Patent Application
20210328638
The present invention relates in general to antenna technology and in particular to a new and useful antenna suitable for use where power and weight are significant considerations in the design of an antenna where range is important.
This invention exploits the performance superiority of directional vs omni-directional antennas.
An antenna gives the wireless system two fundamental properties: gain and direction. Gain is a measure of increase in power. Gain is the amount of increase in energy that an antenna adds to a radio frequency (RF) signal. Direction is the shape of the transmission pattern. As the gain of a directional antenna increases, the angle of radiation usually decreases. This provides a greater coverage distance, but with a reduced coverage angle. The coverage area or radiation pattern is measured in degrees. These angles are measured in degrees and are called beamwidths.
An antenna is a passive device which does not offer any added power to the signal. Instead, an antenna simply redirects the energy it receives from the transmitter. The redirection of this energy has the effect of providing more energy in one direction, and less energy in all other directions.
An ideal omni-directional antenna has a theoretical uniform three-dimensional radiation pattern (similar to a light bulb with no reflector). In other words, an isotropic omni-directional antenna has a perfect 360 degree vertical and horizontal beamwidth or a spherical radiation pattern. It is an ideal antenna which radiates in all directions and has a gain of 1 (0 dB), i.e. zero gain and zero loss.
It is an object of the invention to provide an antenna system which provides greater range than conventional omnidirectional antennas while using substantially the same amount of, or less, power.
It is another object of the invention to provide an antenna system suitable for use on drones or other lightweight vehicles where weight and power are significant considerations, but where range is also a significant objective.
A principal feature of the invention is a system of antenna components, arranged so as to permit in the aggregate transmission over an effective 360 degrees as an omnidirectional antenna, while permitting selection of one of the components so as to reduce the amount of energy required.
These and other objects, features and advantages which will be apparent from the discussion which follows are achieved, in accordance with the invention, by providing an antenna system having a series of antennas, disposed evenly around a 360 degree platform and under control of a system which permits determining which of said antennas is pointed toward a receiver and selectively powering that determined antenna.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its advantages and objects, reference is made to the accompanying drawings and descriptive matter in which a theoretical embodiment and a working prototype of the invention is illustrated.
The foregoing and still other objects of this invention will become apparent, along with various advantages and features of novelty residing in the present embodiments, from study of the following drawings, in which:
Omni-directional and Directional radiation patterns are shown in
While an omni-directional antenna radiates the RF energy uniformly in all directions as per the left image above, directional antennas focus the RF energy in a particular direction. As the gain of a directional antenna increases, the coverage distance increases, but the effective coverage angle decreases. For directional antennas, the lobes are pushed in a certain direction and little energy is there on the back side of the antenna as per the right image above.
Concluding, the fundamental omnidirectional antenna advantage Vs the directional is that it covers all 360 degrees around it without dead zones. Its main disadvantage is that its gain is significantly reduced compared to a directional one and therefore the data link range achieved when omnis are employed is considerably reduced compared to directional antennas.
Drone manufacturers use only omni-directional antennas on the airborne datalink side to make sure they will cover all possible directions around the drone. Directional antennas cannot be used on such platforms since the drone has an unpredicted flight path and continuously changes headings. Therefore, if a directional antenna was to be employed, there would be no means to keep its beam locked to the direction of the drone Ground Control Station resulting in a frequently broken data link. For this reason, directional antennas cannot be used onboard drones. Since omni-directional antennas are currently the only antennas used on drones, the airborne data link has a reduced coverage range and degraded quality.
The aforementioned invention allows the use of four (4) directional antennas, each one with 90 degrees beam width. Combining the 4 beams into a single structure (array) we get a coverage similar to the omnidirectional antenna but with significantly improved gain and consequently improved range (more than double). The prototype was manufactured using four directional antennas, which proved suitable for the purposes of proving the workability of the concept. Other embodiments could, of course, be built with other configurations, for example with eight antennas each one with 45 degrees of bandwidth. Preferably, other embodiments would distribute the individual antennas equally (i.e., the same separation of each individual antenna from its nearest neighbor), and most preferably the number of antennas would be a multiple of four.
The heart of the invention is a circuit called Geospatial antenna controller (GAC). The GAC employs as main components a microprocessor unit (MCU) and microwave RF switches. The MCU receives geospatial data (attitude, position and positional relations) from an integrated inertial measurement unit (IMU), runs fast algorithms to decide which antenna to activate each time and commands the RF switches accordingly.
The outcome of this technology is that the smart antenna more than doubles the range of the drone data link. If for example, a drone can be controlled from the Ground Control Station over a range of 5
Km with an omni antenna, this range becomes 10 Km with the use of the Geospatial Smart Antenna (GCSAnt).
The relative beamwidths and associated gain between the array of 4 directional antennas and the single omni antenna are presented in
This technology can be used on mobile platforms of any kind (Airborne, Land Based, Sea based) to increase their data links range and improve the quality of the data transferred. Specifically, this technique has never been used before on unmanned systems.
The multielement antenna is shown conceptually on
A working prototype is shown in
However, the autopilot is an off-the-self product that has its own firmware. This firmware is open source. As I explained above, we modified this open source firmware to work with our controller.
Also, the antenna radiating elements are off-the-self components that we buy from 3rd party antenna manufacturers.
This application is entitled to, and claims the benefit of, priority from U.S. Provisional Application Ser. No. 62/240,083, filed Oct. 12, 2015, which is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 62240083 | Oct 2015 | US |
