Low-Cost Small-Antenna Measurement Tool Based on ATMega8535 Microcontroller

M. Ammar Wibisono, Achmad MunirTelecommunication EngineeringSchool of Electrical Engineering and InformaticsInstitut Teknologi Bandung, Indonesia

The 13th International Conference on Electronics, Information and Communication (ICEIC) 2013

Outline

Background Problem Definition Proposed Solution System Design System Implementation and Testing Result and Conclusion Demonstration Video Question & Answer Session

Background

Fabricated antenna needs to be measured to confirm that its parameters are matched with its simulation / theoretical result

Experiment in measuring antenna parameters such as radiation pattern, gain, directivity, input impedance, return loss, VSWR, etc. can help students to understand the antenna properties

Antenna radiation pattern measurement

A microstrip patch antenna at our lab and its measured radiation patternSpherical positioning system for

the antenna radiation pattern measurement

Outline

BackgroundProblem Definition Proposed Solution System Design System Implementation and Testing Result and Conclusion Demonstration Video Question & Answer Session

Problem Definition

The antenna measurement tools from some vendors are relatively expensive

The antenna measurement tool usually needs additional instruments (PC) and the software which made the system more complex

Outline

Background Problem DefinitionProposed Solution System Design System Implementation and Testing Result and Conclusion Demonstration Video Question & Answer Session

Proposed Solution

We build a simple, easy-to-use and low cost measurement tool for small antenna with ATMega8535 as the MCU, LCD and keypad as the user-interface, stepper motor as the actuator for the azimuth angle, and servo motor as the actuator for the elevation angle

Outline

Background Problem Definition Proposed SolutionSystem Design System Implementation and Testing Result and Conclusion Demonstration Video Question & Answer Session

System Design (Hardware)

Stepper and Servo motor control

- Servo motor position is controlled by using 5V PWM signal from OC1B pin with period of 20 ms-The angle position of the servo motor is directly proportional to the pulse width of the PWM signal (t)

-Stepper motor is rotated by alternating DC signal from 4 pins-L298 Dual H-Bridge IC is needed to drive the stepper motor-8 reverse-biased diodes are needed to suppress the back emf generated by the stepper motor coil

System Design (Software)

Sytem Design (Mechanical)

Outline

Background Problem Definition Proposed Solution System DesignSystem Implementation and

Testing Result and Conclusion Demonstration Video Question & Answer Session

System Implementation and Testing

Programming the MCU and testing the interface module & the servo motor

Testing the accuracy of the mechanical system

Load test by placing a small microstrip antenna

Outline

Background Problem Definition Proposed Solution System Design System Implementation and TestingResult and Conclusion Demonstration Video Question & Answer Session

Experimental Result

-The tool we made can work with resolution angle of 10

-The maximum deviation of azimuth angle is 10

-The maximum load that gives 2.50 deviation in elevation angle is about 100 grams

Budgeting

- Power Supply US$5- MCU Module US$10- Keypad US$5- LCD Display US$4- Servo Motor US$14- Stepper Motor US$25- Mechanical system US$45- Cables, connectors and box US$12

- Total US$120(without tripod)

Conclusion & Recommendation

The antenna measurement tool we made has relatively low cost, but has some limitations at the maximum load and the accuracy

To improve the maximum load and the accuracy, we can use a servo or stepper motor with higher maximum torque

Outline

Background Problem Definition Proposed Solution System Design System Implementation and Testing Result and ConclusionDemonstration Video Question & Answer Session

Demonstration Video

Question & Answer Session