Abstract
This paper presents simulation and measurement results from a variety of
compact PCBbased antenna designs suitable for wireless systems operating
at 2.4 GHz using realistic implementation conditions in contrast to
idealized, best-case, configurations. In particular, the input
impedance, radiation pattern, and radiation efficiency were measured
using a variety of simulated and physically constructed prototypes and
test fixtures. The results were compared with published application
notes and manufacturer specifications to obtain better estimates of
antenna performance in implementations, such as centimeterscale wireless
sensor nodes with size and/or weight constraints. Notable deviations
from published expectations of performance were exhibited in both
simulation and measurement, including absolute gain, input impedance,
and radiation pattern. Reasonably high radiation efficiency was also
demonstrated. Significant deviations from both simulation and
manufacturer-published results were observed in all investigated
parameters. Differences from datasheet values of as much as 11 dB in
antenna match and 12 dBi in maximum gain are reported. These results
indicate a number of important considerations for a wireless sensor
system designer, including that chip antennas are highly preferable to
PCB trace antennas if cost is not a concern, implementations of designs
tend to decrease directivity, and as much as half the efficiency
expected from simulation is seen in realistic implementation.