KMITL

Permanent URI for this communityhttps://dspace.kmitl.ac.th/handle/123456789/1

Browse

Search Results

Now showing 1 - 10 of 11

Some of the metrics are blocked by your
consent settings
Object Detection of Ground-Penetrating Radar in the Frequency Domain Using Three-Antenna System
(2022-05-01)
Kittiyanpunya, Chainarong
;
Krairiksh, Monai
An object detection method of ground-penetrating radar (GPR) in the frequency domain using three-antenna system is proposed in this study. The presented methodology utilizes the electromagnetic (EM) scattering from the object for identification using its natural poles. Two schemes of GPR system were examined. The first scheme was the conventional GPR comprising one transmitter and one receiver. The second scheme comprises two transmitters and one receiver, which the transmitters were excited by out-of-phase generators with each other. The simulations were initially performed using the three-antenna system for GPR. The results indicated that the natural poles in the scattering responses changed according to the characteristics of the object. For comparison, the three-antenna system for GPR was fabricated and experimented in comparison with the conventional GPR configuration. The experimental results revealed that the three-antenna configuration was able to mitigate the ground bounce and antenna coupling effects, while the conventional GPR was interfered by the effect of ground reflection and mutual coupling of the antennas. The three-antenna configuration is thus suitable to be the front-end before extracting the natural poles. In addition, the frequency domain method is compatible with the three-antenna system in the determination of the natural poles for identification. As such, the proposed system for investigating the response in the frequency domain is operationally appropriate in GPR system.
Some of the metrics are blocked by your
consent settings
Dual-Frequency Sensor for Thick Rind Fruit Quality Assessment
(2020-10-01)
Kittiyanpunya, Chainarong
;
Phongcharoenpanich, Chuwong
;
Krairiksh, Monai
This article proposes a novel multibeam dual-frequency sensor system to assess the quality of thick rind fruits based on phase difference between lower- and higher-frequency reflection coefficients ( Φ {12} ). The proposed sensor system consists of five dual-band antennas and a customized circuit that approximates lower- and higher-frequency phase difference. The main components of the customized circuit are down-conversion mixers and a phase detector module. For comparison, simulations were initially carried out using single- (1 GHz) and dual-frequency (1 GHz/2.3 GHz) sensor systems, and results indicated lower accuracy in classification of thick rind fruits of the single-frequency scheme. As a result, a dual-frequency sensor prototype was fabricated and experimented with normal and granulated plastic pomelo models and real pomelo fruits. The experimental results revealed that the average Φ{12} of the normal and granulated pomelos are almost identical, while the standard deviation (SD) of Φ 12 of the granulated pomelo is significantly larger than the normal pomelo. SD is thus used as the determinant of pomelo quality. The multibeam 1-GHz/2.3-GHz dual-frequency sensor system efficiently differentiates between normal and granulated pomelo fruits. As such, the proposed sensor system is operationally appropriate for quality control of thick rind fruits.
Some of the metrics are blocked by your
consent settings
Measurement of Radiated Field from Transmitting Antennas Located in Various Environments
(2019-04-01)
Krairiksh, Monai
;
Kittiyanpunya, Chainarong
;
Limpiti, Thunyawat
;
Tantisopharak, Tanawut
;
Leekul, Prapan
In microcellular communications, the transmitting antennas can be installed at low heights above the ground. However, even for low elevation towers, installation cost is still high. One of the possible ways for the deployment of base station antennas is to install them near the ground in order to do away with the tower. The main purpose of this paper is to suggest installation of the radiating antennas near the ground and tilting their orientation toward the sky - a totally nonintuitive solution. It will be shown that such deployments have the potential of reducing slow fading and can further enhance the signal strength close to the radiating antenna. This paper provides measured data for the received fields to validate the theoretical conjecture of such a deployment in various environments. The measured results are presented for 245, 800, 1000, and 2400 MHz. It is illustrated that such an unorthodox deployment can result in a low cost for the installation of base station antenna as the towers are not necessary. This can be useful in restoring communications in emergency situations where minimum infrastructure exists.
Some of the metrics are blocked by your
consent settings
Dual-band unidirectional cross dipole antenna
(2017-10-06)
Kittiyanpunya, Chainarong
;
Krairiksh, Monai
This paper presents a dual-band unidirectional antenna based on a straight dipole shunted with a meander line dipole antenna. This antenna is fed with a wide band Balun and equipped with reflectors to generate unidirectional patterns. The low and high frequency reflectors are plane and box reflectors, respectively. The antenna is well matched at the designed frequencies of 1 and 2 GHz. The unidirectional patterns are obtained at both frequencies with gain higher than 5.7 dBi. This antenna is used for illuminating microwave signal to an object under-Test in a dual-band reflectometer.
