Lee Yeng Seng

Effect of different substrate materials on a wearable textile monopole antenna

In this paper the investigation of the effect using different substrate materials on a textile monopole antenna is discussed. This textile monopole antenna is designed to be used for Body-Centric Wireless Communications (BCWC) at 2.45 GHz. Three types of non-conductive materials were selected: felt, fleece and foam. The textile monopole was benchmarked against a conventional FR-4 monopole antenna. The results demonstrated a good agreement between simulated return loss of all three substrates used for textile monopole antenna and conventional monopole antenna. The felt-based textile monopole antenna offered higher return loss compared to other substrates and conventional monopole antenna. Moreover, the substrate materials gained bandwidths of up to 1000 MHz in free space where fleece fabric produced broader bandwidth compared to other substrates. The simulated gain characteristics for all three types of substrates agreed reasonably well with conventional monopole antenna.

Design of Ground Penetrating Radar antenna for buried object detection

In this paper, the design of planar antenna for use in Ground Penetrating Radar (GPR) for buried object detection is presented. The proposed antenna offers wide operational bandwidth within 500 MHz to 2 GHz frequency band. This property makes the antenna suitable for the application of GPR for buried object detection. Taconic TLY-5 is used as the substrate with dielectric constant of 2.2, tangent loss of 0.0009 and thickness of 1.57 mm. The proposed antenna has simple structure and fully planar, therefore it is easy to integrate with other planar devices. To obtain a directional radiation pattern, the antenna is placed inside an open metallic shielded box. In turn, the gain of the antenna is also increased using this approach. The results in term of reflection coefficient, gain, radiation pattern of the antenna are discussed in this paper.

Frequency selective surface for enhance WLAN applications

This paper proposes the deployment of frequency selective surface (FSS) structure in WLAN device. Objectives to create a band pass square-loop filter FSS in WLAN device to increase the received signal strength of WLAN signal 2.4GHz. FSS works to enhance the 2.4 GHz signal and attenuate the rest signal other than 2.4 GHz. The WLAN signals increasing more than 50 % when pass through the FSS structure.

Performance of Sugarcane Bagasse and Rubber Tire Dust Microwave Absorber in Ku Band Frequency

The electromagnetic interference (EMI) absorbing materials in various microwave frequency were required most now due to increasing demand of electromagnetic compatibility (EMC) for electronic devices with various electromagnetic environments. So, absorber materials are needed in RF/Microwave to eliminate and absorb electromagnetic energy. Absorbers can be used to create a free space environment in anechoic chamber. This work describes the performances which are the reflection loss and absorption for composite of sugarcane bagasse mixed with rubber tire dust microwave absorber in Ku Band frequency (12.4–18 GHz). The parameters such as dielectric properties, reflection coefficient (S11) and transmission coefficient (S21) were investigated. The main objectives of this research are to design and develop a microwave absorber with new green materials which are sugarcane bagasse and other waste material such as rubber tire dust. These agricultural wastes can help save the nature and the fabrication cost of microwave absorber can be reduced. Based on the result, it proved that the sugarcane bagasse-rubber tire dust can be a good alternative material to be used as microwave absorber and can operate in frequency range between 12.4 and 18 GHz.

Determination of Dielectric Properties of Bismuth Titanate (BiT) Ceramic Material for WiMAX/WLAN Antenna

The utilization of Bismuth Titanate (BiT) as a ceramic material on an antenna has been investigated. The BiT ceramic material is of interest for a range of Wireless Local Area Network (WLAN) IEEE 802.11 b/g and Worldwide Interoperability for Microwave Access (WiMAX) IEEE 802.16 application, which covers the range of 2.3 GHz to 2.5 GHz. The BiT ceramic material had been tested to own a high dielectric constant of εr= 15 that is able to miniaturize an antenna. There is a high demand nowadays on the miniature antenna for smaller devices. An experimental prototype at WiMAX/WLAN range was built and measured on its dielectric properties, especially the dielectric constant and dielectric loss of the prototype material.

