Nornikman Hassan

Measurement of pyramidal microwave absorbers using RCS methods

In this work, a commonly used measurement techniques were used to define the reflection loss performance of pyramidal microwave absorbers mounted on a wall. The technique is namely, Radar Cross Section (RCS) measurement method. Six set of pyramidal microwave absorbers and flat square absorbers were installed at one side wall, in an RF shielded room in order to investigate the performance. Two types of cable losses measurement techniques were applied to compare its performance under different loss conditions. The reflection loss values resulting from this investigation were then analyzed and discussed.

Circular Polarized Patch Antenna for 1.8 and 2.4 GHz Applications

This paper presented a patch circular polarized antenna for GSM technology at 1.8 GHz and WLAN technology at 2.4 GHz. A traveling wave microstrip array antenna consisting of square truncated patch operated as circular polarized has been designed, fabricated and measured. The inter element spacing; length and width of the square and circular patches of the array antenna were optimized by successive simulations using the CST software. This antenna had radiated at 1.8 and 2.4 GHz of resonant frequency with −38.563 and −24.967 dB of return loss respectively. The axial ratio for RHS circular polarized is 0.95 < 3 dB at 2.4 GHz.

Investigation of impedance modeling for a unit cell of the circle loop Frequency Selective Surface at 2.4GHz

In this paper, we present a mathematical impedance modeling for a unit cell of the circle loop Frequency Selective Surface (FSS) structure. The unit cell of the circle loop FSS is designed and simulated based on industrial, scientific and medical bands (ISM) standard by using the CST Microwave Studio software. The configuration of FSS is simulated for two types; single layer and dual layer FSS. Based on physical parameters of the design structure of the FSS, real and imaginary component of the design has been modeled mathematically.

X band parallel coupled- line with dumbbell dgs filter for radar applications

Microwave filter is a kind of device, which can separate microwave signals with different frequencies. The filter has been utilized widely in many fields such as communication, signal processing, radar and other related fields. An X-band filter using parallel coupled-line technique with DGS is designed. The purpose of this paper is to observe the performance of band-pass filter with defected ground structure operating at a frequency of 10G Hz. The filter designed is run by simulation using Advanced Design System (ADS). Initially, the mid-band frequency is set to 10G Hz. The filters design and structure is based on the Chebyshev prototype characteristic. The characteristics can be visualized through the response of the reflection coefficient and transmission coefficient.

Performance Enhancement of Inverted Suspended Circular Polarized Antenna with the Integration of Metasurfaces (MS) Structure Technique

In this paper, it is proposed to use metasurface (MS) structure for the miniaturization and antenna performance enhancement of inverted suspended circular patch with square slot. The antenna was designed based on inverted suspended circular patch with air gap between the patch substrate and copper ground plane is separated with distance of 10 mm (Design A). L-probe technique is used for the antenna design and by using Design A the MS structure is put at the top of the antenna with air gap separation of 1 mm (Design B). The proposed antenna had been designed and simulated by using Computer Simulation Technology (CST) Software. Target application for this antenna design is for Wireless Local Area Network (WLAN) at operating frequency of 2.4 GHz. Simulation and measurement antenna performances in term of return loss, resonant frequency, bandwidth, realized gain, directivity, axial ratio, total efficiency and radiation pattern at the design frequency are investigated and discussed. Based on the result, with the integration of MS, Design B antenna substrate size can be reduced by 23.45 %, yet maintaining the similar performance. Other than that, axial ratio bandwidth (ARBW) for Design B also increases up to 68.8 % from 58.4% (Design A) with impedance bandwidth 627 MHz which is 71 MHz wider than Design A.

Design of Circular Polarized Antenna by Using Inverted Suspended Circular Patch Design for WLAN Application at 2.4 GHz

In this paper, an inverted suspended circular patch antenna with circular polarization is proposed for wireless local area network (WLAN) operating at 2.4 GHz frequency. The antenna was designed based on inverted suspended circular patch with an air gap between substrate and ground plane layer at distance of 10 mm. L-probe technique is used in this antenna design in order to feed the signal from SMA probe to the feedline of the circular patch structure. The design and simulation process are done by using Computer Simulation Technology (CST) software. Antenna performances in term of return loss, resonant frequency, bandwidth, gain, directivity, axial ratio, total efficiency and radiation pattern at 2.4 GHz frequency are discussed. The comparison result of simulation and measurement show that the proposed circular polarized antenna obtained bandwidth more than 100 MHz with gain and return loss achieved more than 5 dB and -13 dB at 2.4 GHz.

Investigation of Circular Patch Metasurface (MS) on Inverted Suspended Circular Polarized Antenna

In this paper, an analysis of different stage of circle patch metasurface (MS) on basic structure of inverted suspended circular patch with square slot antenna design is proposed to investigate its effect toward the basic antenna performance. The basic antenna was designed based on inverted suspended circular patch with air gap separation between the patch substrate and copper ground plane at a distance of 10 mm (Basic design). Then, different design of MS structure (Design A, B, C & D) consisting of 5 x 5 unit cell of homogeneous periodic element is place in between the air gap of the basic antenna. All of MS design is located at a fixed position to study the effect of different MS shape to the Basic antenna performance. The proposed antenna and MS structure had been designed and simulated by using Computer Simulation Technology (CST) Software. Target application for this antenna design is for Wireless Local Area Network (WLAN) at operating frequency of 2.4 GHz. Simulation performances in term of return loss, resonant frequency, bandwidth, realized gain, directivity, axial ratio, total efficiency and radiation pattern at the design frequency are investigated and discussed. From observation on simulation result, resonant frequency of Basic design is shifting to a lower frequency from 2.4 GHz to 2.19 GHz (Design C and D) with the integration of the MS structure. Design C obtained the widest axial ratio bandwidth among all of other design with 1380 MHz covered from 1.31 GHz to 2.69 GHz. Directivity for Basic designs at 2.4 GHz increases from 7.94 dBi to 8.17 dBi, 8.16 dBi, 8.15 dBi and 8.06 dBi (Design A, B, C and D) respectively.

2 × 1 Circular Array Patch Antennas with Double Circular Slots for WLAN Application

The purpose of this paper is to presents entire design of 2 × 1 circular array patch antenna for WLAN application of 2.4 GHz. Circular array with double circular slots microstrip antenna modeled due to the low profiles and easy to fabricate. The circuit was designed by using CST Microwave Studio for the entire dimension. The simulation results of the antenna are done to observe the return loss, radiation pattern, gain, directivity and bandwidth performance. This proposed circular array patch antenna has radiate −24.707 dB at resonant frequency of 2.40 GHz. The bandwidth of this antenna is 53 MHz while the gain is 8.521 dB. Two parametric studies on the effect of the two different circular radiuses (R 1 and R 2 ) are done in this work.