4. Conclusion
This study designed a new UHF RFID reader
circular polarization antenna, aiming at improved
reception. In order to recognize several tags
simultaneously without errors in the distance, the
antenna was designed to separate the original signal
into two signals with phase difference of 90o
using
Hybrid coupler ( insert loss : 0.6dB) and provide each
of them for the two stripline antenna with a length of
λ/2 . And to realize the circular polarization wave
using the two signals with phase difference of 90o
, it
added the radiation plate with two feed points ( cross
section : 13.4cm2
), which contributed to
maximization of antenna radiation efficiency. The
size of the existing antenna about 21cm2
while that of
the antenna designed in this study was 13.4cm2
, about
half.