1. A filter comprising:
acoustic wave resonators located in a first path connected between an input terminal and an output terminal; and
a cancel circuit including a second path and a first acoustic wave resonator, the second path having a first and a second nodes, each of which is located in the first path so that the second path is parallelly connected to at least a part of the acoustic wave resonators, and one end of the first acoustic wave resonator being connected to a third node that is located between the first and the second nodes in the second path and another end of the first acoustic wave resonator being connected to ground.
2. The filter according to claim 1, wherein
the first acoustic wave resonator has an anti-resonance frequency that is set to a frequency within a transition band between a passband of the filter and a blocking band on a low frequency side of the passband, and a resonance frequency that is set to a frequency within the transition band or a frequency lower than the transition band.
3. The filter according to claim 1, wherein
the cancel circuit includes a capacitor or an acoustic wave resonator that is connected in parallel to the first acoustic wave resonator.
4. The filter according to claim 1, wherein
the first acoustic wave resonator has a resonance frequency that is set to a frequency within a blocking band on a high frequency side of a passband of the filter.
5. The filter according to claim 4, wherein
the first acoustic wave resonator has a resonance frequency that is set to around a frequency that is within the blocking band on the high frequency side of the passband and at which a pass phase of the filter reverses.
6. The filter according to claim 1, wherein
the cancel circuit includes a second acoustic wave resonator that is located in the second path and is connected in series between the first and the second nodes,
the second acoustic wave resonator has an anti-resonance frequency that is set to a frequency within a blocking band on a low frequency side of a passband of the filter or a frequency lower than the blocking band, and
the first acoustic wave resonator has a resonance frequency that is set to a frequency higher than the anti-resonance frequency of the second acoustic wave resonator.
7. The filter according to claim 1, wherein
the cancel circuit includes a capacitor or a second acoustic wave resonator that is located in the second path and that is connected in series between the first and the second nodes.
8. The filter according to claim 1, wherein
the first acoustic wave resonator has two or more resonance frequencies.
9. The filter according to claim 1, wherein
the cancel circuit includes a plurality of the first acoustic wave resonators that have mutually different resonance frequencies.
10. The filter according to claim 1, wherein
the cancel circuit is connected between the input terminal and the output terminal.
11. The filter according to claim 1, wherein
a plurality of the cancel circuits are connected in parallel to at least a part of the acoustic wave resonators.
12. A communication module comprising:
the filter according to claim 1.
13. A duplexer comprising:
a first filter that is connected between an antenna terminal and a first terminal and that includes a first group of acoustic wave resonators that are located in a first path connected between the antenna terminal and the first terminal;
a second filter that is connected between the antenna terminal and a second terminal and that includes a second group of acoustic wave resonators that are located in a second path connected between the antenna terminal and the second terminal, the second filter having a passband higher than a passband of the first filter; and
a cancel circuit including a third path and a first acoustic wave resonator, the third path having a first and a second nodes, each of which is located in the first path or the second path so that the third path is parallelly connected to at least a part of the first or second group of acoustic wave resonators, and one end of the first acoustic wave resonator being connected to a third node that is located between the first and the second nodes in the third path and another end of the first acoustic wave resonator being connected to ground.
14. The duplexer according to claim 13, wherein
the cancel circuit is connected in parallel to at least a part of the second group of acoustic wave resonators, and
the first acoustic wave resonator has an anti-resonance frequency that is set to a frequency within a guard band between a passband of the first filter and a passband of the second filter, and a resonance frequency that is set to a frequency within the guard band or a frequency lower than the guard band.
15. The duplexer according to claim 13, wherein
the cancel circuit is connected in parallel to at least a part of the first group of acoustic wave resonators, and
the first acoustic wave resonator has a resonance frequency that is set to a frequency within a passband of the second filter.
16. The duplexer according to claim 13, wherein
the cancel circuit is connected in parallel to at least a part of the second group of acoustic wave resonators and includes a second acoustic wave resonator that is located in the third path and is connected in series between the first and the second nodes, and
the second acoustic wave resonator has an anti-resonance frequency that is set to a frequency within a passband of the first filter or a frequency lower than a passband of the first filter; and
the first acoustic wave resonator has a resonance frequency that is set to a frequency higher than the anti-resonance frequency of the second acoustic wave resonator.
