nan Chairunnisa

Size reduction of UHF planar inverted-F antenna with patch geometry modification

This paper deals with the design and experimentation of ultra high frequency (UHF) planar inverted-F antenna in reduced size with patch geometry modification. The antenna which intended to operate around frequency of 920MHz for medical implant application is deployed on a 0.8mm thick of FR4 Epoxy dielectric substrate. Prior hardware realization, the parameters of antenna including reflection coefficient, gain, and radiation pattern as well as its physical dimension are investigated numerically to obtain the optimum performance design. From experimentation, it shows that the realized antenna which takes a rectangular spiral shape for its patch and has the total dimension of 15mm × 15mm resonates at frequency of 915MHz with gain and bandwidth of -27.03dBi and 17MHz, respectively.

Numerical analysis for wave propagation in circular waveguide using cylindrical coordinate system-based FDTD method

Several problems of electromagnetic fields can be solved by various numerical methods. One of the methods is finite-difference time-domain (FDTD) where in this work is addressed for modeling a hollow circular waveguide and its wave propagation analysis. Different from other FDTD methods which is usually based-on Cartesian coordinate system, in current paper the cylindrical coordinate system is employed as a basis for computation. The method in two- and three-dimension (2D and 3D) systems is employed to model a circular waveguide which has the radius of 50m and length of 100m. A sine wave modulated Gaussian signal with frequency of 3MHz is applied as a wave source for computation. To truncate the computation area, the second order absorbing boundary condition (ABC) is assigned at the outer side and the center of waveguide. From the numerical result, it shows that the amplitude of wave that propagates from the inner to the outer of waveguide decreases along the radius due to the grid size in cylindrical coordinate system based-FDTD method both in 2D and 3D systems.

Size reduction of compact dual-band antenna based on metamaterials

A compact dual-band antenna based on metamaterials with emphasizing in size reduction is proposed in this paper. The proposed antenna that takes a U-shaped patch is designed to operate in dual frequency bands of WiMAX, 2.3GHz and 3.3GHz. In the design, metamaterials with composite right-left handed transmission line approach is used to implement the proposed antenna. The antenna is fed by use of microstrip line feeding technique and deployed on FR-4 Epoxy substrate with the relative permittivity of 4.3 and the thickness of 0.8mm. To demonstrate the size reduction capability, the metamaterials-based antenna will be compared with other 2 microstrip antennas that resonate at the same resonant frequency, namely half ground plane antenna and full ground plane antenna. Here, the microstrip antennas are also deployed on similar dielectric substrate with the same relative permittivity. These 3 kind antennas are then compared each other in terms of physical size, return loss, bandwidth, gain, and radiation pattern. From the comparison, it is shown that the employment of metamaterials for antenna implementation is achieving the wider bandwidth for both frequency bands and the smaller antenna size up to 28% and 70% compared to the microstrip half ground plane and full ground plane antenna, respectively.

Beam reconfiguration of capacitor-based square patch antenna array

In this paper, a beam reconfiguration of antenna array composed of four elements microstrip square patch antenna is proposed by use of capacitor chips. The array of antenna which is deployed on an FR4 Epoxy dielectric substrate is intended to operate at center frequency 2.4GHz for wireless communication application. The four patch antennas are arranged in a horizontal array employing microstrip line as its feeding network. There are two configurations of capacitor chips incorporated into the antenna array, the first with capacitances of 1pF, 10pF, 10pF, 1pF and the second with capacitances of 0.5pF, 1.5pF, 1.5pF, 0.5pF for each feeding line connected the antenna patch. The beam reconfiguration is shown by characterizing the antenna array and comparing the result for an array without and with capacitor chips. From the measured results, it shows that the magnitude and phase of reflection coefficient as well as the radiation pattern of proposed antenna array are influenced by the presence of capacitor chips. The first configuration of capacitor chips changes the reflection coefficient at frequency of 2.46GHz from -17.18dB to -9.68dB, the phase shift into 81.48°, and a slight deflecting beam maximum angle of 10°. Whilst from the second configuration, the result shows the reflection coefficient of -7.46dB at frequency of 2.48GHz, shift of antenna phase into 73.89°, and deflection of beam angle up to 20°.

Return loss enhancement of surface resistors loaded microwave radar absorber

In this paper, return loss enhancement of a compact ultra-thin microwave radar absorber is demonstrated, The absorber is designed using textured surface technology comprised of a high impedance surface (HIS) positioned directly behind the anisotropically resistive-elements interconnecting a textured surface of square patches. By the selection of appropriate choice of the required surface resistors based on elementary circuit principles the return loss of absorber can be significantly improved. The properties of absorber are numerically characterized under normal incident using a parallel plate waveguide (PPW) simulator. It is demonstrated for this arrangement 27.09dB at 3.14GHz reflection loss can be obtained with an effective working bandwidth of up to 10% at 10dB reflection loss. In addition it is shown that the bandwidth is insensitive to the small different values of resistive-element.

