Antenna and Propagation

Transcription

1 Antenna and Propagation This courseware product contains scholarly and technical information and is protected by copyright laws and international treaties. No part of this publication may be reproduced by any means, be it transmitted, transcribed, photocopied, stored in a retrieval system, or translated into any language in any form, without the prior written permission of Acehub Vista Sdn. Bhd. The use of the courseware product and all other products developed and/or distributed by Acehub Vista Sdn. Bhd. are subject to the applicable License Agreement. For further information, see the Courseware Product License Agreement. Objectives i) To familiarize with the ME1300 transmitter and receiver modules ii) To learn the usage of different antennas iii) To measure and plot antenna radiation patterns Equipment Required i) ME1300 Training Kit ii) RF Signal Generator (recommended model: Agilent N9310A) iii) A pair of monopole antennas iv) A pair of dipole antennas v) Accessories Required i) 1 x 5 V power adapter ii) 1 x Type A-to-Type B USB cable iii) 2 x SMA(m)-to-SMA(m) RF coaxial cable iv) A PC running Microsoft Windows 2000/XP/Vista with a minimum of 1 GB RAM, and preinstalled with setup prerequisites and the RadPat software (Refer to the ME1300 Quick Start Guide for the installation procedures) 1. Introduction The ME1300 training kit consists of a transmitter module (TX), a receiver module (RX), and a set of antennas. Together with the RadPat software, it can be used to measure antenna parameters using the built-in RF detector. Figure 1 shows the ME1300 training kit and a block diagram of the process flow, while Figure 2 shows the RadPat graphical user interface. ME1300 Antenna and Propagation Lab 1-1/16

2 Transmitting Antenna Receiving Antenna RadPat PC Software External RF Signal Generator Antennas Set Transmitter Module Transmitting Antenna Transmits RF signal RF Signal Receiving Antenna (AUT-Antenna Under Test) Receives RF signal and rotates the antenna module Receiver Module RF Signal Generator Generates RF signal Communicates with the controls the rotator, and collects and processes data RadPat Software Figure 1 ME1300 Training Kit and Process Flow Block Diagram ME1300 Antenna and Propagation Lab 1-2/16

3 Figure 2 RadPat Graphical User Interface The graphical user interface of the RadPat software consists of the following features: 1. Rotator control tab 2. Settings tab 3. Rotator measurement results display panel 4. Antenna radiation pattern polar chart 5. Status bar The RadPat software is a tool to communicate with the RF detector. The RadPat software is capable of rotating the receiver module antenna and displaying the antenna angular position. It allows the configuration of serial communications, and detects serial communication errors. It is also capable of collecting measurement data from the RF detector and displaying the data in a list, as well as plotting the antenna radiation pattern on the polar chart. ME1300 Antenna and Propagation Lab 1-3/16

4 2. RadPat Software Configuration 1. The RadPat software communicates with the receiver module and the RF detector. 2. Open the RadPat software; click Settings at the menu bar, and select ComPort. The dialog box as shown in Figure 3 appears. 3. In the ComPort tab, select the desired PC ComPort and make sure that the selected PC ComPort matches the one set earlier for the PC. 4. Set the Baud Rate to You may click the Check ComPort Connection button to verify the COM port connection of the PC. Figure 3 ComPort Settings Tab 5. Click the Instrument tab and unselect Enable Instrument. The RF detector will be activated when the Enable Instrument is unselected. Figure 4 Instrument Settings Tab ME1300 Antenna and Propagation Lab 1-4/16

5 6. In the RF signal generator, set Frequency to 915 MHz. This is the frequency of the antennaunder-test (AUT). 7. Set RF signal generator Power Level to 5 dbm. 8. Click the Measurement tab. This allows you to change the measurement parameters as shown in Figure 5. Figure 5 Measurement Settings Tab 9. Deg/Step in the Rotator panel defines the turning angle of the rotator. The program will observe and record the data for every step position defined in Deg/Step. The minimum and maximum values are 5 degrees and 30 degrees respectively. By default, Deg/Step is set to Radiation Pattern Plot defines the 0-dB reference value for the radiation pattern. By default, it is set to 20 dbm. 11. Scale lets you adjust the resolution of the radiation pattern on the polar chart. Set the resolution to 15 db/div. 12. Click Connect after configuring all the desired parameters. This will bring the rotator back to its home position. 13. The Info Display tab shows the information of the configured parameters and the operations of RadPat. Figure 6 Info Display Tab ME1300 Antenna and Propagation Lab 1-5/16

6 14. After the homing operation has completed, the window will return to the RadPat main interface. Click Run at the menu bar to perform the Start, Pause, Stop, and Homing operations of the rotator. 15. Click Graph at menu bar to Normalize or Undo the normalization of the radiation pattern. 16. RadPat allows you to save the plotted data and display the data when necessary, as shown in Figure 8. To save the data, click File at the menu bar, and then click Save As. Select the desired directory to save the plotted data. To recall the saved data, click File at the menu bar, and then click Open. Select the corresponding directory to retrieve the data. Figure 7 Show Recorded Data Display 17. You may click a particular plotted data in the DATA POINT panel. The selected point in the radiation pattern will be indicated as a red circle. ME1300 Antenna and Propagation Lab 1-6/16

