐performing antenna configuration suitable for indoor distributed antenna system (IDAS) applications.

A survey of the recent studies and findings on miniaturized, compact, low profile microstrip patch antennas (MSA) using metamaterials (MTMs) is presented. The MTM based theoretical and practical design techniques, and issues for RF and wireless communication systems have been investigated. Theory and principles of these electromagnetic artificial materials have been discussed in terms of physical and electrical characteristic parameters like quality factor, bandwidth, efficiency, VSWR, polarization, size, shape, permittivity, permeability and frequency response that are necessary for optimally designing the antennas. Microstrip transmission lines using left handed (LH-TL) MTMs are being used as feed for MSA to avoid the mismatching and hence improving the overall antenna system efficiency. In this study paper, the LHTL design considerations have been investigated. Finally, further researches on development needs are identified for these MTM antennas to cover the dual and tri-bands for wireless applications. Theoretical analysis methodology and design approaches of rectangular and circular MSA are presented that helps to optimize the performance of these antennas in real time. The effects of a radome structure on the radiation pattern, antenna gain and bandwidth have been investigated and methods to further improve the MTM antennas are spotlighted. An exhaustive list of references has been provided to encourage and facilitate the MTM and MSA research aspirants.

The paper studies synthesizing capabilities of a flat-topped radiation pattern when using the expansion of the target radiation pattern into a series in terms of odd Mathieu functions. As parameters for comparing the target and synthesized radiation patterns, we used a main-lobe width at a level of -1 dB and an irregularity of the top of the main-lobe of the radiation pattern. The sector-shaped radiation pattern has been synthesized for linear radiators of various lengths. The convergence of the coefficients of the Mathieu series in the synthesis of the sector-shaped radiation pattern has been estimated. It is shown that the use of piecewise-linear approximation of the target radiation pattern in the synthesis using a series expansion into odd Mathieu functions allows us to improve the quality of the radiation pattern formed.The task that involved finding the amplitude-phase distribution for a linear emitter with a length of 3λ, 4λ and 5λ (λ is operation wavelength) for a target radiation pattern was solved. The target amplitude distribution has the following electrical characteristics: the main-lobe width is 37.5° at a level of -1 dB and the side lobe level (SLL) is -20 dB. The synthesis procedure was performed for two cases. In the first case, the target radiation pattern is represented by a piecewise constant function with a given width. In the second case, the target pattern was specified using piecewise linear approximation of the top and slopes of the main lobe.Comparison of the radiation patterns obtained shows that in the first case, the main-lobe width of the radiation pattern at a level of -1 dB is 34°, the SLL varies from -15.6 to -17 dB, and the irregularity of the main-lobe top of the radiation pattern lies within 0.9 ... 1.2 dB. In the second case, the main-lobe width of the antenna radiation pattern at a level of -1 dB is 36.5°, the SLL is -17.5 dB, and the irregularity of the main-lobe top is 0.4 dB at most. When used, the considered under consideration enables us to obtain both the synthesized patterns for linear radiators of various lengths, and the corresponding amplitude-phase distributions and coefficients of the Mathieu series. An estimate of the convergence of the Mathieu series shows that the use of linear approximation of the target radiation pattern in some cases allows up to 2.7-fold increase in acceleration of the convergence of the Mathieu series. The accuracy of reproducing the sector-shaped pattern by the synthesis method using the expansion into odd Mathieu functions gives good results when synthesizing the amplitude-phase distribution for the linear radiators with an electric length of 5λ or more.

To bring fifth generation (5G) mobile communication capabilities to indoor users, small cells and distributed antenna systems are two promising technologies being considered. This paper investigates and compares the performance of indoor deployed small cell base station (SBS) and indoor distributed antenna systems (DAS) in an isolated multi-storey building. Each floor of the building is equipped with either an indoor SBS or an indoor DAS where geographically distributed remote radio heads (RRHs) are connected to a central unit (CU), and frequency reuse is employed among floors. Signal propagation characteristics within multi-storey buildings and the impact of inter floor interference on performance is analysed and compared for both systems. The effect of different reuse distances, pathloss exponents, penetration loss and co-channel interference on achievable rate is analysed over a wide range of potential mobile equipment (ME) locations

This paper presents a method for sidelobe level (SLL) reduction, return loss improvement, and bandwidth enhancement in notch-loaded TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">30</sub> mode rectangular patch antennas. In this method, a fractal-slot is introduced in the center of notch-loaded patch to remove the unwanted out-of-phase current regions. It is shown that a combination of the fractal-slot and notch loading technique can achieve significant improvement in SLL, return loss, and bandwidth of notch-loaded TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">30</sub> mode without compromising gain or symmetry of radiation patterns. Moreover, the method also gives an additional degree of freedom to improve the impedance matching without changing the feed location. A prototype of the antenna is fabricated to verify the proposed method. The proposed antenna shows a measured gain of 13 dBi with a low SLL of −16 dB. Furthermore, it shows symmetrical patterns in both planes with cross-polarization (X-pol) levels of less than 35 dB. An under-sampled <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$4\times 4$ </tex-math></inline-formula> array of the proposed antenna is also presented by utilizing its low SLL property to simplify the complexity of feed networks in high gain array antennas. The array offers the same directivity and SLL as that of an <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$8\times 8$ </tex-math></inline-formula> array of fundamental mode rectangular patch elements in the same area.