17. A communication module comprising:
the duplexer according to claim 13.
18. The duplexer according to claim 13, wherein
one of the first and the second nodes is directly connected to the antenna terminal and another of the first and the second nodes is directly connected to the first terminal or the second terminal.
19. The duplexer according to claim 13, wherein
the cancel circuit includes at least one of a capacitor and a second acoustic wave resonator that is located in the third path and that is connected in series between the first and the second nodes.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A method for preparing an electrically switchable reflection hologram, comprising:
disposing a polymer-dispersed liquid crystal material between transparent plates, wherein the polymer-dispersed liquid crystal material comprising, before exposure:
(a) a polymerizable;
(b) a liquid crystal;
(c) a cross-linking monomer;
(d) a coinitiator; and
(e) a photoinitiator dye;
disposing the polymer-dispersed liquid crystal material within a magnetic field wherein the orientation of at least a portion of the magnetic field is directed along an axis substantially parallel to the plane of the plates; and
exposing an interference pattern inside the polymer-dispersed liquid crystal material while the polymer-dispersed liquid crystal material is disposed within the magnetic field.
2. A method for preparing a switchable reflection hologram, comprising the steps of:
disposing a polymer-dispersed liquid crystal material between transparent plates;
exposing an interference pattern inside the polymer-dispersed liquid crystal material; and
applying a shear stress field whereby the symmetry axis of the liquid crystal is oriented substantially parallel to the transparent plates.
3. A switchable reflection hologram comprising:
a polymer-dispersed liquid crystal material wherein the reflective material is disposed adjacent to the polymer-dispersed material and wherein the hologram is made by exposing an interference pattern inside a polymer-dispersed liquid crystal material, the polymer-dispersed liquid crystal material comprising, before exposure:
(a) a polymerizable monomer;
(b) a negative dielectric anisotropy liquid crystal;
(c) a cross-linking monomer;
(d) a coinitiator; and
(e) a photoinitiator dye.
4. The switchable reflection hologram of claim 3, wherein the negative dielectric anisotropy liquid crystal comprises a combination of positive dielectric anisotropy liquid crystals and negative dielectric anisotropy liquid crystals whereby the liquid crystal has a negative dielectric anisotropy at the frequency of the electric field.
5. The switchable reflection hologram of claim 3, wherein the negative dielectric anisotropy liquid crystal comprises:
4
6. The switchable reflection hologram of claim 3, wherein the negative dielectric anisotropy liquid crystal comprises:
5
7. The switchable reflection hologram of claim 3, wherein the negative dielectric anisotropy liquid crystal comprises:
6
8. The switchable reflection hologram of claim 3, wherein the negative dielectric anisotropy liquid crystal comprises:
7
9. The switchable reflection hologram of claim 3, wherein the negative dielectric anisotropy liquid crystal comprises:
8
10. The switchable reflection hologram of claim 4, wherein the liquid crystal comprises:
9
11. The switchable reflection hologram of claim 4, wherein the liquid crystal comprises:
p-pentylphenyl-2-chloro-4-(p-pentylbenzoyloxy) benzoate; and
p-heptylphenyl-2-chloro-4-(p-octylbenzoyloxy) benzoate.
12. A switchable reflection hologram made by exposing an interference pattern inside a polymer-dispersed liquid crystal material in the presence of a magnetic field, the polymer-dispersed liquid crystal material comprising, before exposure:
(a) a polymerizable monomer;
(b) a positive dielectric anisotropy liquid crystal;
(c) a cross-linking monomer;
(d) a coinitiator; and
(e) a photoinitiator dye;
wherein the hologram has opposing surfaces and a plurality of polymer regions having a first refractive index and polymer-dispersed liquid crystal regions having a second refractive index disposed substantially parallel to the opposing surfaces of the hologram;
an electrically conductive material associated with each of the opposing surfaces of the hologram and configured so that an electrical field can be applied across the hologram to modify the refractive index of the polymer-dispersed liquid crystal regions; and
wherein the symmetry axis of the positive dielectric anisotropy liquid crystal is oriented substantially parallel to the opposing surfaces of the hologram.
