A comparison of various double loops frequency selective surfaces in terms of angular stability

This paper presents the comparison of Frequency Selective Surfaces (FSS) structure performance based on three different double loops: square, circular and hexagonal structures. The simulation process of the double loops FFS structures are carried out by using the Computer Simulation Technology (CST) Microwave Studio software. The dielectric substrate used in the simulation is the FR-4 lossy substrate

Design of Triple-band Dipole-type Antenna with Dual-band Artificial Magnetic Conductor Structure

A design of dual-band high-impedance surface called Artificial Magnetic Conductor (AMC) is presented. The AMC is designed to resonate at 0.92GHz and 2.45GHz. In this paper also, the design parameters that influence the AMC frequencies are discussed. The designed AMC then is incorporated with the designed triple-band printed dipole antenna (operating at 0.92GHz, 2.45GHz and 5.8GHz). Here, the performance of the dipole antenna with 2 and 4 unit cells of 0.92GHz and 2.45GHz AMC ground plane are presented. The reported results show that, by applying the AMC structure as a ground plane for the printed dipole antenna, the gain of the dipole antenna can be increased due to the attracting feature of the AMC surface that provide in-phase reflected waves with the incident waves

Low loss waveguide-based Butler matrix with iris coupling control method for millimeterwave applications

This paper proposes a low loss 4×4 Butler matrix based on rectangular waveguide cavity resonators technology for millimeterwave beamforming network using iris coupling method. This method has the advantage of controlling the electrical fields and the coupling factor inside a complex medium such as waveguide cavity resonators. The coupling factor of 6 dB for 4×4 Butler matrix is achieved by tuning the iris coupling k-value between the waveguide cavity resonators. Thus, avoiding a higher phase difference losses and component losses at upper millimeterwave bands. To validate the proposed method, CST software simulations are performed under several iris coupling k-values to achieve a 6 dB coupling factor. Then, the proposed 4×4 Butler matrix is 3D metal printed using selective laser melting (SLM) technique. The measured reflection and isolation coefficients are observed below −10 dB, with coupling coefficients ranging between −6 and −7 dB. The phase differences of −42.02°, 42.02°, −130.95°, and 133.3° are achieved at the outputs. It confirmed that using this proposed method has the superiority over the conventional microstrip and waveguide coupling methods by a 1 dB coupling factor loss and a 3° phase difference error

Keberkesanan penggunaan edubase dalam kalangan pelajar teknikal yang berbeza gaya kognitif, afektif dan psikomotor di Politeknik Malaysia

Bahan bantu pengajaran yang digunakan secara bersesuaian dengan pelajar menyumbang kepada perkembangan pembelajaran mereka. Dalam dunia pendidikan teknikal, aspek kognitif dan psikomotor turut memberi kesan kepada kualiti pembelajaran pelajar. Kajian ini membincangkan tentang kesan penggunaan EDUBASE terhadap pencapaian dan minat pelajar yang mempunyai gaya kognitif, afektif dan psikomotor yang berbeza dalam topik Electromagnetism. Seramai 70 orang pelajar politeknik yang terdiri daripada 33 pelajar kumpulan rawatan dan 37 pelajar kumpulan kawalan telah terlibat dalam kajian yang menggunakan kaedah kuasi-ekperimen ini. Ujian kognitif, psikomotor, ujian pra-pasca dan kaji selidik telah diagihkan untuk memantau kesan penggunaan EDUBASE terhadap pelajar. Dapatan kajian ini telah dianalisis dengan menggunakan statistik MANCOVA, korelasi Pearson dan skor min. Hasil dapatan dalam kajian ini menunjukkan bahawa terdapat perbezaan yang tidak signifikan secara statistik bagi skor pelajar kumpulan kawalan dan kumpulan rawatan. Namun, skor min menunjukkan kumpulan rawatan memberikan skor yang lebih cemerlang dan minat mereka juga turut meningkat dalam topik pembelajaran tersebut berbanding pelajar yang mengaplikasikan pembelajaran secara konvensional. Selain itu, hasil dapatan kajian juga menunjukkan terdapat hubungan yang signifikan terhadap minat dan pencapaian. Di samping itu, EDUBASE yang diaplikasikan telah memenuhi keperluan dan minat pelajar. Secara ringkasnya, hasil kajian ini menunjukkan bahawa penggunaan EDUBASE sebagai alat bahan bantu mengajar dilihat berkesan dalam memberikan kecemerlangan pencapaian dan meningkatkan minat pelajar politeknik terhadap topik Electromagnetism