The aim of this paper is to investigate applicability and the effectiveness of the metamaterial-based antennas for a 5.8-GHz Doppler radar. Thus, a double negative index metamaterial structure is designed as a transmitter antenna and a near-zero index medium is integrated with a patch antenna for the receiver. Significant improvements in bandwidth for the transmitter, slight improvements in gain and in directivity for the receiver, and typically size reduction for both antennas are obtained. It is shown that return loss, radiation pattern, and gain measurement results of the newly designed antennas agree well with the simulations for a desired frequency band. The last part of the study is devoted to express the adaptation of the antennas for a low-power radar system whose aim is to reconstruct the velocity of the human, indoor as well as behind the wall, from the shift in the received frequency. The accuracy of the velocity measurements and field test results of the radar with the metamaterial antennas are reported.

This paper aims to describe the performance of the palm tree Coplanar Vivaldi Antenna Array (CVA) that was simulated from 0.25-6.25 GHz in terms of return loss and radiation pattern. Palm Tree Coplanar Vivaldi Antenna is available in four different configurations: single-element, two-element array, four-element array, and an eight-element array. We create a feeding network and radiator patch for two, four, and eight-array antennas. The simulation results demonstrate that the single-element antenna has the best return loss performance and can cover all frequency work from 0.25-6.25 GHz. In contrast, the antenna array can only cover multiband frequency. At 3 GHz, a single-element antenna has a directivity of 8.77 dBi, a sidelobe level of -2.2 dB, and a beamwidth of 63.70. In contrast, an antenna array of 8 elements has a directivity of 15.5 dBi, a sidelobe level of -12.6 dB, and a beamwidth of 80. Using the same substrate size, by configuring the Vivaldi Coplanar antenna to be an array at a frequency of 3 GHz, the 1×8 array antenna has a 6.73dBi improvement in directivity, a 10.4 dB boost in side lobe level, and a 55.70 enhanced in beamwidth performance compared to a single element. According to the simulation findings, the radiation pattern performance of the. Palm Tree CVA is greater than a single element in the same substrate size. Good directivity, SLL, and beamwidth performance make the proposed Palm Tree CVA array suitable for integration in telecommunication, radar, or cognitive radio applications.

This paper presents the design and simulation of a compact Planar Inverted-F Antenna (PIFA), suitable for ultra wide band wireless communication. The proposed antenna is designed to have both, a slotted radiator and also a slotted ground plane. The substrate used is FR4 substrate, with a dielectric constant of 4.4 and the volume of the antenna is designed as 40 × 40 × 3.5 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> . Using the High Frequency Structure Simulator (HFSS) simulator, and analyzing the different antenna parameters such as the return loss, radiation pattern, VSWR, gain etc., the proposed antenna is successfully simulated for an operating frequency range from 4.4 GHz to 15 GHz, having a bandwidth of 10.6 GHz. Because of its compact size, low profile and broad bandwidth, the proposed UWB PIFA stands as a suitable candidate for many types of wireless communications.

In the present study, the suitability of Ni-Co spinel ferrites as dielectric substrate for microstrip patch antenna has been reconnoitered in X-band frequency range. The scrutinized spinel ferrites with chemical composition Ni 1 . xCoxFe 2 O 4 (x=0.00,0.30,0.60,0.90) were synthesized using Pechini's sol gel method. For the present study, Ansoft Designer SV2 was used to design and analyze the microstrip patch antenna. Simulation of antenna was done at resonant frequency of 10.02 GHz, which makes this research to find application in military and surveillance. Firstly, the antenna dimensions were calculated using resonant frequency and electromagnetic properties of the compositions. The antenna output parameters such as return loss, bandwidth, VSWR (Voltage Standing Wave Ratio), Smith Chart and radiation pattern were subsequently analyzed by the simulation Based on the analysis, Ni-Co ferrite Ni 0.l Co 0.9 Fe 2 O 4 has come out to be the best alternative out of the studied compositions for its possible usage as efficient dielectric substrate in microstrip patch antenna in 8.2 – 12.4 GHz frequency range.

In this paper, an antenna with 8 GHz (7–15 GHz) bandwidth is designed, simulated, fabricated, and measured. Commonly, for the effective use of electromagnetic sources, mode converters are used to transform donut-shaped patterns to directive patterns. This paper introduces a novel antenna called the pattern director antenna (PDA) that solves most problems associated with the azimuthally symmetric output modes of high-power microwave sources. The PDA accepts directly (without the need for mode conversion) an azimuthally symmetric generated mode of an electromagnetic source and converts it to radiate a directive pattern. For the proof of concept and validation of the design by simulations, the 3D printing technology [using polylactic acid (PLA)] is used to fabricate the PDA and measure its radiation patterns and return loss. The selected material is cheap and also environmentally friendly. The antenna was coated with aluminum to become a conductor. The gain is from 16.8 to 21.8 dB in the frequency range. The S11, main lobe deviation (MLD), and sidelobe level (SLL) are less than −15 dB, 2°, and −7 dB, in all frequency range, respectively. The simulation results are in good agreement with the measurement.

