Ignatius Agung Wibowo

Control systems of a turntable and antenna positioning device in an open area test site

An open area test site (OATS) is a facility to measure radiated emissions of an electrical or electronic equipment in order to comply electromagnetic compatibility (EMC) requirements. In the measurement, the equipment under test (EUT) is placed in a turntable and the electromagnetic field radiated by the EUT is scanned using an antenna attached to a mast. The maximum radiation from the EUT is captured by rotating the turntable and vertically moving the antenna. This paper describes the development of the control systems of the scale models of a turntable and antenna positioning device. Stepper motor and dc motor are used to drive the turntable and antenna positioning device respectively. The motors are controlled by using microcontrollers. Speed and position control systems for both devices have been designed and the accuracies of the systems have been analyzed.

The application of wire mesh ground plane in Open Area Test Site for radiated emission measurement

Nowadays, the manufacturers apply the radiated emission test for all of their electrical or electronic products in order to avoid disturbance to other electrical or electronic products and to fulfil national or international standards. An Open Area Test Site (OATS) is one of the facilities used in the radiated emission measurement which requires the equipment under test (EUT), a receiving antenna with the antenna mast, the ground plane, and the radiated emission measurement device. The focus of this research is mainly about the ground plane of the OATS which can reflect the emission from the EUT to the receiving antenna. The perfect ground plane is very expensive; therefore the wire mesh ground plane can be used to cut the cost. The investigation of the ground plane could lead to an applicable radiated emission test and the accuracy of the measurement by using the mesh ground plane in OATS. In solving the problems related to the ground plane, the measurement of Normalized Site Attenuation (NSA) will be compared with the theoretical NSA. NSA is measured by transmitting signal from the frequency of 30 Mega Hertz (MHz) until 1000 MHz, assuming only two waves propagation which are direct wave and reflected wave.

Microcontroller Based Retail Pharmaceutical Tablets Counting Device

Unlike the tablets counter in the market, the product developed in this project is a portable tablets counter based on microcontroller PIC16F877A as the main controller. It could overcome the disadvantages of current counters in the market that are expensive, bulky and overly heavy. This project involved both hardware (mechanical and electrical) and software design. The programming was written in assembly language with MPLAB. Special vibration plate was designed to automatically load the tablets into the photo-detector channel individually. The visual indicator of the counting result is output to a 7-segment counter. The user could stop, start and reset the counting device easily. The counting accuracy is up to 100% for many shapes of pills ranged from 8 mm to 18 mm. Besides that, the programming has reduced the cost of customization, control external components speedily and counts up to 999 tablets.

Study on the application of wire mesh ground plane to an open-field antenna test site

This paper presents the preliminary result of a study on the application of wire mesh ground plane to an open-field antenna test site. Normalized site attenuation (NSA) measurements in the frequency of 30MHz till 1GHz for various conditions such as with and without ground plane, indoor and outdoor, and near to metal structures have been performed. The results are then compared and analyzed. It is shown that the wire mesh ground plane has a high potential to give an NSA within allowable range specified by the regulation for an open field antenna test site at the frequency of interest. Mesh ground plane is selected to be used for the test site due to practical and economical reasons.