Duong Bach Gia
VNU University of Engineering and Technology

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Design and fabrication of A Ku-band low noise amplifier using FR-4 substrate Linh Ta Phuong; Bernard Journet; Duong Bach Gia
TELKOMNIKA (Telecommunication Computing Electronics and Control) Vol 18, No 1: February 2020
Publisher : Universitas Ahmad Dahlan

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12928/telkomnika.v18i1.13196

Abstract

The low noise amplifier (LNA) plays an important role in many communication systems, especially at the receiver’s front-ends. In modern RF designs, The LNA is usually fabricated on a microstrip printed circuit board (PCB) due to its simplicity and ability of integrating flexibly with other components in a receiving circuitry unit. At frequencies lower than 6 GHz, the most prevalent substrate material for a microstrip LNA is FR-4 while at higher frequencies of over 10 GHz, it is challenging to design the LNA using this material without causing considerable losses to the RF signal. There are many works related to design microstrip LNA at high frequencies, however, the dielectric substrates used in most of them were high-cost materials for low dielectric loss. This paper introduces an LNA topology using the common, low-cost FR-4 substrate which can be operated in Ku-band for applications such as small satellites’ receivers, with the expected noise figure of lower than 1 dB, gain of around 10 dB and the return loss of around -10 dB. The stepped impedance matching technique has been used for transmission line optimization. The simulated and measured results are presented.
Research, design and fabrication of a microwave active filter for nanosatellite’s receiver front-ends at s-band Linh Ta Phuong; Bernard Journet; Duong Bach Gia
TELKOMNIKA (Telecommunication Computing Electronics and Control) Vol 17, No 1: February 2019
Publisher : Universitas Ahmad Dahlan

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12928/telkomnika.v17i1.10079

Abstract

In satellite technology, the communication between space segment and ground segment plays a vital role in the success of the mission. This paper is targeted at study, design and fabrication of a microwave active filter for the receiver front-ends using coupled line filter structure, which can be applied to the nanosatellite’s communication subsystem. The whole active filter module is a combination of a microstrip bandpass filter and a preceding two-stage wideband low noise amplifier using FET devices. The proposed module operates in the frequency range of 2-2.4 GHz, which can be divided to 10 frequency slots of about 40 MHz for each. These frequency slots will be used for the S-band multi-frequency receiving function of the ground station, as well as the nanosatellite. The simulated and measured results of this active filter configuration are presented.
A design of wideband high-power 3-dB quadrature coupler using defected ground structure for status data transmitting system The Anh Nguyen Dinh; Long Hoang Duc; Duong Bach Gia; Dragos Dancila
Bulletin of Electrical Engineering and Informatics Vol 9, No 1: February 2020
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (644.182 KB) | DOI: 10.11591/eei.v9i1.1699

Abstract

The paper presents a wideband 3-dB quadrature coupler designed for operation at 2 GHz. The presented coupler is based on a broadside-coupled suspended structure in combination with a proposed defected ground structure (DGS) allowing for high power, wide-band and improved harmonic suppression performance. The experimental results show 0.2 dB of insertion loss, return loss of better than 18 dB and isolation of better than 25 dB in the frequency range from 1.74 to 2.67 GHz. The proposed coupler is able to be integrated in the status data transmitting system, which is suitable for vessel monitoring. The fundamental characteristics of the implemented coupler have been measured and verified.