User Interface and RF-Front End Design for Radio Direction Finding-Miniature Unmanned Air Vehicles (RDF-MUAV)

Radio direction finding perform better at high altitude due to greater line of sight coverage. In this paper, the radio direction finding-miniature unmanned air vehicles (RDF-MUAVs) platform able to localize the beacon by accessing the direction of signal and report it back to the ground station immediately, improving search and rescue operations. RDF-MUAV system divided into four major part; RF front end design; RF software design; ground station design; and user interface (UI). This paper focuses on two out of the four major parts, which designing a good UI and RF front end to be integrated into the system. The UI is designed using Linux, Apache, MySQL, PHP (LAMP) architecture in Raspberry Pi platform that can display accurate data obtained from RDF-MUAVs. The UI is based on HTML which is lightweight, modifiable and can be accessed through smartphone, tablets, or personal computer. In the antenna design, phase direction finder method is chosen. The rotation of antenna can be done by moving the UAV to obtain the bearing to the source signal. Proposed type of antenna is Yagi-Uda antenna due to its high gain and relatively small size. The folded dipole is chosen as the driven element of the antenna due to its bandwidth characteristics and directivity. Result shows the function-al bandwidth is 200MHz which can accept electromagnetic waves from 500MHz to 600MHz and 900MHz to 1000MHz. Overall, the design implementations provide a feasible system in search and rescue operation

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

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

UHF RFID antenna tag design and analysis for antenna miniaturization

This paper proposes four designs of UHF RFID antenna tag with two different radiating element, copper and aluminum, for antenna miniaturization. The main contribution of this work is the unique design that involves a meander line traced in a variety shape of a bowtie antenna. The UHF RFID band is achieved by reshaping a 900 MHz straight line dipole antenna into the form of a bowtie, thus reducing the size of the antenna significantly while maintaining the operating frequency. The effectiveness of the method is tested in multiple steps. First, the antenna tag designs are run through CST software simulations and optimized to achieve desired outcome. Next, the designs are transferred to Silhouette Studio software to be fabricated using a cutting machine, and finally measured using a vector network analyzer. The comparison between the measurement result of the reflection coefficient and the radiation pattern to their respective simulation results shows that they have a good agreement between each other. With further research and improvements, the size of the antenna tag could be further reduced while maintaining or even improving the performance of the antenna tag

A Novel Right Handed Circular Polarization Folded Reflectarray Antenna at 60 GHz

A novel right-handed circular polarization (RHCP) folded reflectarray antenna with optimized parameters is presented at 60GHz. The RHCP folded reflectarray antenna is designed using left handed circularly polarized selective surface (LHCPSS) Pierrot unit cell. Through simulation, it is shown that the antenna operates well at 60GHz. The maximum antenna directivity is 19dB with a reflection coefficient below -15dB. The radiation patterns showed good responses with side lobes level below -10dB. In addition, the best axial ratio at 60GHz is achieved as 0.75dB

Bidirectional Antenna for 2.4-ghz WLAN Application Inside Train

In this paper, a bidirectional antenna is presented for a WLAN application inside monorail train. The Yagi Uda antenna has directional characteristic that is suitable for the long path service area. The design concept of the proposed antenna has two directional antennas combined pointed in opposite direction which only involves the driven element and directors. The Yagi Uda design of bidirectional antenna operates in the frequency band of 2.4 GHz. The antenna is proposed with a thickness of 1.6mm and relative permittivity of 4.3 on FR4 substratum. Resonant frequency is set at 2.42 GHz with a bandwidth of 390 MHz from simulation work. The proposed antenna also met the estimated antenna bandwidth at a range of 2.23 GHz-2.63 GHz, and the bidirectional pattern. Both simulated and measured result are well matched

Band-pass Filter with Harmonics Suppression Capability

This paper presents a Band-pass Filter (BPF) with a very wide suppressions band. The filter design is based on a modified U-shaped slot. Two pair of U-shaped slots is used to ensure that the filter can suppress the unwanted frequencies up to 4th harmonics. In order to achieve sharp skirt, two transmission zeroes are created near the passband area. Additional transmission zeroes are introduced to deepen the stopband area. Therefore, the passband range starts from 1.3 to 3.3 GHz and the stopband range from 3.3 GHz up to 9 GHz are achieved. The filter performances are verified through simulated and measured results

High capacity and miniaturized flexible chipless RFID tag using modified complementary split ring resonator

This paper aims to produce a high data capacity and miniaturized flexible chipless RFID tag based on the frequency signature using the Modified Complementary Split Ring Resonator (MCSRR). The proposed 19 bits chipless RFID tag using the frequency shifting technique consists of five slotted overlaying MCSRR with Different Width (MCSRR with DW) structures and the dimension of 48 mm x 48 mm. The structure is designed by using a flexible (Polyethylene Terephthalate ) PET substrate with permittivity of 0.2. The operating frequency is between 0.9 GHz and 2.7 GHz. The advancement of slotted overlaying MCSRR with DW structures has successfully miniaturized the chipless RFID tag structure to about 107 mm2/ bit, 0.02/2 mid =bit and 0.09 GHz/bit by maximizing the number of resonators in a limited space and minimizing the frequency separation between the resonators. The omnidirectional tag antenna is incorporated with the proposed MCSRR structure using the retransmission measurement method. The log-periodic antenna with a gain of 5-7 dBi is used for this measurement to improve the range distance between tag and reader system. Based on the retransmission measurement involving the antenna tag, the 19 bits chipless RFID tag which consists of five MCSRR with DW structures can be detected with a maximum range distance of 30 cm and a power transmitted level of 30 dBm

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