13. A switchable reflection hologram made by exposing an interference pattern inside a polymer-dispersed liquid crystal material in the presence of a magnetic field, the polymer-dispersed liquid crystal material comprising, before exposure:
(a) a polymerizable monomer;
(b) a positive dielectric anisotropy liquid crystal;
(c) a cross-linking monomer;
(d) a coinitiator; and
(e) a photoinitiator dye;
wherein the hologram has opposing surfaces and a plurality of alternating planes of polymer channels having a first refractive index and polymer-dispersed liquid crystal channels having a second refractive index disposed substantially parallel to the opposing surfaces of the hologram;
an electrically conductive material associated with each of the opposing surfaces of the hologram and configured so that an electrical field can be applied across the hologram to modify the refractive index of the polymer-dispersed liquid crystal channels; and
wherein the symmetry axis of the positive dielectric anisotropy liquid crystal is oriented substantially parallel to the opposing surfaces of the hologram.
14. A switchable reflection hologram made by exposing an interference pattern inside a polymer-dispersed liquid crystal material and applying a shear stress field, the polymer-dispersed liquid crystal material comprising, before exposure:
(a) a polymerizable monomer;
(b) a positive dielectric anisotropy liquid crystal;
(c) a cross-linking monomer;
(d) a coinitiator; and
(e) a photoinitiator dye;
wherein the hologram has opposing surfaces and a plurality of polymer regions having a first refractive index and polymer-dispersed liquid crystal regions having a second refractive index disposed substantially parallel to the opposing surfaces of the hologram;
an electrically conductive material associated with each of the opposing surfaces of the hologram and configured so that an electrical field can be applied across the hologram to modify the refractive index of the polymer-dispersed liquid crystal regions; and
wherein the symmetry axis of the positive dielectric anisotropy liquid crystal is oriented substantially parallel to the opposing surfaces of the hologram.
15. A switchable reflection hologram made by exposing an interference pattern inside a polymer-dispersed liquid crystal material and applying a shear stress field, the polymer-dispersed liquid crystal material comprising, before exposure:
(a) a polymerizable monomer;
(b) a positive dielectric anisotropy liquid crystal;
(c) a cross-linking monomer;
(d) a coinitiator; and
(e) a photoinitiator dye;
wherein the hologram has opposing surfaces and a plurality of alternating planes of polymer channels having a first refractive index and polymer-dispersed liquid crystal channels having a second refractive index disposed substantially parallel to the opposing surfaces of the hologram;
an electrically conductive material associated with each of the opposing surfaces of the hologram and configured so that an electrical field can be applied across the hologram to modify the refractive index of the polymer-dispersed liquid crystal channels; and
wherein the symmetry axis of the positive dielectric anisotropy liquid crystal is oriented substantially parallel to the opposing surfaces of the hologram.
16. The birefringent material of claim 12, wherein the polymerizable monomer comprises dipentarythritol hydroxypentaacrylate.
17. The birefringent material according to claim 12, wherein the polymer-dispersed liquid crystal material further comprises, before exposure, a surfactant.
18. The birefringent material of claim 13, wherein the polymerizable monomer comprises dipentarythritol hydroxypentaacrylate.
19. The birefringent material according to claim 13, wherein the polymer-dispersed liquid crystal material further comprises, before exposure, a surfactant.
20. The birefringent material of claim 14, wherein the polymerizable monomer comprises dipentarythritol hydroxypentaacrylate.
21. The birefringent material according to claim 14, wherein the polymer-dispersed liquid crystal material further comprises, before exposure, a surfactant.
22. The birefringent material of claim 15, wherein the polymerizable monomer comprises dipentarythritol hydroxypentaacrylate.
23. The birefringent material according to claim 15, wherein the polymer-dispersed liquid crystal material further comprises, before exposure, a surfactant.