Kamarulzaman Mat

Design of ftth monitoring system based on zigbee wireless sensor network

As part of its ongoing efforts to support the nations call for higher broadband speeds, Telekom Malaysia Berhad (TM) started to launch the new fibre-to-the-home (FTTH) broadband access solution by the second half of 2008, which will offer users the preliminary step towards the digital home experience. Fault protection became important issues in order to present an efficient FTTH network and simultaneously and provide continuous services to the end user without being interrupted by any failure in fiber lines. The failure at optical lines will give two negative impacts. First, the fiber cut will cause optical leakage that is able to damage our eyes. Second, an interruption will occur during the distribution of multimedia service to customers for a long period of time. In the traditional method, when there is a breakdown in FTTH lines, the engineer must go to the failure location to check the optical cable using an optical time-domain reflect meter (OTDR). The disadvantage of this conventional method is that the engineer must leave the Central Office to inject a laser from customer location. It will cause inconvenience, service disruption and waste valuable time for both parties. We proposed optical sensor integrated with wireless sensor network to determine the condition of all optical lines in FTTH network. This system is capable to monitor the condition of all optical lines and make automatic switching for restoration purpose. Every sensor will be put in every line and can communicate each others to ensure the operation of network. One receiver is located in Central Office (CO) to allow engineer to monitor and control all optical lines.

A Compact Ultrawideband Antenna Based on Hexagonal Split-Ring Resonator for pH Sensor Application

A compact ultrawideband (UWB) antenna based on a hexagonal split-ring resonator (HSRR) is presented in this paper for sensing the pH factor. The modified HSRR is a new concept regarding the conventional square split-ring resonator (SSRR). Two HSRRs are interconnected with a strip line and a split in one HSRR is introduced to increase the electrical length and coupling effect. The presented UWB antenna consists of three unit cells on top of the radiating patch element. This combination of UWB antenna and HSRR gives double-negative characteristics which increase the sensitivity of the UWB antenna for the pH sensor. The proposed ultrawideband antenna metamaterial sensor was designed and fabricated on FR-4 substrate. The electrical length of the proposed metamaterial antenna sensor is 0.238 × 0.194 × 0.016 λ, where λ is the lowest frequency of 3 GHz. The fractional bandwidth and bandwidth dimension ratio were achieved with the metamaterial-inspired antenna as 146.91% and 3183.05, respectively. The operating frequency of this antenna sensor covers the bandwidth of 17 GHz, starting from 3 to 20 GHz with a realized gain of 3.88 dB. The proposed HSRR-based ultrawideband antenna sensor is found to reach high gain and bandwidth while maintaining the smallest electrical size, a highly desired property for pH-sensing applications.

Compact microstrip patch antenna for multi-service wireless communications

A compact slotted circle microstrip patch antenna is presented for the ultra-wideband applications and other multiple wireless communications. The antenna, consisting of a slotted partial ground and a slotted circular patch, covers wider frequency band than the Ultrawideband (UWB). The prototype is fabricated on an FR4 substrate having a thickness of 1.60 mm with the relative permittivity of 4.6 and dielectric loss tangent of 0.02. The antenna has a compact physical size of 28 mm × 18 mm and electrical size of 0.37λ × 0.24λ. The antenna achieves 10 dB return loss (VSWR ≤ 2) from 4.0 GHz to 19.80 GHz with 132.77% fractional bandwidth. The antenna shows a consistent omnidirectional radiation pattern with 2.85 dBi of average gain. As the antenna covers a wide bandwidth, it can be used in the high fidelity short pulse applications. Moreover, the antenna can be used in ultra-wideband (UWB) communications along with other communications channels such as C-band (4–8 GHz), X-band (8–12 GHz), Ku-band (12–18 GHz), ISM band, Wi-Fi, WLAN, WiMAX, and MVDDS wireless communication systems.

Bandwidth performance analysis of different glass's dielectric permittivity on reflectarray radiating element

This paper presents the performance of bandwidth from a triangular loop shape radiating element stacked on a glass with variation of dielectric permittivity values. In this study, the dielectric permittivity value of the glass was varied from 1.5 to 10. A Kapton film (radiating element) was positioned on top of the glass and grounded with a copper layer. The radiating element was designed to operate at Ku-band frequency range. Simulation results from the CST microwave studio showed that a small dielectric permittivity value improve the reflectarray element bandwidth significantly.