EM2420 ETC [List of Unclassifed Manufacturers], EM2420 Datasheet - Page 62

• Manufacturer Part Number: EM2420
• Description: 2.4 GHz IEEE 802.15.4 / ZigBee RF Transceiver
• Manufacturer: ETC [List of Unclassifed Manufacturers]

Monopole
antennas with a length corresponding to
one quarter of the electrical wavelength
(λ/4). They are very easy to design and
can be implemented simply as a “piece of
wire” or even integrated into the PCB.
The length of the λ/4-monopole antenna is
given by:
where f is in MHz, giving the length in cm.
An antenna for 2450 MHz should be 2.9
cm.
Non-resonant monopole antennas shorter
than λ/4 can also be used, but at the
expense of range. In size and cost critical
applications such an antenna may very
well be integrated into the PCB.
Enclosing the antenna in high dielectric
constant material reduces the overall size
Ember Part Number: 120-0049-000C
antennas
L = 7125 / f
are
resonant
EM2420 Datasheet
of the antenna. Many vendors offer such
antennas intended for PCB mounting.
Helical antennas can be thought of as a
combination of a monopole and a loop
antenna. They are a good compromise in
size critical applications. Helical antennas
tend to be more difficult to optimize than
the simple monopole.
Loop antennas are easy to integrate into
the PCB, but are less effective due to
difficult impedance matching because of
their very low radiation resistance.
For low power applications the differential
antenna is recommended giving the best
range and because of its simplicity.
The antenna should be connected as
close as possible to the IC. If the antenna
is located away from the RF pins the
antenna should be matched to the feeding
transmission line (50 Ω).
EM2420
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