Abstract This work proposes the integration of a monopole antenna with a frequency selective surface (FSS) with double square loop geometry, which operates in the ISM (2.4 - 2.4835 GHz) and IEEE 802.11 WLAN (5.15-5.725 GHz) bands. The FSS was developed to be integrated into a microstrip monopole antenna, aiming to improve some of its radiative features, such as gain, directivity, and front-to-back ratio (FBR). We show that the double square loop FSS operates in bands from 1.91 to 3 GHz and from 4.64 to 6.56 GHz, fully covering the bands of interest. A prototype of the proposed structure was assembled and both the numerical simulation and the experimental results show that the antenna integrated with FSS presents significant improvements in all parameters, compared to the antenna without FSS. Because of the interest frequency ranges the proposed structure can be applied in non-invasive biomedical applications. (FSS geometry 2.4 24 2 4 (2. 24835 4835 2.483 80211 802 11 802.1 5.155.725 5155725 5.15 5.725 5 15 725 (5.15-5.72 features gain directivity fronttoback front back FBR. FBR . (FBR) 191 1 91 1.9 464 64 4.6 656 6 56 6.5 parameters noninvasive non invasive applications 2. (2 2483 483 2.48 8021 80 802. 155 5.155.72 515572 515 5.1 5725 5.72 72 (5.15-5.7 (FBR 19 9 1. 46 4. 65 6. ( 248 48 8 5.155.7 51557 51 5. 572 5.7 7 (5.15-5. 5.155. 5155 57 (5.15-5 5.155 (5.15- (5.15 (5.1 (5. (5

Abstract In this article, the authors propose changes to a microwave system for measuring the relative humidity of hollow concrete blocks presented in the literature, aiming to improve the system’s sensitivity. The operating frequency range was changed from 2.5 GHz to 5.8 GHz. This reduced the dimensions of the antenna arrays used in the system. Five block samples were used in this work. The frequency selective surface (FSS) used as a sensor has been modified, from a double circular ring to a square loop, which presents a single-band frequency response. The results obtained in this work showed a high correlation between the frequency variation and the relative humidity level. First, second, and third-order functions were compared to see which would better relate resonance frequency to relative humidity. The second-order function presented the best results, considering the Mean Absolute Percentage Error (MAPE), the Mean Square Error (RMS), and the coefficient of determination. We performed a sensor sensitivity analysis showing that the new proposed system is more sensitive than others presented in the literature. article literature systems s 25 2 5 2. 58 8 5. FSS (FSS modified loop singleband single band response level First second thirdorder third order secondorder MAPE, MAPE , (MAPE) RMS, RMS (RMS) determination (MAPE (RMS

Abstract In this paper, a planar near-zero refractive index material (NZRIM) consisting of an outer loop with four symmetrical quarter-rings is proposed. The quarter-rings are connected to the outer loop by two symmetrical microstrip lines on the opposite side. The backside of the substrate has mutually central split microstrip lines. By loading adjustable capacitor between the split in the center of the backside of the substrate, the resonance frequencies of the proposed NZRIM can be controlled and thus the epsilon-near-zero (ENZ) frequency bands change correspondingly. According to the specific frequency bands of its metamaterial characteristics, the proposed NZRIM can be mounted above the surface of different antennas with different operation bands for 5G applications. Results show that the proposed NZRIM can enhance the forward radiation gain of antennas.

Abstract In this paper, a microstrip patch antenna (MPA) design was developed to verify the performance of a metamaterial cell array (MTM) Capacitive Loaded Loop (CLL) immersed in the substrate. The metamaterial was obtained from metal laminates designed inside a dielectric material, with dimensions carefully calculated to have the effective negative permittivity and permeability, consequently the negative refractive index, in a certain frequency range. In this case, the geometric control of the unit cell parameters allowed its organization in a periodic arrangement to be immersed in the MPA substrate. Simulated and experimental results were obtained and compared for some parameters of the antenna, which showed a good relationship between MTM and MPA performance.

Abstract This manuscript proposes a Filtenna operating in the frequency range of 5.15-5.35 GHz for possible application in wireless local area network (WLAN). Initially, a monopole antenna consisting of a square loop radiating patch is designed at 5.2 GHz and is integrated into a bandpass filter (BPF) with centre frequency of 5.2 GHz. Within the proposed frequency band of operation, the filtenna exhibits omni-directional radiation pattern, good selectivity and low reflection loss. Also, the VSWR observed is less than 2 and peak antenna gain is approximately 2.5 dBi within the frequency range. A consistency is obtained between the simulation and the experiment.

Ondas de radio provenientes del planeta Júpiter son fenómenos electromagnéticos generados por emisión de sincrotrón, debidos a la interacción del campo magnético Joviano con partículas cargadas producidas por su luna Ío. Estas ondas de radio interactúan con la ionósfera, afectando las radio-comunicaciones terrestres. En el Observatorio Astronómico de la Universidad Tecnológica de Pereira (OAUTP) el grupo de investigación en Astroingeniería Alfa-Orión desarrolló una antena tipo Loop Magnética diseñada para resonar a 20.1 MHz, la cual fue acoplada con el receptor y el software del proyecto de la NASA Radio Jove. Esto permitió la observación de las fuentes de radio A, B, C, IoA, IoB y IoC desde Júpiter, permitiendo la construcción de una base de datos para el estudio de la actividad Joviana en ondas de Radio.

Radio waves coming from the planet Jupiter are electromagnetic phenomena generated by synchrotron emission mechanism, due to the interaction of Jovian magnetic field with charged particles produced by the satellite Io. These radio waves fall directly upon the ionosphere affecting earth's radio communications. At the Astronomical Observatory of the University of Technology of Pereira (OAUTP) the research group in Astro-engineering Alfa Orion, developed a magnetic loop antenna designed to resonate at 20.1 MHz, which coupled with the receptor and the software from NASA's Radio Jove project enabled the observation of radio sources A, B, C, IoA, IoB and IoC from Jupiter, allowing the construction of a database for the study of the Jovian activity in radio waves.

In this paper, single and dual band EBG structures for wider bandwidth are proposed. In each of the discussed EBGs, a metallic patch of regular geometry is chosen for the unit element. The patch is further modified by cutting slots to get extra inductance and capacitance which results into lower cut-off frequency and larger bandwidth. The proposed EBG structures are compared with the standard mushroom type EBG with respect to surface wave attenuation. The -20 dB cut-off frequencies and bandwidths of the various EBGs are compared. The effect of unit element size, gap between unit elements and via diameter on the transmission response is presented. Among the discussed EBGs, the swastika type structure is compact, single band and has wider bandwidth. The square patch with a single disconnected loop type slot EBG and the Fractal EBG are dual band. While square patch is more compact, the fractal EBG has wider bandwidth. All the EBGs can be useful in the design of antenna and other microwave circuits.