Programmable Multifunctional RF/Microwave Circuit for Antenna and Filter Operation

This paper describes a multifunctional microwave device that can be reconfigured to behave either as a filter or an antenna. The device is based around a single-resonant element, referred to as a building block element that is connected to four ports. The resonant element is a microstrip square patch working in the 2.45 GHz unlicensed Industrial Scientific and Medical band used for IEEE 802.11 WiFi. The proposed building block is simple in its design and construction. This paper also presents devices composed of three building blocks, which can realize more complex filtering and antenna mode performance. In addition, p-i-n diodes have also been incorporated into the devices in order to facilitate electronic control. Measured results, pertaining to fabricated prototypes, show that filter and antenna operation can be achieved in the same device at a frequency of around 2.45 GHz with acceptable insertion loss and efficiency. In the future, it is anticipated that this could lead to a new paradigm, namely, a device that is analogous to a field programmable gate array operating in the microwave frequency regime.