7 3. Antenna Radiation Pattern Measurement 3.1 Using the 915 MHz Dipole Antennas Note: To get the best accuracy, you should perform calibration before making any measurements on your RF detector. Please refer to Appendix C for the calibration procedure. Figure 8 Equipment Setup 1. Set up the equipment as shown in Figure MHz 2 dipole antennas are used for the measurement. Mount the dipole antenna on the top connector of the fixed antenna holder on the transmitter module (TX). This is the transmitting antenna. Orientate the antenna for H-Plane radiation and broadside to the other antenna-undertest (AUT). 3. Use an RF coaxial cable to connect the RF OUT connector of an RF signal generator to the RF IN connector of the transmitter module (TX). 4. Mount the other 915 MHz dipole antenna (AUT) on the top connector of the rotatable antenna holder on the receiver module (RX). This is the receiving antenna. Orientate the receiving antenna broadside to the transmitting antenna as shown in Figure 9 for H-plane radiation and maximum reception. TX AUT (RX) Figure 9 Orientation of Receiving and Transmitting Antennas for H-Plane radiation ME1300 Antenna and Propagation Lab 1-7/16

8 5. Connect the RF IN connector and RF OUT connector on the receiver module (RX) using a coaxial cable (to send the signal back to the RF detector). 6. Adjust the distance between the antennas to 50 cm and make sure that they are in the far-field region. Record the distance and the heights of the antennas in the corresponding record form as given in Appendix A. 7. Open the RadPat software and select the desired PC ComPort under Settings > ComPort tab. 8. Set Baud Rate to under Settings > ComPort tab. Click the Instrument tab and unselect Enable Instrument. The RF detector will be activated when the Enable Instrument is unselected. 9. In the RF signal generator, set Frequency to 915 MHz. This is the frequency of the antennaunder-test (AUT). 10. Set RF signal generator Power Level to 5 dbm. 11. Click the Measurement tab and set Deg/Step to 10, 0-dB Ref: to 20 dbm, and Scale to 10 db/div. 12. Click Connect to bring the rotator back to its home position. 13. After the homing operation, the window will return to the RadPat main interface. Click Run at the menu bar to perform the Start, Pause, Stop, and Homing operations of the rotator. 14. Click Run at the menu bar followed by Start to begin the antenna radiation pattern plotting. 15. Observe the plotting and record the received signal strength at each step (e.g., 10 ) in the corresponding record form as given in Appendix A. 16. Determine the value of max P R, based on the radiation pattern plotting and calculate the Normalized (db) value for each step. 3.2 Using the 2.4 GHz Dipole Antennas 1. Repeat all steps of section Using the Dipole Antenna with 915 MHz and 2.4 GHz 1. Repeat all steps of section Using the Dipole Antenna with 915 MHz and Monopole Antenna with 915 MHz 1. Repeat all steps of section 3.1 ME1300 Antenna and Propagation Lab 1-8/16

9 4. Discussions 1. Explain the difference between the data collected from all experiments Antenna Rotation Measurement Using RF Detector Record Form Table MHz Dipole Antennas Angle (Degree) RF Level (dbm) Angle (Degree) RF Level (dbm) Table GHz Dipole Antennas Angle (Degree) RF Level (dbm) Angle (Degree) RF Level (dbm) ME1300 Antenna and Propagation Lab 1-9/16

10 Table 3.3 Dipole Antenna with 915 MHz and 2.4 GHz Angle (Degree) RF Level (dbm) Angle (Degree) RF Level (dbm) Table Dipole Antenna with 915 MHz and Monopole Antenna with 915 MHz Angle (Degree) RF Level (dbm) Angle (Degree) RF Level (dbm) ME1300 Antenna and Propagation Lab 1-10/16

11 Polar Chart Polar Chart ME1300 Antenna and Propagation Lab 1-11/16

12 Polar Chart Polar Chart ME1300 Antenna and Propagation Lab 1-12/16

13 Tips on How to Calibrate the RF Detector 1. Setup the equipment as shown in Figure 10. To connect the two rods, remove one SMA adapter from one of the rod. This setup is with the assumption that removing the SMA adapter has insignificant impact on this calibration process.. Figure 10 Calibration Setup 2. In Radpat, click on the Calibration at the Settings menu bar. At the calibration tab, click on Perform Calibration button to run the calibration. Figure 11 Calibration Menu Tab 3. At the calibration window, key in the value of the desired frequency. ME1300 Antenna and Propagation Lab 1-13/16

14 4. At the signal generator, set the power level of the signal generator according to the calibration points which stated at the calibration table. For example -60 dbm. Then press the RF On button at the signal generator to turn on the RF Output. 5. At first, the measured value might be fluctuating a lot. Wait until the measured value settling down with minimum fluctuation, and then press the SET button to set the calibrated value. Figure 12 Calibration Window 6. Repeat step 4 and 5 for the other power levels. Save the calibrated data after ALL the calibration points were calibrated. 7. Save the calibration file with the desired name at the desired location (Calibration folder is suggested). 8. Make sure the calibration file is loaded before making any measurements on your RF detector. ME1300 Antenna and Propagation Lab 1-14/16

15 Appendix D Tips on How to Import the Plotted Data into Microsoft Excel The plotted data on RadPat is saved in the dat format (with the.dat extension) and can be opened by any text editor. For example, you may import the plotted data into Microsoft Excel to further analyze the data. 1. Open Microsoft Excel if it is not already opened. 2. Select the desired directory using the keyboard shortcut Ctrl+O. 3. In the Files of type: box, select All Files (*.*); select the text file that you wish to import into Microsoft Excel. This is shown in Figure 13. Figure 13 Opening the Import Text File 4. Click Open after selecting the desired text file. The following Text Import Wizard window appears. Figure 14 Text Import Wizard (Step 1) ME1300 Antenna and Propagation Lab 1-15/16

16 5. Select Delimited and set Start import at row: to 1. Leave the default setting for File origin:, and then click Next. 6. Select Comma under Delimiters as shown in Figure 15, and then click Next. Figure 15 Text Import Wizard (Step 2) 7. Select General. Click Finish to import the plotted data into Microsoft Excel. Figure 16 Text Import Wizard (Step 3) ME1300 Antenna and Propagation Lab 1-16/16