User Guide

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Table Of Contents

7 Design Guidelines

7 DESIGN GUIDELINES

7.1 Layout and Placement

For optimal performance of the LYRA S the following guidelines are recommended:

 Place the module 1.50 mm from the edge of the copper “keep-in” area at the middle of the long edge of the application

PCB, as illustrated in Figure 10.

 Copy the exact antenna design from Figure 10 with the values for coordinates A to L given in Figure 11.

 Make a cutout in all lower layers aligned with the right edge and the bottom edge of the antenna as indicated by the

yellow box in Figure 12.

 Connect all ground pads directly to a solid ground plane in the top layer.

 Connect RF_2G4 to ANT_IN through a 0-ohm resistor.

– The 0-ohm gives the ability to test conducted and to evaluate the antenna impedance in the design.

 Place ground vias as close to the ground pads of the LYRA S as possible.

 Place ground vias along the antenna loop right and bottom side.

 Place ground vias along the edges of the application board.

 Do not place plastic or any other dielectric material in contact with the antenna.

– A minimum clearance of 0.5 mm is advised.

– Solder mask, conformal coating and other thin dielectric layers are acceptable directly on top of the antenna region.

Figure 1: Recommended Layout for LYRA S

Summary of content (6 pages)

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A 7 DESIGN GUIDELINES 7.1 Layout and Placement For optimal performance of the LYRA S the following guidelines are recommended:          Place the module 1.50 mm from the edge of the copper “keep-in” area at the middle of the long edge of the application PCB, as illustrated in Figure 10. Copy the exact antenna design from Figure 10 with the values for coordinates A to L given in Figure 11.
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Lyra S Datasheet Figure 2: Antenna Layout With Coordinates Table 1: Antenna Polygon Coordinates, Referenced to Center of LYRA S Point LYRA SC22HNA2 A (2.87, 2.13) B (2.54, 2.13) C (2.54, 3.69) D (3.36, 4.51) E (7.75, 4.51) F (7.75, 4.15) G (6.84, 4.15) H (6.21, 3.52) I (4.26, 3.52) J (3.97, 3.81) K (3.10, 3.81) L (2.87, 3.58) Wloop 4.88 Hloop 4.15 Note: 1. All coordinates and dimensions listed in mm. https://www.lairdconnect.
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Lyra S Datasheet Figure 3: Antenna Clearance in Inner and Bottom Layers https://www.lairdconnect.
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Lyra S Datasheet 7.2 Best Design Practices The design of a good RF system relies on thoughtful placement and routing of the RF signals. The following guidelines are recommended:       Place the LYRA S and antenna close to the center of the longest edge of the application board. Do not place any circuitry between the board edge and the antenna. Make sure to tie all GND planes in the application board together with as many vias as can be fitted.
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Lyra S Datasheet Figure 5: Non-Optimal Layout Examples https://www.lairdconnect.
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Lyra S Datasheet 7.3 Radio Performance vs. Carrier Board Size For many applications, the carrier board size is determined by the overall form factor or size of the additional circuitry. The recommended carrier board width 55 mm for the LYRA S is thus not always possible in the end-application.