Integration Instructions

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FSS JODY-W263 Integration Instructions Rev 02.docx
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5.2.2 Antenna Design
Designers must take care of the antennas from all perspective at the very start of the
design phase when the physical dimensions of the application board are under
analysis/decision, since the RF compliance of the device integrating JODY-W2 module
with all the applicable required certification schemes heavily depends on antennas
radiating performance.
• External antennas such as linear monopole:
o External antennas basically do not imply physical restriction to the design
of the PCB where the module is mounted.
o The radiation performance mainly depends on the antennas. It is required
to select antennas with optimal radiating performance in the operating
bands.
o RF cables should be carefully selected with minimum insertion losses.
Additional insertion loss will be introduced by low quality or long cable.
Large insertion loss reduces radiation performance.
o A high quality 50 Ω coaxial connector provides proper PCB-to-RF-cable
transition.
• Integrated antennas such as patch-like antennas:
o Internal integrated antennas imply physical restriction to the PCB design:
▪ Integrated antenna excites RF currents on its counterpoise, typically the
PCB ground plane of the device that becomes part of the antenna; its
dimension defines the minimum frequency that can be radiated.
Therefore, the ground plane can be reduced down to a minimum size
that should be similar to the quarter of the wavelength of the minimum
frequency that has to be radiated, given that the orientation of the
ground plane related to the antenna element must be considered.
▪ The RF isolation between antennas in the system must be as high as
possible and the correlation between the 3D radiation patterns of the
two antennas has to be as low as possible.
▪ In general, an RF separation of at least a quarter wavelength between
the two antennas is required to achieve a minimum isolation and low
pattern correlation; increased separation should be considered, if
possible, to maximize the performance and fulfil the requirements in
Table 8.