High gain RF amplifier for very low frequency receiver application

Due to the wide usage of very low frequency (VLF) wave for research on natural phenomena such as lightning, earthquake, and weather, a receiver for VLF application particularly with high-gain is absolutely required. This paper discusses about designing, realizing and characterizing a high gain radio frequency (RF) amplifier for VLF receiver application. The proposed amplifier which is designed using a junction field-effect transistor (JFET) of 2SK170 and an operational amplifier (OpAmp) of OP27 is intended to work at frequency range below 50kHz. After achieving the optimum design, the hardware realization is then carried out by deploying the designed amplifier on a printed circuit board. From the experimental characterization, it shows that the measured gain of realized amplifier at frequency of 19.8kHz satisfies with the design criteria and is 46.003dB with 1-dB compression point of -24dBm.

FSS-based planar filter with capacitor chips for antenna frequency selection

In this paper, the design of planar filter based on FSS structure workable at three different frequency allocations is proposed. The FSS structure which is constructed using inductive and capacitive grids is designed to have frequency selection feature for incoming waves from antenna at operating frequency of 1.575GHz and 1.8GHz. Meanwhile at operating frequency of 2.4GHz, the incoming waves will be always passed. Some capacitor chips are incorporated into the grids to obtain the tuning frequency of selection. From the measured results, it shows that the FSS-based planar filter which is implemented on a 0.8mm thick FR4 Epoxy dielectric substrate with the dimension of 135mm × 60mm are not affected by the capacitance values for operating frequency of 2.4GHz. Whilst for operating frequency around 1.8GHz, the different capacitance values have shifted frequency response which is larger than for operating frequency of 1.575GHz.

Capacitor-based phase shifter for 8 elements antenna feeding network

This paper deals with the development of 8 elements capacitor-based phase shifter for 2.4GHz antenna feeding network. The phase shifting is achieved by using loaded-line phase shifter technique implemented by placing capacitor chips at the edge between 50Ω and 70.71Ω transmission lines. The feeding network consists of microstrip transmission lines and matching impedance lines designed using a quarter wavelength transformer method and deployed on an FR4 Epoxy dielectric substrate with relative permittivity of 4.3, thickness of 1.6mm and dimension of 50mm × 300mm. The feeding network is configured at 4 different scenarios with various capacitance values. The first scenario is no capacitor chips added into the microstrip lines; while at the second and third scenarios, 1pF and 10pF capacitor chips are put on each line of output port, respectively; and at the forth scenario, capacitor chips with the consecutively value of 10pF, 3pF, 1pF, 1pF, 1pF, 1pF, 3pF, 10pF are placed for each microstrip line. From the result, it shows that the proposed capacitor-based phase shifter for 8 elements antenna feeding network is suitable for 2.4GHz operating frequency with the measured phase shifting up to 40° for capacitance value of 1pF.

Wireless electronic information board for tsunami early warning system based on FM radio

This paper discusses an early warning system of wireless electronic information board based on frequency modulation (FM) radio to display the tsunami disaster risk visually. The system will be implemented in Cilacap District located on the confluence of two major plates. The display of proposed system is designed in multicolor using dot matrix panel P10 which has 32 × 16 pixels resolution. To be implementable for electronic information board, the display requires 96 × 48 pixels in minimum specification and is controlled using microcontroller. A master station located at the data center of Local Disaster Relief Agency (Badan Penanggulangan Bencana Daerah, BPBD) will transmit the data modulated using frequency shift keying (FSK) method through FM radio transmitter. Then, some work stations at the remote areas will receive the FM radio signal to be demodulated into data and further processed by microcontroller to be displayed. From the characterization, it shows that the proposed system successfully transmits the data with baud rate of 4800 bits per second (bps) with mark and space frequencies of 16.8kHz and 15.4kHz, respectively. Furthermore, bit error rate (BER) performance of the system is 0.2% which means there are 2 error bits in 1000 bits transmitted.

Dual polarization X-band square horn antenna

Nowadays, the antenna started to evolve along with the needs of the application of the antenna, including the horn antenna. Several types of antennas ever made using only one polarization with a rectangular shape that is applied to the S-band and C-band frequency and the antenna size is large enough. This paper aims to design dual polarization square horn antenna that will meet the characteristics of the antenna as radar. The minimum requirements of the radar antenna are VSWR ≤ 2, gain 10–30dBi, Return Loss < −10dB. So this paper deals to achieve the minimum requirements. Antenna is designed with a size of 23mm × 23mm with an overall length of 120mm. To achieve double polarization excitation, 2 pieces of feeds using SubMiniature connector version A (SMA) with a distance of 29,5mm are positioned orthogonally from the waveguide-short end. Based on simulation results, the best configuration for the development of a square horn antenna are on 9GHz frequency, antenna has return loss of −46dB and the gain value of 13dBi. From the fabricated antenna measurement, at 9,02GHz frequency the antenna has return loss value of −12,02dB and gain value of 17.59dBi.