Integrated active microstrip antenna for communication and identification applications

An integrated microstrip active antenna to be used in a miniature microwave transponder for communication and identification purposes is described. This active antenna, operating at 9.9 GHz, has a two layer structure and consists of a compact microstrip array antenna and a DPSK modulator/ASK demodulator. The radiating part of the active antenna is composed of electromagnetically fed, gap-coupled resonators which provide a good trade-off between performance and size reduction. The microwave circuit contains a single semiconductor component, a "cold" GaAs MESFET, which performs both the modulator and demodulator functions. The novel methods used to realize the active antenna provide high performance, size reduction, low power consumption and low cost which are major considerations in the design of microwave transponders.