A method and an antenna system are provided for a high-altitude platform (HAP) configured to move in a pattern in the stratosphere to provide coverage to a region of interest and compensate for HAP movement relative to the region of interest. HAP movement is monitored. When it is determined that the HAP has moved relative to the region of interest and, based on the relative movement, a first one of a plurality of antennas in the HAP is no longer able to cover a selected portion of the region of interest, an antenna array switching circuit in the HAP is used to adjust beams transmitted by the antennas by switching to a second one of the plurality of antennas to cover the selected portion of the region of interest, such that the communication services provided to the region of interest are not interrupted due to the movement of the HAP.

In a general aspect, a receiver is disclosed for sensing radio frequency (RF) electromagnetic radiation. The receiver includes a dielectric body having an array of cavities ordered periodically to define a photonic crystal structure in the dielectric body. The dielectric body also has a region in the array of cavities that defines a defect in the photonic crystal structure. An elongated slot through the region extends from a slot opening in a surface of the dielectric body at least partially through the dielectric body. The receiver also includes a vapor or a source of the vapor in the elongated slot as well as an optical window covering the elongated slot. The optical window has a window surface bonded to the surface of the dielectric body to form a seal about the slot opening.

In a general aspect, a radar system includes a photonic crystal receiver. In some aspects, the radar system includes a transmitter station configured to emit probe signals of RF electromagnetic radiation into a region. The radar system also includes a receiver station configured to process return signals of RF electromagnetic radiation from the region. The return signals are based on probe signals scattered from one or more objects in the region. The receiver station includes a photonic crystal receiver formed of dielectric material. The photonic crystal receiver includes an antenna structure, a photonic crystal structure, and a vapor. The receiver station also includes an optical system and a data processing subsystem. The optical system is configured to generate spectroscopic data based on optical signals from the photonic crystal receiver. The data processing subsystem is configured to generate a time series of property data based on the spectroscopic data.

A radar antenna suitable for a drone is provided, which is able to compensate for the agility of drone motion. The radar antenna contains a sandwich of two printed circuit boards between three conductive plates. A first printed circuit board comprises a preferably circular array of first antenna elements such as dipoles. A second printed circuit board, parallel to the first printed circuit board, comprises an array of second antenna elements. One of the array of first antenna elements and the array of second antenna elements is an array of transmission antenna elements and the other an array of reception antenna elements. The first printed circuit board is located below the second printed circuit board. Three conductive plates are used to shape the antenna patterns from the antenna elements so that the main lobes of the antenna patterns are directed obliquely downwards and the antenna patterns from the different array at least partly overlap, suppressing vertical side lobes. A first conductive plate separates the first and second printed circuit boards. A second conductive plate is located above the second printed circuit board, extending radially outward beyond the first conductive plate. A third conductive plate is located below the first printed circuit board. The first conductive plate extends radially outward beyond the third conductive plate.

This invention describes the technology of toroidal CATR (compact antenna test range) for generating multiple directional plane waves propagate toward the center axis of QZ (quiet zone). The toroidal CATR consists of torus as main reflector, sub-reflectors, and the corresponding feed antennas of sub-reflectors. This invention is to provide multiple directional plane waves propagating toward the center axis of torus which is also the center axis of QZ. The performances of QZ in this invention are with larger size of QZ and better electrical performance inside QZ. Due to the capability of multiple directional plane waves propagating toward the center axis of QZ, the complexity of positioner (turntable) for AUT (antenna under test) or radar target RCS (radar cross section) in three dimensional power pattern measurement will be simplified.

In a general aspect, a receiver is disclosed for sensing radio frequency (RF) electromagnetic radiation. The receiver includes a dielectric body having an array of cavities ordered periodically to define a photonic crystal structure in the dielectric body. The dielectric body also has a region in the array of cavities that defines a defect in the photonic crystal structure. An elongated slot through the region extends from a slot opening in a surface of the dielectric body at least partially through the dielectric body. The receiver also includes a vapor or a source of the vapor in the elongated slot as well as an optical window covering the elongated slot. The optical window has a window surface bonded to the surface of the dielectric body to form a seal about the slot opening.

In a general aspect, a system is disclosed for sensing radio frequency (RF) electromagnetic radiation. The system includes a receiver formed of dielectric material. The receiver includes a photonic crystal structure having an elongated slot disposed therein. The receiver also includes an antenna structure extending from the photonic crystal structure and configured to couple to a target RF electromagnetic radiation having a frequency in a range from 100 MHz-1 THz. A vapor or source of the vapor in the elongated slot. The system also includes a laser system configured to provide input optical signals to the elongated slot that interact with one or more electronic transitions of the vapor. The system additionally includes an optical detection system configured to detect the target RF electromagnetic radiation based on output optical signals from the elongated slot.

In a general aspect, a radar system includes a photonic crystal receiver. In some aspects, the radar system includes a transmitter station configured to emit probe signals of RF electromagnetic radiation into a region. The radar system also includes a receiver station configured to process return signals of RF electromagnetic radiation from the region. The return signals are based on probe signals scattered from one or more objects in the region. The receiver station includes a photonic crystal receiver formed of dielectric material. The photonic crystal receiver includes an antenna structure, a photonic crystal structure, and a vapor. The receiver station also includes an optical system and a data processing subsystem. The optical system is configured to generate spectroscopic data based on optical signals from the photonic crystal receiver. The data processing subsystem is configured to generate a time series of property data based on the spectroscopic data.

This invention describes the technology of toroidal CATR (compact antenna test range) for generating multiple directional plane waves propagate toward the center axis of QZ (quiet zone). The toroidal CATR consists of torus as main reflector, sub-reflectors, and the corresponding feed antennas of sub-reflectors. This invention is to provide multiple directional plane waves propagating toward the center axis of torus which is also the center axis of QZ. The performances of QZ in this invention are with larger size of QZ and better electrical performance inside QZ. Due to the capability of multiple directional plane waves propagating toward the center axis of QZ, the complexity of positioner (turntable) for AUT (antenna under test) or radar target RCS (radar cross section) in three dimensional power pattern measurement will be simplified.

A data transmission system for use with a drill string in a primary wellbore is disclosed. The data transmission system includes a toroidal antenna assembly. The toroidal antenna assembly is disposed around the drill string at a primary downhole location within the primary wellbore and configured to transmit a signal from a transmitter. The signal corresponds to sensor data. The toroidal antenna assembly includes a plurality of toroidal antennas, wherein each toroidal antenna is configured to transmit the same signal from the transmitter. Because a plurality of toroidal antennas are utilized to transmit the same signal, construction of the drill string can be more mechanically robust than a conventional insulated gap collar while permitting reliable and fast transmission of sensor data to the surface.