A compact circularly polarized rectenna with harmonic suppression for wireless power transmission at 5.8 GHz is proposed in this letter. The substrate integrated waveguide structure is adopted for enhanced gain, unidirectional patterns, and surface wave suppression. A rectifier, which consists of a matching network, a diode, and a dc-pass filter, is integrated with the antenna at the back side. The proposed rectenna is fabricated and measured. It features 6.9 dB gain, 0.67 dB axial ratio, and 30 dB return loss. The conversion efficiency is 65.87% with a 700 Ω load. A rectenna array is also built for an increased aperture. It shows 61.49% conversion efficiency with 650 Ω load in measurement. Both the rectenna and array are satisfactory choices for wireless power transfer usage.

A Circularly Polarized Rectenna Array Based on Substrate Integrated Waveguide Structure With Harmonic Suppression

In this paper, a compact ultra-wideband (UWB) multiple-input multiple-output (MIMO) spatial diversity antenna with dual band-notches designed on an FR4 substrate is proposed and experimentally investigated. The antenna consists of two radiating elements fed by two tapered microstrip lines. Two inverted L-shaped slits are used to introduce notches at WLAN (5.15–5.85 GHz) and IEEE INSAT/Super-Extended C-band (6.7–7.1 GHz). An isolation of more than 15 dB is achieved through the whole working band (2.9–10.8 GHz) by introducing a T-shaped decoupling structure on the ground plane. Furthermore, the envelope correlation coefficient (ECC), diversity gain (DG), multiplexing efficiency, TARC, peak gain and radiation patterns of the MIMO antenna are also discussed. The simulated and measured results show that the proposed UWB MIMO antenna is a good candidate for UWB diversity applications.

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A Compact Dual Band-Notched MIMO Diversity Antenna for UWB Wireless Applications

A 2D electromagnetic band gap (EBG) structure is designed on the ground plane of 1×2 rectangular patch antenna array to reduce the mutual coupling between the two elements and enhance the radiation pattern. An isolation of −41 dB has been achieved with the EBG structure relative to −20 dB without the EBG.

Mutual coupling reduction in array elements using EBG structures

This paper presents a high gain antenna for off-grid wireless networks at 915 MHz. The requirements for compact size and high gain antenna are needed in the industrial, scientific and medical (ISM) band for better performance and coverage. Hence, microstrip planar substrate is proposed to overcome the size challenges. The proposed antenna is designed based on rectangular patch with air gap technique. The proposed antenna is optimized using computer simulation technology software (CST) and fabricated on low profile FR-4 substrate. The measured performance agreed well with the simulated one. The reflection of less than -10 dB is obtained with high gain of 6.928 dB at desired frequency. Overall, this antenna can be a good candidate for the off-grid wireless network applications.

https://beei.org/index.php/EEI/article/download/2192/1828

High gain antenna at 915 MHz for off grid wireless networks

Metamaterials exhibit properties in terms of subwavelength operation or phase manipulation, among others, that can be used in a variety of applications in 5G communication systems. The future and current 5G devices demand high efficiency, high data rate, computational capabilities, cost-effectiveness, compact size, and low power consumption. This variation and advancement are possible when the antenna design is revised to operate over wideband, high gain, and multiband and has characteristics of compact size, reconfiguration, absorption, and simple ease of fabrication. The materials loaded with antennas or, in the same cases, without antennas, offer the aforementioned characteristics to bring advancement in order to facilitate users. A number of works on designing metasurfaces capable of improving bandwidth, gain efficiency, and reducing the size and cost of antennas are available in the literature for this purpose. Not only are these applications possible, but the intelligent metasurfaces are also designed to obtain reconfiguration in terms of frequency and polarization. The number of absorbers loaded with metamaterials is also designed to improve the absorption percentage used for radar applications. Thus, in this paper, the general overview of different types of metamaterials and their role in performance enhancement and application in 5G and 6G communication systems is discussed.

