Superluminal Waveguides Based on Non-Foster Circuits for Broadband Leaky-Wave Antennas

Non-Foster circuits such as negative capacitors can be used to create superluminal waveguides for broadband leaky-wave antennas. The negative capacitors effectively cancel part of the dielectric constant within the waveguide to provide a broadband relative permittivity between 0 and 1. When used as a leaky-wave antenna, the beam angle is independent of frequency over a broad bandwidth because the waveguide provides a frequency-independent phase velocity greater than the vacuum speed of light. Thus, this approach eliminates beam squint, which is a primary drawback of passive leaky-wave antenna designs. Simulation results using ideal negative capacitors are presented, and the effects of causality are analyzed.