Floral structure for textile-based metamaterial absorber

Based on an annulled circle structure metamaterial absorber (MMAb), a floral structure MMAb design is proposed for performance improvement especially on absorptivity. Since the initial purpose of designing the MMAb is for hiding one’s existence from electromagnetic motion detector, it is expected that the MMAb will has flexibility as one of its characteristics. The MMAb composes of textile-based substrate in between floral structure at the top and ground plane at the bottom, based on metallic plate. The targeted center frequency is 10.525 GHz and through series of simulation done in CST Microwave Software, the MMAb can reach up to 97.03% of absorptivity. The operating angle can be extended at least 68o before its absorptivity deteriorated below 80%. In addition, the proposed MMAb has a high absorptivity regardless of the polarization angle of the electromagnetic waves

Compact Digital Television (DTV) Antenna for Indoor Usage

A compact indoor digital antenna for digital terrestrial television is proposed. The design of the antenna begins with the material selection to construct the antenna by using CST software with a standard monopole antenna design. The antenna is then simulated and optimized. A bandwidth of 290 MHz (46.14%) between 500 MHz and 790 MHz is achieved with the antenna gain more than 3 dBi. Simulated results is used to demonstrate the performance of the antenna. The simulated return losses, together with the radiation patterns and gain are presented and discussed

Compact Digital Television (DTV) Antenna for Indoor Usage

A compact indoor digital antenna for digital terrestrial television is proposed. The design of the antenna begins with the material selection to construct the antenna by using CST software with a standard monopole antenna design. The antenna is then simulated and optimized. A bandwidth of 290 MHz (46.14%) between 500 MHz and 790 MHz is achieved with the antenna gain more than 3 dBi. Simulated results is used to demonstrate the performance of the antenna. The simulated return losses, together with the radiation patterns and gain are presented and discussed

Compact patch MIMO antenna with low mutual coupling for WLAN applications

A compact triband microstrip patch MIMO antenna is proposed for WLAN applications. The antenna consists of two patches antenna elements, which are orthogonally placed to each other for high isolation at 2.4, 2.8 and 5.8 GHz frequency bands. On its ground plane, a Complementary Split Ring Resonators (CSRRs) is etched for size reduction and multiband generation. The proposed compact MIMO antenna covers an entire size of 58 x 45 x 1.6 mm3, with the patch size of 13.3 x 17.1 mm2. A 79% size reduction at 2.45 GHz was achieved for miniaturization, with a very low mutual coupling (S21 and S12) of -32 dB at all bands

Slot implementation on second iteration of fractal log periodic dipole antenna for uhf band application

In this paper, the design of the second iteration of Log Periodic Fractal Koch Antennas (LPFKA) with and without slot implementation is designed for Ultra High Frequency (UHF) band applications. The slot implementation is applied on each of the radiating elements to reduce the antenna's size and to prevent the shifting of a lower frequency to a higher frequency. The antenna is operated at a frequency between 0.5 GHz and 9.0 GHz. The Computer Simulation Technology (CST) software was used to design and simulate the antenna. The performance of the antenna such as reflection coefficient, radiation pattern and gain have been analyzed. The antennas have been fabricated using an FR4 laminated board with a dielectric constant of 4.6, tangent loss of 0.019, and a thickness of 1.6mm. The results show a positive outcome, with a stable radiation pattern over the operational bandwidth and a reflection coefficient of less than -10 dB for the designed frequency

Wideband antenna with reconfigurable band notched using EBG structure

A wideband antenna with band notch function using electromagnetic bandgap (EBG) structure is proposed. The antenna is capable of reconfiguring up to three band notch operation. Three EBGs are aligned underneath the feed line of the wideband antenna. The transmission lines over EBGs unit cells perform as a band stop filter. A switch is placed on each of the EBG structure, which enables the reconfigurable band stop operation. The simulated and measured reflection coefficients, together with the radiation patterns, are shown to demonstrate the performance of the antenna