Papers by Keyword: Return Loss

Abstract: This study investigates the fabrication of a cylindrical dielectric resonator antenna (CDRA) using ceramic microwave dielectric composites as a resonator. The composites (1-x) Li₃MgNbO₅-(x) Sr₃V₂O₈ (x=0.25-0.40) have been synthesized via the conventional solid-state reaction method, incorporating 1% B₂O₃ to lower the sintering temperature. The 0.70-0.30 composite exhibited optimal microwave dielectric properties with a dielectric constant (ε_r) of 19.20, a quality factor (Q x f) of 3738 GHz, and a temperature coefficient (τ_f)of -43 ppm/°C. These characteristics render the 0.70-0.30 composite suitable for CDRA applications. The experimentally obtained microwave dielectric parameters were used to simulate the CDRA design using the High-Frequency Structure Simulator design software. A single-feed cylindrical antenna has been fabricated using this composite material as a resonator with a radius × height of 5×6 mm², mounted on an FR4 substrate measuring close to 25×25×1.6 mm³ and Cu strip as a feed line. The simulated and experimentally measured parameters, including S11, voltage standing wave ratio, and radiation pattern, demonstrated excellent agreement, validating the composite's efficacy for antenna design.

Abstract: Lightweight, small, affordable antennas that can sustain good performance over a broad spectrum of frequencies are crucial in the current development of communication systems. The Microstrip patch antennas offer a low gain, narrowband, and efficiency. To get over narrow band's constraints, numerous designs are used. To increase the bandwidth for high data rate transmission, the suggested design has a low profile circular microstrip dual ring patch antenna with slotted partial ground plane. Analyses are done on the performance of single and twin ring patch antennas. Bluetooth, Wi-Fi, WLAN, radar, MIMO, satellite communication, and other applications of wideband are a few. Antennas are simulated using the High Frequency Structure Simulator (HFSS).

Abstract: This paper presented the design of integrated filter antenna for 2.4GHz microwave applications. Open loop resonator bandpass filter is designed to increase the bandwidth of the antenna by producing the range of frequencies that can be accepted by the antenna structure. Direct connection between the filter structure and antenna may cause impedance mismatch and deteriorates the performance of both antenna and filter. Thus, by integrating both filter and antenna into a single module, the overall performance can be improved and increase the efficiency of the system with improved bandwidth. The design used FR4 with dielectric constant of εr = 4.7 with substrate thickness of 1.6mm. It is shown that the simulation result for the proposed integrated filter antenna produce return loss, S₁₁=-20.009dB, gain of radiation pattern is 3.36dB and an increase of bandwidth to approximately 3.74% compare to the single structure antenna.

Abstract: The limitations in the applications of microstrip antenna lead to wastage in the form of space and functionality. In order to overcome the wastage of space and functionality of the microstrip antenna, the new idea is to make one single device of microstrip antenna which has two application at the same time where it can operates as antenna and the function as lighting source is proposed. Light Emitting Diode (LED) has been chosen as the light source since the characteristic and the structure of the LED are suitable for the integration process. Hence, this paper presents an investigation on the characteristic of an H-shaped patch antenna integrated with Light Emitting Diodes (LEDs). The proposed integrated antenna has been designed and simulated by using Computer Simulation Technology (CST) Microwave Studio Software. It has been fabricated and measured to investigate the performance of the antenna in terms of return loss. The results confirms that the antenna can operate at 2.4 GHz and it works well as an illumination.

Abstract: Polycrystalline of (1-x)ZnAl₂O₄ – xSiO₂ compound with compositions of x = 0.00, 0.05, 0.10, 0.15, 0.20 and 0.25 have been prepared using sol-gel method. Structural properties was investigated by atomic force microscopy (AFM) and x-ray diffractometer (XRD). The AFM images analysis showed that the surface roughness of the highest composition had rougher surface compared with other samples. XRD measurement indicated that the crystallite size also increased with average crystallite size around 18 nm with cubic phase had been found. The dielectric permittivity value were measured with frequency range of 1 Hz to 1 MHz. It is showed that the dielectric value decreased as the freqeuncy was applied to the samples. The performance of the patch antenna showed that the antenna resonated at 3.30 GHz and give-13.87 dB with frequency range about 2 – 4 GHz.

Abstract: With the rapid development of the wireless communications, the quality of wireless communications services are increasingly improved, which makes people to pay more attention to efficiency and effectiveness of wireless communication system. Recently, some popular portable devices are those defined by 802.11b, 802.11g and 802.11n protocols, such as Wi-Fi card, Wi-Fi card reader and Wi-Fi hard disk. A dual frequency WLAN antenna used for applications of Wi-Fi portable devices is necessary. The reflection loss (Return Loss) of the antenna is a key parameter, therefore, the antenna return loss and bandwidth must meet the conditions of requirements. We use electromagnetic simulation software to simulate and tune the reflection loss of the antenna to more than 10 dB specification. According to the parameters of simulation results, a dual frequency WLAN antenna used for applications of Wi-Fi portable devices is fabricated.

Abstract: A traveling wave matching (TWM) network is proposed for broadband variable gain amplifier design. The TWM network lessens input return loss and noise figure dependence on VGA’s gain, which is adjusted by biasing of the gain control circuit. A wide band (DC to 12 GHz) VGA with the novel TWM network as input matching is implemented in 2μm InGaP/GaAs HBT (fT of 29.5GHz) technology with die size of 1×2 mm2. As gain control voltage sweeps, the VGA shows a gain tuned from -15 dB to 15 dB and an average noise figure ranging from 8dB to 6.5dB, while S11 (lower than -20dB) and S22 (lower than -10dB) almost unchanged over the operation frequency band.

Abstract: In this paper, an inverted F antenna works in the 5.8GHz frequency band is proposed. On the platform of Ansoft HFSS14 , the antenna’s return loss reaches -51.97dB at the center frequency 5.8GHz and the relative bandwidth is about 22.4％ when the return loss is less than -10dB. Also ,the size of the antenna is only 18mm*15mm. Compared with the existing antenna works in the same frequency band , the inverted F antenna proposed has a lower return loss and smaller physical size. The new designed antenna can be applied to the RFID system of road tolls and container management, which have certain values for application.

Abstract: The electromagnetic simulation software CST was used to analyze the effects of reentry plasma sheath on the GPS navigation antenna. The Impedance and radiation characteristics of antenna were studied on condition that the antenna was coated with uniform and nonuniform electron density distribution plasma sheath respectively. The results show that, the antenna coated with the uniform plasma sheath, the plasma electron density increasing, the antenna operating frequency moves to high-frequency and that the directivity decreases as well; when the antenna was coated with nonuniform plasma, with the higher electron peak density of plasma sheath, besides that the operating frequency also moves to high-frequency, the bandwidth stretches wide and the return loss reduces; the antenna radiation pattern distorts seriously at the electron peak density of 10¹⁸m^-3.

Abstract: A dual-frequency microstrip patch antenna is proposed based on rectangular microstrip patch, with appropriating feed location selection of 50Ω coaxial line, two frequency are respectively applied to 0.8GHz and 0.9GHz. Size of antenna is designed based on the simulation software of HFSS from ANSOFT company, reducing antenna return loss by adjusting size and completing matching between patch and coaxial line, results are analyzed. Simulation results show the design and implementation of microstrip patch antenna have certain reference value with small return loss on 0.8GHz and 0.9GHz.