Voltage tunable laminated dielectric materials for a coplanor waveguide
View Patent ↗A tunable dielectric structure includes a first layer of dielectric material, a second layer of dielectric material positioned adjacent to the first layer of dielectric material, with the second layer of dielectric material having a dielectric constant that is less than the dielectric constant of the first layer of dielectric material, and electrodes for applying a controllable voltage across the first dielectric material, thereby controlling a dielectric constant of the first dielectric material, wherein at least one of the electrodes is positioned between the first and second layers of dielectric material. The dielectric materials can be formed in various shapes and assembled in various orientations with respect to each other. The tunable dielectric structure is used in various devices including coaxial cables, cavity antennas, microstrip lines, coplanar lines, and waveguides.
1. A coplanar line comprising:
a first rectangular slab of a horizontally stacked multi-layered stack of rectangular slabs of dielectric material, said first rectangular slab comprising a first side, a second side and two edges, said first rectangular slab having a first dielectric constant;
a second rectangular slab of said horizontally stacked multi-layered stack of rectangular slabs of dielectric material;
said second rectangular slab having a second dielectric constant less than 30, the second dielectric constant less than the first dielectric constant;
a first electrode adjacent to said first side of said first rectangular slab of dielectric material and a second electrode adjacent to said second side of said first rectangular slab of dielectric material, said first electrode and said second electrode for applying a controllable voltage across said first rectangular slab of dielectric material thereby controlling the first dielectric constant of said first rectangular slab of dielectric material said second rectangular slab comprising a first side, a second side and two edges;
a center strip positioned with a side of said center strip perpendicular to said first side of each of said first and second rectangular slabs of dielectric material; and
a first ground plane positioned with a side of said first ground plane perpendicular to said first side of each of said first and second rectangular slabs of dielectric material; and
a second ground plane positioned with a side of said second ground plane perpendicular to said first side of each of the first and second rectangular slabs of dielectric material, wherein said center strip is positioned between said first ground plane and said second ground plane.
2. A coplanar line as recited in claim 1 , further comprising:
means for applying a controllable voltage across said second rectangular slab of dielectric material, thereby controlling the dielectric constant of said second rectangular slab of dielectric material.
3. A coplanar line as recited in claim 1 , further comprising:
a plurality of additional rectangular slabs of dielectric material horizontally stacked with said first and second rectangular slabs, said additional rectangular slabs of dielectric material include at least one layer having a tunable dielectric constant.
4. A coplanar line as recited in claim 3 , wherein said first, second and additional layers of dielectric material are assembled into a plurality of subassemblies, said subassemblies having the same arrangement of dielectric materials.
5. A coplanar line as recited in claim 1 , wherein said first rectangular slab of dielectric material has dielectric constant greater than about 100 and a loss tangent of less than about 0.01.
6. A coplanar line as recited in claim 1 , wherein said second rectangular slab of dielectric material is selected from the group consisting of Ba 1-x Sr x TiO 3 composite where x ranges from zero to one, alumina, mica, and air.
7. A coplanar line as recited in claim 1 , wherein said first and second rectangular slabs of dielectric material are selected from the group consisting of bulk, tape, thick film and thin film layers.
8. A coplanar line as recited in claim 1 , wherein said first and second rectangular slabs of dielectric material each have a thickness less than about one tenth of the wavelength of a radio frequency signal to be transmitted through the coplanar line.
9. A coplanar line as recited in claim 1 , wherein said first rectangular slab of dielectric material is selected from the group consisting of BSTO, BSTO-MgO, BSTO-MgAl 2 O 4 , BSTO-CaTiO 3 , BSTO-MgTiO 3 and BSTO-MgSrZrTiO 6 .