Compact and easy antenna with reflector for 2.4-GHz applications

Antennas for IoT terminals need to have a compact design to permit mobility and must be easy to manufacture to ensure high productivity and low cost. It is also desirable to reduce the influence of metals near the antenna, i.e., to make it unidirectional to enable ease of installation. The 'COSY' antenna was developed to meet these three requirements. It consists of a radiator and a reflector. The radiator has a simple configuration that consists of a plate element and a linear element and operates at the desired frequency by coupling with a reflector. This configuration suppresses any reduction in radiation resistance. The conventional type has a two-component configuration comprising a copper foil on FR-4 substrate for the radiator and a thin copper plate for the reflector. This paper first considers a simpler integrated model in which the radiator and reflector are formed from copper foil on both sides of a FR-4 board. Terminal antennas need to achieve a broadband configuration in addition to being compact in size. Therefore, after this section, a broadband model using dual-resonant matching with a parasitic element will be discussed.