Modelling of a BST-0.5 Idc With Application in Electronically Scanned CRLH Lwa

Abstract

Abstract-Modeling of a ferroelectric interdigital capacitor (IDC) and its incorporating in composite right/left-handed (CRLH) unit cells is represented. To evaluate the capacitance of a multi-layered IDC structures, conformal mapping and partial capacitance methods are utilized. Furthermore, the partial displacement method is utilized to calculate the electric field distribution and the its relation in the ferroelectric layer to applied voltage is obtained. Using this relation in a phenomenological model, dependency of the relative permittivity of ferroelectric on the applied voltage is obtained. The designed unit cell is comprised of IDCs and spiral inductors. To alter the propagation constant of the unit cell by varying the applied voltage, a thin layer of Ba 0.5 Sr 0.5 T iO 3 (BST-0.5) ferroelectric is incorporated underneath an IDC, called BST-0.5 varactor. The periodic structure based on the designed unit cell leads to a CRLH LWA. The Tunability of the periodic structure with three unit cell is demonstrated by varying the relative permittivity of the ferroelectric layer.

Composite Right/Left-Handed Leaky-Wave Antenna with Electrical Beam Scanning Using Thin-Film Ferroelectric Capacitors

“…Conversly, MDM FE structures demonstrate higher tunability with lower control voltage values [18,19]. For example, in [20], thin-film barium strontium titanate (BSTO) varactors were used in a CRLH phase shifter with control voltages up to 15 V. The design of a CRLH LWA unit cell with integrated thin-film ferroelectric varactors was presented in [21]. The proposed structure of the CRLH LWA unit cell was analyzed, and simulation results of its dispersion were presented.…”

Modelling the inhomogenity of the ferroelectric layer in a multilayered IDC

“…The electric field components in the ferroelectric layer for the periodical section of an IDC ( Fig. 1 (a)) is [5]:…”

“…(1) and Maxwell 12 simulator. Therefore, initially the electric field, in the ferroelectric layer, is obtained for a large value of ε 2 and then it is substituted in a phenomenological model [5] in order to calculate the exact value of the ferroelectric layer permittivity. Fig.…”

“…In order to modelling the inhomogenity of the ferroelectric layer with thickness of h 2 , in a multilayered IDC, [5] proposed to calculate the electric field at the middle of two strips and 0.25 h f away from them and relating this value of the electric field to the electric field of the whole ferroelectric layer based on the concept that the most effective region, to calculate the capacitance of an IDC, is the region between two strips and near of them. However, in this paper more developed methods have been represented and validated.…”

Broadband and wide range tunable phase shifter based on composite right/left handed transmission line

“…The capacitance of varactor diode varies continuously when the DC voltage is changed. The quality factor Q is acceptable to reduce loss, hence it is suitable for designing tunable analog phase shifters with good performance, such as compact size, low cost, and broad bandwidth.More recently, metamaterial-based phase shifters have also received considerable attention in both scientific and engineering communities [12][13][14][15][16][17][18][19][20][21][22]. In [12], the tunable phase shift reaches 342°by cascading 13 left-handed metamaterials (LHMs) units with operation frequencies from 8 to 10 GHz.…”