María Roig

Liquid crystal-based tunable CRLH-transmission line for leaky wave antenna applications at Ka-Band

In this work, a liquid crystal based tunable composite right/left-handed transmission line for future leaky wave antennas working at the Ka-band is presented. The tuning of the liquid crystal is achieved by means of magnetic and electric biasing. For this purpose, different prototypes are fabricated for each biasing technique and their dispersive characteristics compared. Electric tunability is achieved by implementing highly resistive bias lines in the unit cell layout. Both techniques yield similar tuning capabilities at the operation frequency of 27GHz whereas the electric one has the advantage of being easily integratable in the layout.

Investigation on the beam-scanning capability of a gradient index fishnet structure

In this work the beam-scanning capability of a gradient index fishnet array, which is designed to operate at 22.5 GHz, is investigated. The results are discussed based on unit cell simulations and far-field measurements. The gradient is realized by changing the permittivity of a dielectric layer in each unit cell element resulting a tuning of the magnetic resonance frequency. Hence, an effective differential refractive index of 3.8 is achieved at 22.5 GHz yielding a theoretical beam-scanning angle of ±6.6°. Farfield measurements of a 5×5 array confirm the beam-scanning capability with a beam-scanning angle of ±3°. The deviation of the measured results is discussed.

Efficient farfield computation from eigenmode simulations for leaky-wave antennas

An eigenmode based approach for an efficient computation of the farfield radiation pattern of leaky-wave antennas is proposed. By arranging the field distribution obtained from an eigenmode simulation of a single unit cell element the farfield pattern of an array can be predicted in order to reduce the computational effort in terms of time and memory. This approach is demonstrated for a composite right/left-handed (CRLH) leaky-wave antenna with forward and backward radiation. The farfield patterns for different propagations and leakage factors are presented.