Samsul Haimi Dahlan

Size Reduction and Multiband Characteristic Using Koch Fractal Dipole

The Koch fractal dipole antenna is designed, simulated and fabricated for operating at 900MHz frequency band. By using Koch fractal antenna mathematic equation and some consideration, the desired resonant frequencies can be achieved. The designed antenna is started with developing microstrip dipole antenna for the same frequency operation. The size of Koch fractal dipole is reduced around 40% compactness compared to microstrip dipole. A multiband characteristic is investigated until third iteration with identication angle, thetas = 60deg trace width, W = 1mm and fabricate onto FR-4 substrate using SMA connector

A compact flat lens antenna with aperture-coupled patch elements

A compact 7 × 7 flat lens antenna design for X-band applications is presented in this paper. A new design with aperture-coupled E-shaped patch elements at 10 GHz is simulated and analyzed. This antenna design is realized by using two back-to-back printed patches with slotted common ground plane and feed horn antenna. The transmission loss obtained of 2.2 dB is sufficiently low. A 320° transmission phase range for the E-shaped patch unit cell is achieved with less than 1.5 dB of deviation in the transmission loss level.The proposed design uses a simple technique and less manufacturing complexity for transmission phase control.

Miniaturized Low Pass Filter Using Modified Unifolded Single Hairpin-Line Resonator for Microwave Communication Systems

A compact low pass filter (LPF) using single folded stepped impedance hairpin resonator is proposed. It consists of an internally coupled-line section which acts as a phi-connection capacitors, and a transmission line which act as a parallel connected inductors. Together, an elliptic low pass filter configuration is achieved. The internal coupled lines length is tuned to adjust the cutoff frequency as well as the spurious frequency response. The length of the inductive transmission line section is maintained. Simulation investigations revealed that as the coupled line length increases, the magnitudes of the spurious frequency responses reduced and the locations were shifted to higher frequencies. Hence, wider stopband bandwidth area is achieved. It is also interesting to note that small coupled line extension introduced at the original coupled line has improved the profile further. Using electromagnetic simulation software, it is shown that a compact LPF with 2 GHz cutoff frequency and band reject of 3 GHz to 10 GHz has been successfully designed and simulated

Analytical Solution for Maximum Differential-Mode Radiated Emissions of Microstrip Trace

In this paper, a novel analytical solution was presented for estimating the maximum differential-mode (DM) radiated emission from electrically long PCB traces using transmission-line theory, travelling wave antenna, and far-field magnetic vector potential. The analytical solution was simplified for matched load in which only forward travelling wave was considered. Additionally, a simple expression for predicting maximum DM-RE from electrically short traces was obtained using proper simplifications. The results from the proposed analytical model were then compared to the results obtained from 3-D HFSS full-wave simulation and the measurement performed in a semianechoic chamber. Good agreements within ±3 dB were obtained over a wide range of frequency.

Design Sierpinski Gasket Antenna for WLAN Application

This project mainly discussed on designing and fabricating the antenna using fractal concept to obtain the dual band resonant frequency at 2.4 GHz and 5.8 GHz for wireless local area network (WLAN) application. The application of fractal geometry can be used to miniaturize the antenna due to their self-similarity and this project focusing on designing the Sierpinski gasket antenna for first iteration. The antenna had been simulated using CST microwave studio, while the fabricated antenna had been tested using network analyzer. The results of both antenna simulation and measurement are in good agreement with the design expectation. The antenna was fabricated on printed circuit board (PCB) using epoxy/ glass (FR- 4) substrate with 30cm by 30cm metallic copper ground plane.

Compact and Low-Profile Textile EBG-Based Antenna for Wearable Medical Applications

A compact wearable antenna with a novel miniaturized electromagnetic bandgap (EBG) structure at 2.4 GHz for medical application is presented in this letter. The design demonstrates a robust, compact, and low-profile solution to meet the requirements of wearable applications. The EBG structure reduces the back radiation and the impact of frequency detuning due to the high losses of human body. In addition, the structure improves the front-to-back ratio (FBR) by 15.5 dB. The proposed compact antenna with dimensions of

Transmission of Microwave Signal through Metal-Oxide Thin Film of Energy Saving Glass Using Different Shape of Frequency Selective Structure

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Design of folded half wave resonator

yields an impedance bandwidth of 27% (2.17–2.83 GHz), with a gain enhancement of 7.8 dBi and more than 95% reduction in the specific absorption rate. Therefore, the antenna is a promising candidate for integration into wearable devices applied in various domains, specifically biomedical technology.

Miniaturized internally-coupled hairpin-line bandpass filter

Metal oxide thin films are widely used for energy saving glass coating. This coating has the ability of blocking the infrared signal while being transparent to other visible part of the spectrum. However, there is one critical disadvantage of this metal oxide coating which it attenuates useful radio frequency and microwave signal such as GSM mobile signal, personal communication, GPS signal through them. These important microwave signals are fall within the range of 800 MHz to 2200 MHz. Frequency selective structure has been applied to solve the attenuation of microwave signal. With the adding of frequency selective structure, it can bring huge improvement of the transmission loss through it. Computer simulation using CST software is used to investigate the transmission loss through the metal oxide coated glass. The frequency selective structure will be etched out from the metallic oxide coated on the glass. Results showed that different shape of the structure will have different peak transmission loss through the glass. When cross dipole and circle shape been simulated using CST software, it can clearly see that the transmission lost and peak frequency had changed drastically. Then, triangle and pentagon shape also have different transmission through it. In addition, conductivity and electrical properties of coated metal oxide thin film is also very important. The transmission through the different ohmic sheet resistance of metal oxide thin film was also investigated. The sheet resistance value was obtained from the reported experimental results. Simulated results showed that full width half maximum, maximum transmission loss and peak frequency loss was very much dependent on the metal oxide sheet resistance. Therefore, the control of the thickness and oxygen content in metal oxide thin film are very much important to optimize the transmission loss through it for energy saving glass applications.

Rectangular patch with partial ground wearable antenna for 2.4 GHz applications

This paper presents the design of compact hairpin resonator operating at S-band. The chosen frequency is 2.45 GHz, suitable for wireless local area network (LAN) application. The resonator structure consists of internally coupled-line. Design parameters that affect the operating frequency and the first spurious frequency were investigated. The determination of impedance and length ratios are important prior to the design in order to achieve minimum resonator size. Investigations were performed to study resonators behavior for various sizes of internal coupled-line gap and length to the operating frequency. Bigger gap size and shorter coupled-line length caused the resonator to operate at a frequency higher than expected.