User's Manual

Table Of Contents

MRF89XAM9A

2.3 PCB Antenna

The PCB antenna is fabricated on the top copper trace.

Figure 2-11 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 by following the

recommendations in Section 1.2, Mounting Details.

The PCB antenna was designed and simulated using

Ansoft Designer

and HFSS™ 3D full-wave solver

software by ANSYS, Inc. (www.ansoft.com). The

design goal was to create a compact, low-cost antenna

with the best radiation pattern. Figure 2-11 shows the

simulation drawing and Figure 2-12 and Figure 2-13

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 2-14 shows the impedance simulation

and Figure 2-15 shows the actual impedance

measurement. The discrete matching circuitry matches

the impedance of the antenna with the SAW filter and

MRF89XA transceiver IC.

FIGURE 2-10: PCB ANTENNA

DIMENSIONS

FIGURE 2-11: PCB ANTENNA SIMULATION DRAWING

16.8mm

1.0mm

8.4mm

1.1mm

0.5mm

2.5mm