Reconfigurable narrowband antennas with operating frequency agility can provide several performance benefits like size compactness, improved noise performance, and suppression of out-of-band interferences. However, much of the research effort has focused on observing the hardware capabilities, and antenna reconfiguration is rarely implemented with a software-defined radio (SDR). The hardware/software modularity of an SDR testbed provides an opportunity to adapt the signal processing parameters along with the antenna configuration, enabling a test system capable of demonstrating/analyzing the performance impact of reconfigurable antennas on modulated data streams. Accordingly, we are developing an SDR-based platform to test the performance of tunable antennas in a modern communication environment.
From a hardware perspective, the antenna’s operating frequency is continuously tuned using piezoelectric linear actuator motors that vary the overall capacitive loading of the passive antenna. The linear actuators are controlled using external software, which converts the electrical signal to a mechanical movement of the actuator. As a preliminary step of testing the system, we are using the GNURadio software to automate the antenna’s tunability alongside a modulated data stream. In this paper, we will describe our efforts towards the co-configuration of a GNURadio OFDM signal processing flowgraph and the front-end antenna’s operating frequency, which also impacts the operating bandwidth. We will describe our test configuration and analysis of a 3-node system with Tx and Rx nodes using the reconfigurable antenna design and a third interfering node. The interfering node is set to generate various out-of-band signals that would negatively impact the primary link’s performance without proper anti-aliasing. This test setup will highlight the value of this narrowband filtering within the antenna structure in order to mitigate aliasing issues from the out-of-band interference without the need for additional hardware associated with anti-aliasing filters.
In summary, our key contributions to this paper include the development of an SDR-based test bed to characterize the performance of a tunable narrowband antenna within a modern communication channel. Furthermore, the hardware/software modularity of the SDR platform is utilized to automate the antenna’s frequency reconfiguration within the GNU-Radio framework.
|Talk Length||15 Minutes|