Methods, systems, and apparatuses for RFID devices, such as reader
antennas, are described. A reader antenna includes a quadrature hybrid
coupler, a termination element, and an antenna, such as a patch antenna.
The quadrature hybrid coupler has first, second, third, and fourth ports.
The first port receives an input radio frequency RF signal. The second
port outputs a first RF output signal. The third port outputs a second RF
output signal. The second RF output signal is shifted in phase by 90
degrees relative to the first RF output signal. The fourth port is
coupled to the termination element. The patch antenna has a first point
coupled to the first RF output signal and a second point coupled to the
second RF output signal. The patch antenna radiates a circularly
polarized RF signal due to the received first and second RF output
signals. The circularly polarized RF signal may be used to interrogate
tags. Furthermore, the reader antenna is integrated into a ruggedized
structure that provides environmental protection for the antenna,
including providing shock absorption for impacts to the antenna.