Switchable beam antenna

This paper introduces the Switchable Beam antenna which has the ability to shift the direction of the Wi-Fi signal to any specific direction depending on the availability of user. The designs of eight radiating patches are installed in between aluminum plates which are fixed by the edges of the other aluminum plate. This is to represent eight angles where the antenna will radiate. By using switches, the beam of the radiating energy can be adjusted to be directed to a specific area. This antenna is operational at 5.8 GHz which is Wi-Fi frequency. The antenna generated a gain of 4.07 dB while the directivity is 9.986 dBi. Apart from Wi-Fi applications, the design can be customized in different frequency to support different application such as GSM.

The Design of Ultra-High Frequency (UHF) Radio Frequency Identification (RFID) Reader Antenna

This paper presents the design of ultra-high frequency (UHF) radio frequency identification (RFID) reader antenna using low dielectric constant of microwave substrate. An RFID reader antenna emits electromagnetic signals to the microchip in the tag, and the microchip will be energized by modulating the wave and returns to the reader antenna. The process of wave emitting is known as backscattering due to the presence of tag been detected by the reader. High-dielectric constant substrate, for example flame-retardant-4 (FR4) which is commonly used for microstrip patch antenna, is high in dielectric constant and dielectric loss. Thus, this will lead to low gain and directivity properties of the antenna. To overcome this matter, low-dielectric constant substrate which is Taconic TLY-5 was proposed to be utilized for microstrip patch antenna design. The TLY-5 microstrip substrate thickness used is 1.6 mm, dielectric constant of 2.2, and loss tangent of 0.019. A high-conductivity metal which is typically a conductive copper is been used for the two layers of dielectric substrate, the top radiating patch layer and bottom ground layer where the copper thickness is 0.035 mm. Microstrip feed line is used for this UHF RFID reader antenna. The width of the feed line was tuned to obtain impedance matching of 50 Ω. The proposed antenna which is fork-shaped patch antenna was simulated using Computer Simulation Technology (CST) and Microwave Studio software at resonant frequency of 910 MHz with the outcome results of 7.985 dB gain and −11.11 dB return loss. Nevertheless, the typical value obtained for VSWR is less than 2.

Side lobe suppression of Vivaldi antenna using shorting pin structure

This paper was executed in order to design side lobe suppression of Vivaldi antenna using shorting pin structure at S-band frequency. Nowadays, Vivaldi antenna has been used to satellite communications, remote sensing and radio telescope. There are a variety of designs such as tapered slot Vivaldi antenna, antipodal Vivaldi antenna and balanced antipodal Vivaldi antenna. Tapered slot Vivaldi antenna has been selected to design the project. The design of the antenna is start with patch antenna by using basis of transmission line model (TLM) formula to calculate the length and width of the patch. It is shaped into Vivaldi antenna. For the final design, the shorting pin structure will connect the patch on top side and the ground plane to absorb the unbalanced current. The shorting pin will reduce the side lobe. The antenna was simulated by using CST Microwave Studio. Based on the simulation results, the Vivaldi antenna shows a good performance as the return loss less than - 10 dB, voltage standing wave ratio, gain, directivity and radiation pattern was obtained the desired result as for a resonant frequency of 3 GHz. The radiation pattern of Vivaldi antenna with shorting pin structure reducing as compared with the design without shorting pin structure. The final antenna design shows that it has a few main lobe magnitudes where the antenna can focus and direct the energy for transmission or receiving of the energy signal.

On the Miniaturization High Permittivity DRA with Array Patches

The miniaturization on planar printed-circuit antennas by loading the ceramic material of high permittivity material bismuth titanate has been experimentally demonstrate on the micro strip patch antenna. Due to its very small size and radiation performance, it is compatible for packaging constraints and can be easily integrated in a big variety of portable devices. The results show that the size reduction is achieved with the gain of the ceramic material antenna comparable with that of conventional micro strip antenna. In this paper, the miniaturized antenna array technology with high permittivity ceramic material, bismuth titanate array antenna is described, along with comparison computer simulation results with conventional micro strip patch antenna.