ATSAM4S-WPIR-RD Atmel, ATSAM4S-WPIR-RD Datasheet - Page 26

• Manufacturer Part Number: ATSAM4S-WPIR-RD
• Description: Development Boards & Kits - ARM SAM4S16 W.PIR CAMERA REF. DESIGN
• Manufacturer: Atmel

Specifications of ATSAM4S-WPIR-RD

• Rohs: yes
• Product: Reference Designs
• Tool Is For Evaluation Of: ATSAM3S4BA
• Core: ARM Cortex M3
• Interface Type: JTAG, USB
• Operating Supply Voltage: 5 V
• Data Bus Width: 32 bit
• For Use With: RF231USB-RD

Figure 5-11. S11 and Smith diagram of unmatched antenna.
This measurement results in a matching network consisting of L2 = 1.5nH and L3 = 2.2nH. The second measurement
shows a resonance frequency which is about 50MHz higher than the aimed center frequency of 2.45GHz
(Figure
5-12).
Figure 5-12. S11 and Smith diagram of matched antenna.
If the custom application environment meets the environment used during the measurements, the channel dependency
of the radiated power can be noticeable. That means that working in channel 20 to 26 may result in a higher transmit
and receive range than working in channel 11 to 20.
5.4.2
Range measurement
The resonance behavior of the ceramic antenna itself gives no information about the antenna radiation. One available
test option is a range measurement. A good test site is a wide area free of trees and buildings. Compared to an
anechoic chamber, the chamber allows quantifiable antenna performance values. But a real (industrial) environment
may have quite different results of antenna performance because of undefined walls, machines, humans and other
interfering objects in the vicinity. The effect of multipath fading must not be underestimated.
In this case, the range test was performed with a firmware testing the packet error rate. The maximum transmit range is
defined by a packet error rate of 1%, that means if 100 packets failed during a transmit test of 10,000 packets the test
will be stopped and the maximum distance is reached. The needed hardware consists of two battery powered laptops
with side mounted USB sockets where the USB sticks are plugged. Each laptop is placed on the top of a tripod with a
height of 1.40 meters.
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Atmel AVR2030: ATRF231USB – Hardware User Manual [APPLICATION NOTE]
42018A−AVR−08/2012