Microchip Technology TXRX Module 868 MHZ ULP SUB GHZ MRF89XAM8A-I/RM MRF89XAM8A-I/RM データシート

DS70651A-page 14

© 2010 Microchip Technology Inc.

The PCB antenna is fabricated on the top copper trace.

 illustrates 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 given in the 

.

The PCB antenna was designed and simulated using
Ansoft Designer

®

 and HFSS™ 3D full-wave solver

software by ANSYS Inc. (

www.ansoft.com

). The goal of

the design was to create a compact, low-cost antenna
with the best radiation pattern. 

 illustrates

the simulation drawing and 

 and

 illustrates the 2D and 3D radiation

patterns. As shown by the radiation patterns, the
performance of the antenna is dependant upon the
orientation of the module. 

 illustrates the

impedance simulation and 

 illustrates the

simulated PCB antenna VSWR. The discrete matching
circuitry matches the impedance of the antenna with
the SAW filter and MRF89XA transceiver IC.

Top Copper

Ground Plane

Power Plane

Bottom Copper

1/2 oz. Copper

1/2 oz. Copper

1/2 oz. Copper

1/2 oz. Copper

8 mil FR4

12 mil FR4

8 mil FR4

0.032”

± 0.005”

16.8mm

1.0mm

8.4mm

1.1mm

0.5mm

2.5mm