What is claimed is:
1. An array antenna which comprises:
an array of radiator elements;
a stripline feed for the radiator elements;
a metal component which includes a first portion having an upwardly facing surface at a first level, and a second portion having a downwardly facing surface at a second level, the radiator elements being above the first portion, the second level being higher than the first level, and the stripline feed being at a third level between the first and second levels.
2. An antenna according to claim 1 wherein the metal component is in the form of a metal sheet which is shaped to form said first portion, said second portion, and an intermediate portion which extends from the first portion to the second portion.
3. An antenna according to claim 2, wherein the metal sheet is of an un-annealed aluminium.
4. An antenna according to claim 3, wherein the metal sheet is formed by pressing, in a deep drawing tool.
5. An antenna according to claim 2, wherein, in respect of each of the radiator elements, there is an opening in the intermediate portion, the stripline feed having an extension which passes through the opening to the respective radiator element.
6. An antenna according to claim 2, wherein said second portion is between a pair of said radiator elements, and wherein there is a said first portion and a said intermediate portion on each opposite side of the second portion, thereby to form a channel in the underside of the metal sheet, the stripline feed being in the channel.
7. An antenna according to claim 6, which further comprises a sheet of conductive foil which extends across the channel on the underside of the metal sheet, said second portion forming an upper ground plane for the stripline feed and said sheet of conductive foil forming a lower ground plane for the stripline feed.
8. An antenna according to claim 7, wherein said sheet of conductive foil has opposite edge portions which overlie and are adhesively secured to the underside of the respective first portions.
9. An antenna according to claim 1, wherein each radiator element is separated from said first portion by a spacer element which is of an extruded plastics material having a cellular configuration in cross-section.
10. An antenna according to claim 1, wherein the stripline feed is held between spacer strips which are of an extruded plastics material having a cellular configuration in cross-section.
11. An array antenna which comprises:
a metal sheet having an upper side and a lower side;
an array of radiator elements on the upper side of the metal sheet, each radiator element being separated from the metal sheet by a spacer element of dielectric material; and
a stripline feed for the radiator elements, the stripline feed being on the lower side of the metal sheet;
the metal sheet being shaped to have a first portion which is at a low level, a second portion which is at a high level, and an intermediate portion which extends from the first portion to the second portion; and
the arrangement of the radiator elements and the stripline feed in relation to the metal sheet being such that said first portion forms a ground plane for the radiator elements, and said second portion forms an upper ground plane for the stripline feed.
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 lighting control device for controlling luminance of a lighting means by performing pulse width modulation control on voltage applied to the lighting means comprising:
a current detecting means for detecting a load current applied to the lighting means;
a duty ratio deciding means for deciding a duty ratio used in the pulse width modulation control such that the duty ratio is (A1Ap)2, based on a theoretical value electric current A1 set based on a predetermined luminance factor provided for the lighting means and a load current Ap detected by the lead current detecting means; and
a modulation controlling means for performing the pulse width modulation control on the voltage applied to the lighting means using the duty ratio decided by the duty ratio deciding means.
2. The lighting control device according to claim 1, comprising:
a luminance factor deciding means for deciding a luminance factor of the lighting means based on an external switch state and a signal from an external sensor.
3. The lighting control device according to claim 1, wherein the luminance factor is consecutively changed by an external unit.
4. The lighting control device according to claim 1, wherein:
a plurality of lighting means is provided;
the current detecting means is provided for each of the plurality of lighting means; and
the duty ratio deciding means decides a duty ratio used in the pulse width modulation control for each of the plurality of lighting means such that a difference in luminance among the plurality of lighting means is minimal, based on luminance factors of the plurality of lighting means and each load current of the plurality of lighting means detected by the current detecting means.
5. The lighting control device according to claim 1, further comprising:
a storing means for storing characteristic constant numbers related to different kinds of lighting means; and
a luminance factor deciding means for acquiring a characteristic constant number of the lighting means from the storing means based on the type of lighting means specified externally and deciding the luminance factor of the lighting means based on the characteristic constant number, an external switch state, and a signal from an external sensor.
6. A lighting control method for controlling a luminance of a lighting means by performing pulse width modulation control on voltage applied to the lighting means comprising the steps of:
detecting a load current applied to the lighting means;
deciding a duty ratio used in the pulse width modulation control such that the duty ratio is (A1Ap)2, based on a theoretical value electric current A1 set based on a predetermined luminance factor provided for the lighting means and a load current Ap detected by the lead current detecting means; and
performing the pulse width modulation control on the voltage applied to the lighting means using the duty ratio decided by the duty ratio deciding means.