Linx Technologies MDEV-900-HP3-xxx - Manual (Page 5)

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The Antenna Factor division of Linx offers
a diverse array of antenna styles, many of
which are optimized for use with our RF
modules. From innovative embeddable
antennas to low-cost whips, domes to
Yagis, and even GPS, Antenna Factor
likely has an antenna for you, or can
design one to meet your requirements.
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match for our modules and antennas. Connector City
focuses on high-volume OEM requirements, which
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MASTER DEVELOPMENT SOFTWARE
The development system is supplied
with Windows-based software that
facilitates communication with the
development boards through the Host
Interface Module. This software allows
for testing and illustrates basic
implementation of the modules as a
wireless serial link. The user selects
either a USB or RS232 connection and
whether the connected board is the
transmitter or receiver. The user can
then send text, ASCII characters, and even a picture. Documentation for the
software may be found by going to the 'Help' menu then 'Help File'.
Terminal emulation programs, such as HyperTerminal, do not provide error
correction; therefore, bit errors or data line hashing will be displayed as random
characters. Some form of error detection should be employed when developing
a protocol for wireless environments (please see Application Note AN-00160).
USING THE BOARDS AS A DESIGN REFERENCE
The master development boards included in this kit are very simple, yet they
illustrate some important techniques that you may wish to incorporate into your
own board layout. You will observe that the HP3 mounting pads (SMD version)
extend slightly past the edge of the part. This eases hand assembly and allows
for better heat conduction under the part if rework is necessary. Next, observe
the use of a full ground plane fill on the lower side of the board. This ground
plane serves three important purposes:
First, since a 1/4-wave antenna is employed, the ground plane is critical to serve
as a counterpoise (you may wish to read Application Note AN-00500 Antennas:
Design, Application, and Performance for additional details on how a ground
plane affects antenna function).
Second, a ground plane will suppress the transfer of noise between stages of a
product, as well as unintentional radiation of noise into free space.
Third, a ground plane allows for the implementation of a microstrip feed to the
antenna. The term microstrip refers to a PCB trace running over a ground plane
that is designed to serve as a 50-ohm transmission line between the module and
the antenna. A microstrip is implemented on this evaluation board. If you are
unfamiliar with microstrip calculations, you may wish to refer to the HP3 Series
Data Guides or the calculator available on the Linx Technologies website.
ABOUT ANTENNAS
The choice of antennas is one of the most critical and often overlooked design
considerations. The range, performance, and legality of an RF link are critically
dependent upon the type of antenna employed. Linx offers a variety of antenna
styles that you may wish to consider for your design. Included with your kit is a
Linx CW Series connectorized whip antenna that should be connected prior to
using the kit. Despite the fact that the antenna is not centered on the board’s
ground plane, it exhibits a VSWR of <1.7 and suitably demonstrates the
module’s best practical performance.
Figure 7: Master Development Software