/pdf/metamaterials-and-their-application-in-the-performance-3qqzx9fv.pdf

Metamaterials and Their Application in the Performance Enhancement of Reconfigurable Antennas: A Review

For ultrawideband (UWB) applications, a compact multiple-input-multiple-output (MIMO) antenna prototypes are proposed. The first prototype is with a dimension of 40 × 40 mm2. The design consists of seven squares surrounding a center square in which the ground plane is partially implemented. In the second prototype, a compact multiple-input-multiple-output (MIMO) antenna having a size of 36 × 40 mm2 is proposed. To achieve good isolation two planar-monopole (PM) antenna elements are placed perpendicular to each other. On one side of the substrate antenna elements with microstrip-fed is printed. On the other side of the substrate two ground planes are connected via a short ground strip and two inverted U-shape stubs are added to the ground. This arrangement provides good isolation and increase impedance bandwidth. Using High Frequency Structure Simulator Software the results are simulated.

Design of UWB-MIMO antenna for wireless applications

The design and implementation of circularly polarized substrate integrated waveguide (SIW) antenna in X Band is presented in this paper. The substrate integrated waveguides represents the family of substrate integrated circuits which is planar in nature and used for the transmission of electromagnetic energy. In this paper the design techniques for substrate integrated waveguide using slots with the integration of microstrip are presented, which emphasis the broad perspective of the substrate integrated waveguide in circular polarization. The design has simulated in HFSS Software. From the simulation results, it is observed that gain has increased in SIW structure with slots for circular polarization as compared to SIW structure without slots.

The design of high gain substrate integrated waveguide antennas

A broadband electrical metamaterial is proposed in this paper to improve the performance of microstrip antenna. With the help of metamaterial we can improve bandwidth of microstrip antenna as well as miniaturize it. The properties and applications of metamaterial, three half split ring resonator metamaterial and the performance of a system contributing two patch antennas separated by means of a metamaterial based surface at 9.6 GHz for multiple input and multiple output (MIMO) application is explained in this paper. The functioning of two air spaced patch antennas is studied for comparison with that of metamaterial spaced antennas.

http://ieeexplore.ieee.org/iel7/7309521/7322423/07322869.pdf

Efficient method of increase in isolation between patch antennas using metamaterial

RF-MEMS filters will substitute conventional filters as they offer better performance at optimum cost. A bandpass filter is one such filter which is designed using microelectro-mechanical systems (MEMS) technology which have low insertion loss, high quality factors, good temperature stability and have various unique advantages. This paper reports on the implementation of wide bandpass filter using a silicon based integrated passive device technology. The wide bandpass filter is realized on a micromachined (MEMS) silicon substrate. The filter occupies only 1mm × 0.56mm die area and the band pass is achieved using spiral inductors and a gap capacitor. The wide band pass filter is designed using a coplanar wave guide transmission line which is placed on a silicon substrate operating over K-band to W-band. This design is implemented in High Frequency Structural Simulator (HFSS) software. The simulated results shows that the design has the return loss of ™14.7dB and insertion loss of ™1.02dB. A wide bandwidth of 74GHz has been achieved.