Some of the metrics are blocked by your
consent settings
Dual-band conical-scanning Yagi-Uda antenna
(2017-10-18)
Kittiyanpunya, Chainarong
;
Krairiksh, Monai
A dual-band conical-scanning Yagi-Uda antenna is presented. The proposed antenna is composed of dual-band director elements, dual-band driven elements, and planar reflectors which the alignment of each element is not on the same plane of the dual-band driven elements. The PIN diodes are used in order to change position of driven elements and directors. The patterns can be switched in four directions that main beams are in the zenith angle of 30°. It is shown that the dual-band antenna for 1 and 2 GHz operation achieves an impedance bandwidth of 8.5% and 12.5%, respectively. The front-to-back ratio of conical beams is higher than 8 dB. The antenna gain is around 6 dBi.
Some of the metrics are blocked by your
consent settings
Beam-Scanning Reflectometer for Detecting Granulated Fruits
(2017-03-01)
Kittiyanpunya, Chainarong
;
Leekul, Prapan
;
Phongcharoenpanich, Chuwong
;
Krairiksh, Monai
The problem of granulation in fruits costs vendors a big chunk of their revenue, hence a non-destructive sensor that can identify granulated fruits without destroying good fruits is highly desirable. This paper presents such a sensor system based on beam-scanning reflectometer operating at 2.45 GHz. Beams of scattered waves from several directions around the fruit are reflected by a conical reflector and scanned by a phased array of pattern reconfigurable Yagi-Uda antennas equipped with 1-b phase shifters for lowest loss in feed network. The collected data are used to calculate the Rician k-factor. The system was tested with plasticine spheres and real tangerines. It was found that the system with an eight-beam array was better than one with a four-beam array. This system may prove useful for quality control of tangerines and other agricultural products.
Some of the metrics are blocked by your
consent settings
Phased array of switched beam elements and application
(2017-01-17)
Kittiyanpunya, Chainarong
;
Krairiksh, Monai
This paper presents a two-element phased array antenna. The phase shifter for each element has one bit and each element has four beam directions. The suitable distance between elements provides side lobe level of less than -10 dB and gain higher than 6.3 dBi. With this simple configuration, this array antenna is useful in modern wireless communications and sensing applications.
Some of the metrics are blocked by your
consent settings
A reflectometer with beam switching capability
(2016-01-06)
Kittiyanpunya, Chainarong
;
Krairiksh, Monai
This paper presents a reflectometer using pattern reconfigurable antenna. A system based on the free-space technique is developed for measuring reflected wave from a material under test. The pattern reconfigurable antenna can be implemented through alteration of switches (On/Off). The proposed antenna is capable of re-directing the main beam toward intended material. It is able to minimize installation cost. The experiments were performed on a conductor plate, paper with different moisture content. The obvious different results show the usefulness in quality control of the product in industrial processes.
Some of the metrics are blocked by your
consent settings
Design of pattern reconfigurable printed Yagi-Uda antenna
(2016-01-01)
Kittiyanpunya, Chainarong
;
Krairiksh, Monai
This paper presents a pattern reconfigurable Yagi-Uda antenna on an FR-4 printed circuit board (PCB) for 2.435.2.465 GHzfrequency short-range radiocommunication devices. To realize the antenna, pin diodes are attached onto the antenna's driven elements and parasitic elements. The direction of the beam is shifted by alternating the pin diodes status between ON and OFF to induce a quad-directional operation so that E-plane maximum beams are formed in the directions of 135°, 45°, 310° and 225° (i.e. regions 1, 2, 3, 4), respectively. A series of simulations are performed on four parameters: microstrip-to-CPS (coplanar stripline), inter-parasitic spacing, parasitic length, and modes of parasitic elements (i.e. director/reflector) to determine the optimal antenna design. A prototype is fabricated based on the optimal simulation results. The experiments showed very good agreement between the simulation and measured results with regard to the reflection coefficients, radiation patterns and gains for all four beams. key words: pattern
Some of the metrics are blocked by your
consent settings
Pattern reconfigurable printed Yagi-Uda antenna
(2015-01-28)
Kittiyanpunya, Chainarong
;
Krairiksh, Monai
This paper presents a pattern reconfigurable antenna which is based on Yagi-Uda dipole antenna. The antenna can operate at ISM band of 2.45 GHz. It consists of microstrip-to-coplanar stripline (CPS) transition, driven elements and parasitic elements. The switch of driven element can be controlled by using PIN diodes while parasitic element function can be either reflector or director with different PIN diode states. The maximum of radiation patterns are in azimuth plane with four directions around the antenna to the directions of O = 40°, 120°, 220° and 320°.

KMITL

Browse

Filters

Settings

Sort By

Results per page

Search Results