APPLICATION NOTE
ATREB233-XPRO Antenna Performance Measurement
VSWR and Radiation Pattern Measurement Report
Features
•
•
VSWR (Voltage Standing Wave Ratio) Measurements
Antenna Radiation Patterns Measurements
42260A−AVR−04/2014
Table of Contents
1. Introduction ........................................................................................ 3
2. Configuration...................................................................................... 3
2.1
Hardware Configuration .................................................................................... 3
3. VSWR Measurement ......................................................................... 4
4. Radiation Pattern Measurement ......................................................... 5
4.1
4.2
Measurement Procedure ................................................................................... 5
Measurement Results ....................................................................................... 6
4.2.1
Channel 11 XY Plane.......................................................................... 6
4.2.2
Channel 11 XZ Plane .......................................................................... 6
4.2.3
Channel 11 YZ Plane .......................................................................... 7
4.2.4
Channel 18 XY Plane.......................................................................... 7
4.2.5
Channel 18 XZ Plane .......................................................................... 8
4.2.6
Channel 18 YZ Plane .......................................................................... 8
4.2.7
Channel 26 XY Plane.......................................................................... 9
4.2.8
Channel 26 XZ Plane .......................................................................... 9
4.2.9
Channel 26 YZ Plane ........................................................................ 10
5. Revision History ............................................................................... 11
ATREB233-XPRO Antenna Performance Measurement [APPLICATION NOTE]
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2
1.
Introduction
For a radio (transmitter or receiver) to deliver power to an antenna, the impedance of the radio and transmission line
must be well matched to the antenna's impedance. The parameter VSWR is a measure that numerically describes how
well the antenna is impedance matched to the radio or transmission line it is connected to.
The antenna radiation pattern is the display of the radiation properties of the antenna as a function of the spherical
coordinates. In most cases, the radiation pattern is determined in the Far-Field region for constant radial distance and
frequency. A typical radiation pattern is characterized by a main beam with 3dB beam width and side lobes at different
levels.
This document describes how the VSWR and radiation pattern measurements are conducted for the Atmel® REB233XPRO RF module.
2.
Configuration
2.1
Hardware Configuration
•
•
•
•
DUT: REB233-XPRO board
Network Analyzer and its accessories
Spectrum Analyzer and its accessories
Horn antenna with accessories
ATREB233-XPRO Antenna Performance Measurement [APPLICATION NOTE]
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3
3.
VSWR Measurement
In a radio frequency (RF) electrical transmission system, the standing wave ratio (SWR) is a measure of how efficiently
RF power is transmitted from the power source, through the transmission line, and into the load.
SWR is, thus, the ratio between transmitted and reflected waves. A high SWR indicates poor transmission-line
efficiency and reflected energy, which can damage the transmitter and decrease transmitter efficiency. Since SWR
commonly refers to the voltage ratio, it is usually known as voltage standing wave ratio (VSWR). Figure 3-1 shows the
VSWR measurements for REB233-XPRO Board.
S11 (Reflected power) for the REB233-XPRO Antenna port 1 is the least for the frequency close to 2.4GHz.
Figure 3-1. VSWR Measurement
ATREB233-XPRO Antenna Performance Measurement [APPLICATION NOTE]
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4
4.
Radiation Pattern Measurement
The radiation pattern measurement of the antenna is the graphical representation of the radiation properties of the
antenna. It describes that how the antenna radiates out or receives the energy into or from space. It is important to state
that an antenna radiates energy in all directions, at least to some extent, so the antenna pattern is actually threedimensional. These principal plane patterns can be obtained by making two slices through the 3D pattern through the
maximum value of the pattern or by direct measurement. It is these principal plane patterns that are commonly referred
to as the antenna patterns. So based on the orientation of the antenna, the patterns may differ and it should be helpful
in deciding the range of the antenna devices.
4.1
Measurement Procedure
1.
2.
3.
4.
5.
6.
The radiation pattern measurement is carried out for the PCB antenna present on the REB233-XPRO board.
The DUT is kept on 360° rotating table.
