User's Manual

B
UtiliNet SCADA Single Board Radio 98-1546 Rev AA 39
On-Board Antenna
On-Board Antenna Specifications
The On-Board antenna design is an F-antenna. This design was chosen because its performance is
more broad-band relative to a slot antenna, and its pattern is somewhat Omni-directional. This
antenna's maximum gain is 0 dB and its efficiency is 45%. This version of the product does not allow
an external antenna in conjunction to the on-board antenna.
Using the On-Board antenna, the recommended placement of the radio board is at the edge of the
OEM board, with the antenna-side edge of the board extending beyond the edge of the board,
hanging out in free space and facing up as shown below in Figure 1 - 8. If the antenna on the board
does not extend out in free space, then the customer's board will load the antenna and affect the
radiation pattern.
Also, an RF-transparent enclosure must be used (plastic or similar). Do not enclose the board within
a metal box. If a metal box is required to house the assembly, then the external antenna version of the
product should be considered.
The on-board F-antenna's radiation pattern in free space is nearly Omni-directional, but has nulls in
the direction of the 14-pin I/O connector. The best way to visualize the antenna's radiation pattern is
a semi-sphere about the antenna-side edge of the board.
The main radiating element is the long trace running the length of the board. The length of this trace
sets the resonant frequency of the antenna. The thicker F element, parallel to the feed element, is the
return path to ground. The length of the feed element and size of the gap between the feed and
ground elements dictate the match of the antenna.
Figure B - 1. Recommended Board Orientation for Optimal Antenna Performance
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