MRF24J40MA Datasheet, PDF (16/30 Pages) Microchip Technology – 2.4 GHz IEEE Std. 802.15.4 RF Transceiver Module

MRF24J40MA
2.3 PCB Antenna
The PCB antenna is fabricated on the top copper trace.
Figure 2-8 shows the trace dimensions. The layers
below the antenna have no copper traces. The ground
and power planes under the components serve as a
counterpoise to the PCB antenna. Additional ground
plane on the host PCB will substantially enhance the
performance of the module. For best performance,
place the module on the host PCB following the
recommendations in Section 1.2 “Mounting Details”.
The Printed Circuit Board (PCB) antenna was designed
and simulated using Ansoft Designer^® and HFSS™ 3D
full-wave solver software by Ansoft Corporation
(www.ansoft.com). The design goal was to create a
compact, low-cost antenna with the best radiation
pattern. Figure 2-9 shows the simulation drawing and
Figure 2-10 and Figure 2-11 show the 2D and 3D
radiation patterns, respectively. As shown by the
radiation patterns, the performance of the antenna is
dependant upon the orientation of the module.
Figure 2-12 shows the impedance simulation and
Figure 2-13 shows the actual impedance measurement.
The discrete matching circuitry matches the impedance
of the antenna with the MRF24J40 transceiver IC.
FIGURE 2-8:
11.0 mm
PCB ANTENNA
DIMENSIONS
16.0 mm
4.0 mm
2.0 mm 2.5 mm
5.0 mm
FIGURE 2-9:
PCB ANTENNA SIMULATION DRAWING
Z
Y
X
DS70329A-page 14
Advance Information
© 2008 Microchip Technology Inc.