30 GHz Electronically Steerable Antennas Using Ba_xSr_1−xTiO₃-Based Room-Temperature Phase Shifters

Abstract

We report the performance of 16-element phased array antennas operating at 30 GHz and ambient temperature. These antennas use BaxSr1−xTiO3(BST)-based phase shifters to produce the beam steering. Ferroelectric phase shifters offer advantages over current semiconductor and ferrite devices including faster switching speeds and lower costs. Also, ferroelectric phase shifters offer higher power handling capability than semiconductor devices and also have high radiation resistance. We made phase shifters from laser-ablated epitaxial BST films as well as from polycrystalline BST-oxide composite films. Although neither the devices nor the materials themselves are fully optimized, phase shifters have shown > 360° of phase shift with < 350 V DC bias (E < 9 V/µm) and ∼8 dB insertion loss. With ferroelectric phase shifters incorporated, antennas show radiation patterns with central-lobe half-power widths of ∼13° and side lobe intensities down by more than 10 dB. Using the phase shifters, the central lobe can be shifted, or “steered,” by ±18° in either direction. These results demonstrate a first step toward a prototype steerable antenna for 20–30 GHz satellite communications as well as other applications.

Computer Simulation of Polarization vs. Electric-Field Curves of Non-Linear Dielectrics and Macromodel for SPICE simulator

“…In the frequency-tunable capacitors, nonlinear dielectrics such as strontium barium titanate are used to change the dielectric permittivity with dc-bias field. 3) The piezoelectric microactuator is a key device in many MEMS applications. The actuator is usually made of PZT-based thick films, where the P-E curve is nonlinear even in unipolar driving.…”

Strain Effects on the Dielectric Properties of Epitaxial SrTiO3Thin Films Grown by Pulsed Laser Deposition

“…The differences between bulk and thin film behavior have been attributed to decreased crystallinity, variation in cation stoichiometry, interface or 'size' effects, and residual strain from lattice mismatch, differential thermal expansion, and the growth process itself [12][13][14][15][16][17][18].…”

Thickness dependence of the properties of epitaxial barium strontium titanate thin films

“…Currently, dielectric properties of Ba x Sr 1 -x TiO 3 (BST) thin films have been actively studied because of their potential use in controlled electronic devices of data transmission in millimeter and submillimeter ranges [1][2][3][4][5][6] and in optical ultrafast analog modula tors [3]. It was experimentally shown that properties of thin ferroelectric films in such devices differ signifi cantly from corresponding properties of bulk materials [1][2][3][4].…”

“…It was experimentally shown that properties of thin ferroelectric films in such devices differ signifi cantly from corresponding properties of bulk materials [1][2][3][4]. In general, films have a lower permittivity and high dielectric losses, which results in device parame ter degradation [1][2][3][4].…”

“…It was experimentally shown that properties of thin ferroelectric films in such devices differ signifi cantly from corresponding properties of bulk materials [1][2][3][4]. In general, films have a lower permittivity and high dielectric losses, which results in device parame ter degradation [1][2][3][4]. The supposed causes of this dif ference between films and bulk materials are the crys talline structure imperfection [3], changes in cation stoichiometry [7], the effect of the interface (or the size effect) [8], residual stresses [3,5,[8][9][10] due to lat tice mismatch, differences in thermal expansion coef ficients, generation of spontaneous strain during the paraelectric to ferroelectric phase transition, and growth mechanisms.…”