Open-Stopband Suppression via Double Asymmetric Discontinuities in 1-D Periodic 2-D Leaky-Wave Structures

• Published in: IEEE antennas and wireless propagation letters Vol. 18; no. 10; pp. 2066 - 2070
• Main Authors: Baccarelli, Paolo, Burghignoli, Paolo, Comite, Davide, Fuscaldo, Walter, Galli, Alessandro
• Format: Journal Article
• Language: English
• Published: New York IEEE 01-10-2019; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Asymmetry; Dielectrics; Discontinuity; Gratings; Impedance matching; Leaky modes; Leaky waves; leaky-wave antennas (LWAs); Lenses; Metal strips; Metals; open stopband (OSB); periodic structures; Solvers; Strips; Unit cell; Waveguide discontinuities
• ISSN: 1536-1225; 1548-5757
• DOI: 10.1109/LAWP.2019.2937473

A technique for the open-stopband (OSB) suppression in one-dimensional (1-D) periodic leaky-wave antennas based on a double asymmetric series/shunt discontinuity inside the unit cell is discussed and applied to a canonical 2-D structure. A longitudinal equivalent network formalism is developed here to analyze the unit-cell matching, which confirms that the OSB suppression cannot be achieved using a double symmetric discontinuity. Conversely, an infinite number of matched configurations can be obtained using two unequal passive discontinuities, whose reciprocal distance can be chosen freely inside a continuous range always including a quarter wavelength. The possibility of suppressing the OSB is then shown for both TM and TE leaky modes supported by a metal strip grating on a grounded slab by using independent full-wave modal solvers and considering typical geometries with either narrow metallic strips or narrow slots inside the unit cell.