Micromachined wide bandpass filter

In this paper, a low pass tri-section stepped impedance filter with wide stop band using I-shaped DGS is presented. A bandwidth of 13 GHz is obtained at stopband. The maximum insertion loss is 0.3 dB and minimum return loss is 60 dB in the pass band. The minimum insertion loss is 47 dB and maximum return loss is 0.3 dB in stop band. Introduction Low pass filters are very important part of communication systems, especially mobile modules, to reject unwanted higher frequencies. They are often followed by a bandpass filter so as to select the specific frequency range from the low frequency provided by the low pass filter. Recently a paper on design of compact low pass filter with wide stopband using tri -section Stepped Impedance Resonator was proposed. The paper discusses about achieving a wideband by changing the impedance ratios of a three sections stepped impedance filter[1]. Another recent paper discusses the design of a tri-section folded SIR filter. It proposes how to reduce the length of a tri-section SIR filter by folding it[2]. Y.Z.Zhu and X.J.Zhang et al., propose the general idea of compact T shaped line filter with ultra wide stopband. The series quarter wavelength line in conventional filters are replaced by open stub T shaped lines, resulting in ultra wide stopband[3]. Wang H.C Yang et al., discuss the design of a compact microstrip low pass filter with ultra wide stopband using SIR. Here semi circular microstrip is used to reduce the size of the filter and open circuited stubs are used to provide selectivity [4]. Kalpana Ramesh Chaturvedi et al., propose a wide stopband 6 pole stepped impedance low pass filter using double equilateral U shaped defected ground structure. It provides dual finite attenuation poles that can be independently controlled by DGS lengths[5]. Govind Singh Takur et al., propose the performance of low pass filter and bandstop filter using DGS[6].J.Y.WU and Y.H.Tseng et al.,propose the design of a compact microstrip lowpass filter using thin slots. Back to back C shaped DGS structures are used to obtain a wide stopband[7]. In this paper, a low pass tri-section stepped impedance filter with wide stopband using I-shaped DGS structure is proposed for GSM 900 for mobile communication. The filter is designed at 1 GHz cutoff. By changing the impedances, a wide stopband is achieved. And by applying the I-shaped DGS further increase in bandwidth is achieved. Tri-section stepped impedance resonator Filters are very important part of communication system. They will select the required frequencies and reject all other frequencies. Low pass filters are of utmost importance because they usually make the first filter in communication modules. They will filter out the lower frequencies up to the designed cutoff and reject all the higher frequencies. They are usually followed by a band-pass filter so as to select the particular frequency ranges among the selected lower frequencies. Stepped impedance filters are created by cascading different impedance sections of microstrip so as to achieve a stepped structure. It is popular because it is very easy to design and is very cheap. In tri-section stepped impedance filter, three different impedance sections are cascaded. The higher impedance section will have a lower area and it therefore acts as an inductor. The lower impedance section will have a higher area and it acts as a capacitor. The intermediate section act as an inductor with respect to the lower impedance section, while it acts as a capacitor with respect to the higher impedance section. So by changing its impedance with respect to the other two will therefore also change the overall inductance and capacitance of the system. Thus by only changing the ratios of the impedances of the sections, one can achieve different characteristics of the filter. So here by changing the impedance ratios, higher bandwidth is tried to obtain. Further increase in bandwidth is obtained by applying I-shaped DGS structure. DGS is nothing but Defected Ground Structure. ie., a slot is created in the ground plane so that the current distribution changes. Changing the current distribution changes the L and C parameters, there by adding new resonance. So the second passband is pushed to higher frequencies, thereby increasing the stopband bandwidth. [Neeraja et al., 2(6): June, 2015] ISSN: 23495197 Impact Factor (PIF): 2.138 INTERNATIONAL JOURNAL OF RESEARCH SCIENCE & MANAGEMENT http: // www.ijrsm.com (C) International Journal of Research Science & Management [59] Design of tri-section stepped impedance resonator This section discusses the methodologies and equations that are to be followed for the design of a stepped impedance filter. The basic structure of a tri-section stepped impedance filter is given in Fig.1. Fig 1. Basic structure of a tri-section stepped impedance filter. Impedance ratios The main parameters under consideration here are the two impedance ratios. These two ratios are K1 and K 2 where

/pdf/low-pass-tri-section-stepped-impedance-filter-with-wide-s9lhlh2271.pdf

Usha Kiran K

Papers

Design of UWB-MIMO antenna for wireless applications

The design of high gain substrate integrated waveguide antennas

Efficient method of increase in isolation between patch antennas using metamaterial

Micromachined wide bandpass filter

Low pass tri-section stepped impedance filter with wide stopband using dgs