Design Note
DN0007
2.4 GHz Inverted F Antenna
By Audun Andersen
Keywords
• CC2400
• CC2420
• CC2430
• CC2431
• CC2500
• CC2510
• CC2511
• CC2550
• CC2520
• CC2480
• PCB Antenna
• 2.4 GHz
• Inverted F Antenna
1 Introduction
This document describes a PCB antenna
design that can be used with all 2.4 GHz
transceivers and transmitters from Texas
Instruments. Maximum gain is measured
to be +3.3 dB and overall size
requirements for this antenna are 25.7 x
7.5 mm. Thus, this is a compact, low cost
and high performance antenna.
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Design Note
DN0007
Table of Contents
KEYWORDS.............................................................................................................................. 1
1 INTRODUCTION............................................................................................................. 1
2 ABBREVIATIONS........................................................................................................... 2
3 DESCRIPTION OF THE INVERTED F ANTENNA DESIGN ......................................... 3
3.1 IMPLEMENTATION OF THE INVERTED F ANTENNA.......................................................... 3
4 RESULTS........................................................................................................................ 4
4.1 RADIATION PATTERN.................................................................................................. 4
4.2 REFLECTION ............................................................................................................ 11
4.3 BANDWIDTH............................................................................................................. 11
5 CONCLUSION .............................................................................................................. 12
6 REFERENCES.............................................................................................................. 13
7 GENERAL INFORMATION .......................................................................................... 14
7.1 DOCUMENT HISTORY................................................................................................ 14
2 Abbreviations
CC2480 Z-Accel ZigBee Processor
EM Evaluation Module
IFA Inverted F Antenna
ISM Industrial, Scientific, Medical
PCB Printed Circuit Board
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Design Note
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3 Description of the Inverted F Antenna Design
Since the impedance of the Inverted F Antenna is matched directly to 50 ohm no external
matching components are needed.
3.1 Implementation of the Inverted F Antenna
It is important to make an exact copy of the antenna dimensions to obtain optimum
performance. The easiest approach to implement the antenna in a PCB CAD tool is to import
the antenna layout from either a gerber or DXF file. Such files are included in CC2430DB
reference design [1]. The gerber file is called “Inverted_F_Antenna.spl” and the DXF file is
called “Inverted_F_Antenna.dxf”. If the antenna is implemented on a PCB that is wider than
the antenna it is important to avoid placing components or having a ground plane close to the
end points of the antenna. If the CAD tool being used doesn’t support import of gerber or DXF
files, Figure 1 and Table 1 can be used.
Figure 1. IFA Dimensions
H1 5.70 mm W2 0.46 mm
H2 0.74 mm L1 25.58 mm
H3 1.29 mm L2 16.40 mm
H4 2.21 mm L3 2.18 mm
H5 0.66 mm L4 4.80 mm
H6 1.21 mm L5 1.00 mm
H7 0.80 mm L6 1.00 mm
H8 1.80 mm L7 3.20 mm
H9 0.61 mm L8 0.45 mm
W1 1.21 mm
Table 1. IFA Dimensions
Since there is no ground plane beneath the antenna, PCB thickness will have little effect on
the performance. The results presented in this design note are based on an antenna
implemented on a PCB with 1 mm thickness.
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Design Note
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4 Results
All results presented in this chapter are based on measurements performed with CC2430DB
[1].
4.1 Radiation Pattern
Figure 2 shows how to relate all the radiation patterns to the orientation of the antenna. The
radiation patterns were measured with CC2430 programmed to 0 dBm output power.
XY plane
XZ plane
YZ plane
Figure 2. How to Relate the Antenna to the Radiation Patterns
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Design Note
DN0007
Figure 3. XY Plane Vertical Polarization
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