A Tunable K-Band Reflector

Active and Passive Lenses from Coupled Square Ring Slots

“…The reflectivity of a simple strip array can be tuned by connecting adjacent strips with capacity controllable varactor diodes and biasing them collectively [26]. Since this concept utilizes only a single periodic metal layer, it can be combined with the here investigated SRS structures on a two-layer PCB.…”

“…7. As in [26], the series RLC connection on the left side of the simplified EQC corresponds to the varactor diode with tunable capacitance C v , component inductance L, and resistance R including mounting parasitics. The periodic strip array beneath the varactors behaves capacitively under TM polarized radiation and is therefore represented by C s .…”

“…Thereby SRS designs are selected, which exhibit center frequencies within the tuning range of the active grid. In [26], the active metasurfaces were realized with varactor diodes MAVR-000120-1141, bridging a slit gap of w s = 0.2 mm. This resulted in EQC parameters R = 3.75 Ω, L = 0.38 nH, and C v between 0.149 pF and 1.0 pF.…”

“…The optimized, passive SRS metasurfaces as well as the above described combinations with a tunable grid were examined as in [6,26] on a quasi optical bench [30]. The corresponding measurement setup is depicted in Fig.…”

“…Since active or passive lumped elements exhibit intrinsic resonances themselves, their application to simple metasurfaces result in promising behaviour especially at high frequencies [26]. As for surfaces without discrete circuit elements, the combination with resonating structures as e.g.…”