Sarah Yasmin Mohamad

Selective High Impedance Surface Active Region Loading of Archimedean Spiral Antenna

We show that a significant increase in the gain and front-to-back ratio is obtained when different high impedance surface (HIS) sections are placed below the active regions of an Archimedean spiral antenna. The principle of operation is demonstrated at 3, 6, and 9 GHz for an antenna design that employs a ground plane composed of two dissimilar HISs. The unit cells of the HISs are collocated and resonant at the same frequency as the 3- and 6-GHz active regions of the wideband spiral. It is shown that the former HIS must also be designed to resonate at 9 GHz to avoid the generation of a boresight null that occurs because the structure is physically large enough to support higher-order modes. The improvement that is obtained at each of the three frequencies investigated is shown by comparing the predicted and measured radiation patterns for the free space and HIS-backed antenna.

Rain Rate Distributions for Microwave Link Design Based on Long Term Measurement in Malaysia

With the rapid growth of communications via the Internet, the need for an effective firewall system which has not badly affect the overall network performances has been increased. In this paper, a Field Programmable Gate Array (FPGA) -based firewall system with high performance has been implemented using Network FPGA (NetFPGA) with Xilinx Kintex-7 XC7K325T FPGA. Based on NetFPGA reference router project, a NetFPGA-based firewall system was implemented. The hardware module performs rule matching operation using content addressable memory (CAM) for higher speed data processing. To evaluate system performance, throughput, latency, and memory utilization were measured for different cases using different tools, also the number of rules that an incoming packet is subjected to was varied to get more readings using both software and hardware features. The results showed that the designed firewall system provides better performance than traditional firewalls. System throughput was doubled times of the one with Linux-Iptables firewalls.

Design of a Circular Patch Antenna for 3D Printing

This paper proposes an innovative circular patch antenna that resonated at 2.34 GHz using 3D printing technique. The purpose of using 3D printing is a way to reduce cost and time in fabrication of the antenna. By introducing a new material to the subject which is Acrylonitrile Butadiene Styrene (ABS) as the substrate of the antenna, the cost can be greatly reduced. Furthermore, a coaxial probe feed is used and it is said to be easy to fabricate, matched and has low spurious radiation. The feeding method that has been used in this research is a coaxial line feed where the inner conductor of the coax is connected to the patch meanwhile the conductor is connected to the ground. This antenna is designed on an ABS substrate with εr = 2.74 and it has a loss tangent of 0.007. The thickness is said to be 3.25 mm. In addition to that, it has the return loss (S11) of 24.3 dB at 2.34 GHz. The whole designation of the antenna is by using Computer Simulation Technology (CST) software. The anticipated design of a circular patch antenna can be extended to conformal antenna and therefore, the prototype will become more compact, efficient and robust.