A Horn Antenna tuned to 2.4GHz, and connected to a Spectrum Analyzer is placed at an exact distance of 3m
from the DUT rotating table.
The Measurement is made inside an Anechoic Chamber.
Un-modulated Carrier at Channels 11, 18, and 26 is fed to the antenna with known power.
The radiated power out of the antenna is measured by a Horn receiving antenna. The DUT is kept in all three
planes as shown in Figure 4-1 and the readings are measured.
Figure 4-1. Rotational Orientation Diagram
Y
X
Z
XY Plane
XZ Plane
YZ Plane
ATREB233-XPRO Antenna Performance Measurement [APPLICATION NOTE]
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4.2
Measurement Results
4.2.1
Channel 11 XY Plane
Figure 4-2. Channel Low XY Plane
Field Strength (dBµv/m)
360
100
340
0
20
40
80
320
60
300
60
40
80
20
280
0
100
260
120
240
220
4.2.2
Field Strength (dBµv/m)
140
200
180
160
Channel 11 XZ Plane
Figure 4-3. Channel Low XZ Plane
Field Strength (dBµv/m)
360
100
340
80
320
60
300
40
20
280
0
0
20
40
60
80
100
260
Field Strength (dBµv/m)
120
240
220
140
200
180
160
ATREB233-XPRO Antenna Performance Measurement [APPLICATION NOTE]
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4.2.3
Channel 11 YZ Plane
Figure 4-4. Channel Low YZ Plane
Field Strength (dBµv/m)
360
100
340
0
20
40
80
320
60
300
60
40
80
20
280
Field Strength (dBµv/m)
0
100
260
120
240
140
220
200
4.2.4
180
160
Channel 18 XY Plane
Figure 4-5. Channel Mid XY Plane
Field Strength (dBµv/m)
340
360
100
0
20
40
80
320
60
300
60
40
80
20
280
0
100
260
Field Strength (dBµv/m)
120
240
140
220
200
180
160
ATREB233-XPRO Antenna Performance Measurement [APPLICATION NOTE]
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4.2.5
Channel 18 XZ Plane
Figure 4-6. Channel Mid XZ Plane
Field Strength (dBµv/m)
360
100
340
0
20
40
80
320
60
300
60
40
80
20
280
0
260
120
240
220
4.2.6
Field Strength (dBµv/m)
100
140
200
180
160
Channel 18 YZ Plane
Figure 4-7. Channel Mid YZ Plane
Field Strength (dBµv/m)
340
360
100
0
20
40
80
320
60
300
60
40
80
20
280
0
100
260
Field Strength (dBµv/m)
120
240
140
220
200
180
160
ATREB233-XPRO Antenna Performance Measurement [APPLICATION NOTE]
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4.2.7
Channel 26 XY Plane
Figure 4-8. Channel High XY Plane
Field Strength (dBµv/m)
360
100
340
0
20
40
80
320
60
300
60
40
80
20
280
0
100
260
120
240
140
220
200
4.2.8
Field Strength (dBµv/m)
180
160
Channel 26 XZ Plane
Figure 4-9. Channel High XZ Plane
Field Strength (dBµv/m)
340
360
100
0
20
40
80
320
60
300
60
40
80
20
280
0
100
260
Field Strength (dBµv/m)
120
240
220
140
200
180
160
ATREB233-XPRO Antenna Performance Measurement [APPLICATION NOTE]
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4.2.9
Channel 26 YZ Plane
Figure 4-10. Channel High YZ Plane
Field Strength (dBµv/m)
340
360
100
0
20
40
80
320
60
300
60
40
80
20
280
0
100
260
Field Strength (dBµv/m)
120
240
220
140
200
180
160
ATREB233-XPRO Antenna Performance Measurement [APPLICATION NOTE]
42260A−AVR−04/2014
10
5.
Revision History
Doc. Rev.
Date
Comments
42260A
04/2014
Initial document release
ATREB233-XPRO Antenna Performance Measurement [APPLICATION NOTE]
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11
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