Inventors: Evangelos Foutzitzis and Javier Santoro

This application is entitled to, and claims the benefit of, priority from U.S. Provisional Application Serial No.62/240,083, filed October 12, 2015 _» which is incorporated herein by reference.

FIELD AND BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates in general to antenna technology and in particular to a new and useful antenna oiritiblu for use where power and weight are significant considerations in the design of an antenna where range is important.

Background Information

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 arc measured in degrees and arc 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.

Qmni-dircctional Vs directional antennas

An ideal omnidirectional antenna has a theoretical uniform three-dimensional radiation pattern (similar to a light bulb with no reflector). In other words, an isotropic omnidirectional 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.

SUMMARY OF THE INVENTION

It is an object of me 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 arc 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 arc 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.

BRIEF DESCRIPTION OF THE DRAWINGS

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:

Figure 1 is an illustration of the radiation patterns of omnidirectional and directional antennas. Figure 2 is an illustration of gain and beamwidth of various antenna configurations. Figure 3 is a schematic overview of a multi -antenna system.

Figure 4 illustrates a working prototype of the invention and a prior art omnidirectional antenna. Figure 5 is a schematic of the circuit board used in controlling the prototype of Figure 4.

Figure 6 shows the specifications of the core antenna printed circuit board.

Figure 7 shows the printed circuit board of Figure 6 with tour untennas attached.

Figure 8 is code suitable for controlling the antenna system of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Omni-directional and Directional radiation patterns are shown in Figure 1.

While an omni-directional antenna radiates the RF energy uniformly in all dirfrtiono 03 pta the left image abuvc, 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 u direetionul 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 arc 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 (he 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 Oeospatial 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 S

Km with an omni antenna, this range becomes 10 Km with the use of the Geospatial Smart Antenna (GCSAnt).

The relative bcamwidths and associated gain between the array of 4 directional antennas and the single omni antenna are presented in Figure 2. As shown in Figure 2, the Geospatially

Controlled Smart Antenna, achieves 3-4 times the gain of an Omni-directional antenna while retaining the 360 degrees coverage of the omni-bcam.

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 Figure 3, comprising:

1. The antenna controller board

2. The Antenna Radiating elements

3. The externa] Inertial Measurement Unit (IMU). This can also be a complete autopilot board that includes an IMU. A working prototype is shown in Figure 4, along with a prior art omni antenna. The prototype included:

a. The controller board is presented in schematic form in Figure S. The prototype Core Antenna printed circuit board is shown in Figure 6. The prototype Core Antenna with external antennas attached, as used for themax-rangc flight, is shown in Figure 7. b. The firmware that runs on the controller board microprocessor unit c. We have modified the firmware that runs on the autopilot board so it can control our antenna controller. So the code we have developed runs on the autopilot side and on the antenna controller side. Suitable code is shown in Figure 8.

However, the autopilot is an off-thc-sclf 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 3 ^rd party antenna manufacturers.