Light and RF transparent enclosure for use with asset tracking device
An electromagnetic (RF) and light transparent enclosure having a perforated metallic wall. The enclosure is particularly adapted for an RF wireless tracking system, as a housing for the transmitter device or for a cargo container in or on which the transmitter device is positioned. The enclosure is optically transparent to ensure any photovoltaic device of the transmitter device receives sufficient photons or other energy to power the transmitter device. The RF transparent enclosure attenuates less transmitted and/or received signal at specific frequency bands.
1. A wireless RF transmitter device, the transmitter device comprising:
an RE communication module having an RF operating frequency, the operating frequency having an operating wavelength; and
an enclosure enclosing the communication module, the enclosure having at least one wall comprising a metallic plate having a pattern of apertures therethrough and a dielectric plate adjacent to the metallic plate, each of the apertures having a length and a width, with the apertures arranged in columns and rows, with adjacent apertures in a row having a spacing therebetween, and a spacing between centers of adjacent apertures in adjacent rows, wherein the apertures are shaped, sized and spaced to allow passage therethrough of the RF operating wavelength.
2. The wireless RF transmitter device of claim 1 wherein the apertures comprise circular apertures.
3. The wireless RF transmitter device of claim 2 wherein the circular apertures have a diameter that is no more than ½ of the operating wavelength and that is no less than ¼ of the operating wavelength.
4. The wireless RF transmitter device of claim 2 wherein the spacing between centers of adjacent apertures in a row and the spacing between centers of adjacent apertures in adjacent rows is less than ½ of the operating wavelength.
5. The wireless RF transmitter device of claim 2 wherein the centers of adjacent apertures in a row and the centers of adjacent apertures in adjacent rows form an equilateral triangle.
6. The wireless RF transmitter device of claim 1 wherein the apertures comprise rectangular apertures.
7. The wireless RF transmitter device of claim 6 wherein the apertures comprise crossed rectangular apertures.
8. The wireless RF transmitter device of claim 6 wherein the spacing between centers of adjacent apertures in a row and the spacing between centers of adjacent apertures in adjacent rows are independently no more than one full operating wavelength and is no less than ½ of the operating wavelength.
9. The wireless RF transmitter device of claim 8 wherein the spacing between centers of adjacent apertures in a row is the same as the spacing between centers of adjacent apertures in adjacent rows.
10. The wireless RF transmitter device of claim 6 wherein the centers of adjacent apertures in a row and the centers of adjacent apertures in adjacent rows form and angle that is between 5° and 45°.
11. The wireless RF transmitter device of claim 1 wherein the RF communication module comprises a ZigBee module.
12. The wireless RE transmitter device of claim 1 wherein the RF communication module comprises a ZigBee/LBT module.
13. The wireless RF transmitter device of claim 1 further comprising a positioning element.
14. The wireless RF transmitter device of claim 1 further comprising a sensor array comprising a motion sensor and a machine vision sensor.
15. A wireless RE transmitter device, the transmitter device comprising:
an RF communication module having an RF operating frequency, the operating frequency having an operating wavelength;
a positioning element;
a sensor array; and
an enclosure enclosing at least the communication module, the enclosure having at least one wall comprising a metallic plate having a pattern of apertures therethrough and a dielectric plate adjacent to the metallic plate, each of the apertures having a length and a width, with the apertures arranged in columns and rows, with adjacent apertures in a row having a spacing therebetween, and a spacing between centers of adjacent apertures in adjacent rows, wherein the apertures are shaped, sized and spaced to allow passage therethrough of the RF operating wavelength.
16. The wireless RF transmitter device of claim 15 wherein the RF communication module comprises a ZigBee module.
17. The wireless RF transmitter device of claim 15 wherein the RF communication module comprises a ZigBee/LBT module.
18. The wireless RF transmitter device of claim 15 wherein the sensor array comprises a motion sensor and a machine vision sensor.