In this paper, a new method for designing an active dual-band dipole antenna is proposed. The operating frequencies of the proposed antenna are 150 and 450 MHz that are usually used in military applications. Using a series stub is the main idea in the proposed dual-band antenna, where it makes an independent resonance frequency higher than the main resonance frequency of a conventional dipole. To make appropriate matching impedance in the two frequency bands, the technique of creating an internal coaxial cable is used. Furthermore, to improve the antenna gain, an amplifier is in series part connected to the proposed dipole antenna. The simulated and measured results of the return loss, radiation patterns and antenna gain show that this antenna has a good operation in both resonance frequencies.

This paper presents a compact dual band metamaterial antenna for WiMAX applications. The reported antenna was based on using a metamaterial modified left handed transmission line unit cell. The designed antenna was introduced to operate with the WiMAX lower 2.4 GHz band and upper 5.8 GHz band. The designed antenna has the advantages of its compact size (only 2 × 3) cm2. Compared to the conventional patch length, the designed patch radiator is only 25% at 2.4 GHz and 60% 5.8 GHz. The antenna designed was discussed theoretically and its performance was verified using the electromagnetic full wave simulations. The results confirm that the antenna can introduce the dual bands operation with return loss better than 15 dB at each operating band. Moreover, the radiation pattern is almost omnidirectional at the two bands.

In the wireless broadband network, most traffic are generated from indoor users. Meanwhile the indoor coverage is identified as the major bottleneck especially in dense urban environment with high-rising buildings. In this paper, the TD-LTE network downlink performance of indoor is studied with various network deployment options, including outdoor Macro cell, outdoor Micro cell, indoor distributed antenna system (DAS), indoor Femto cell, and their combinations in a realistic large-scale dense urban scenario. Since a DAS cell consists of several or even tens of access points (AP), the computation load is too high to be accepted when calculating the received signal power and the interference power by traditional widely-used methodology. Thus a new DAS model is proposed to decrease the computation complexity to a reasonable level in the simulation. To have more accurate channel modeling, the real three-dimensional (3D) city map of the investigated area is employed. A 3D ray-tracing tool is used to estimate the large scale propagation occurring between outdoor sites and buildings. The traffic offloading features of Micro, DAS, and Femto cell are evaluated through system simulations.

Complex materials with artificial structures known as metamaterials (MTM) have unique properties that draw several scientists to use them in a variety of research fields. In addition, MTM can go beyond some of the restrictions placed on tools used in technical practise while improving the characteristics of microwaves. The Internet of Things (IoT) application calls for the construction of zero-index Split Ring Resonator (SRR) MTM element superstrates with an ultra-wideband antenna. Keep in mind that the MTM simulates behaviour that is not found in nature, namely the zero-reflection phase (dB) on the resonance frequency. For this project, an antenna with an SRR MTM unit cell operating at 2.70 GHz is built. The SRR has four inductance-related loops (r1, r2, r3, and r4), and gaps (slots) are added to the ring to produce the capacitance effect. Parametric research has been done for the SSR in the interim to identify the best design with zero indexes, permittivity and permeability at the desired frequency. The MTM unit cells array design's 7 x 4 and 10 x 5 dimensions achieved a dB of 0° at the 2.70 GHz frequency range. A 7 x 4 MTM unit cell makes up the first design, MTM Antenna Design 1, which at 2.70 GHz recorded a gain of 5.70 dB and a return loss (S11) of -20.007 dB. The return loss (S11) at a frequency of 2.70 GHz was -19.734 dB in the second design, an MTM antenna consisting of 10 x 5 MTM unit cells, which recorded a gain of 5.66 dB.

Radio Frequency Identification technology aims at identifying and tracking objects labeled with tags. To achieve this goal, the need for antennas with certain characteristics and specifications becomes of great importance. In this research work, a proposed compact broadband meander antenna for Radio Frequency Identification Applications is presented. In the proposed model of the antenna, the inductive strips are bent to generate capacitive effects between them. To achieve an acceptable impedance matching at a frequency of 876MHz between the antenna and the receiving microchip of model “NXP UCODE G2XL”, shorting lines created along the antenna structure together with a T-shaped matching circuit are used. This proposed design of the antenna results in a compact size antenna (75×25×1.6mm3) with a resonance frequency that lies in theEuropean band of 867MHz, and it has an input impedance of Z = 16 - j156 Ω. The antenna is made from copper strip with a thickness of 35 μm and fabricated on an FR4 epoxy substrate with a thickness of 1.6 mm. This paper presents the proposed antenna simulation results performed in various situations and conditions. The antenna performance is investigated in terms of various aspects such as gain, radiation pattern, return loss, and input impedance.