Research affecting the study of microwaves began almost 350 years ago and continues to advance to this day. Instrumental to developing this research, numerous scientists and engineers are immortalized in the history of electromagnetism, radar and radio, as well as semiconductors and superconductors.

In the early 1900's, spark-gap radio transmitters, such as Morse Code, telegraphs, continuous waves, and radio broadcasting became an accepted everyday occurrence. Microwaves were extensively researched in WWII for the British fine-tuned radar for the use of "night vision" used during the Bombing of Britain. Multiple militaries used radar on cargo ships to detect submarines and determine their location.

Microwave communications entered our daily, middle-class lives in the 1950’s as television signals. Long distance telephone signals were transferred using repeater towers. Communication satellites were introduced with the advent of Echo I and quickly upgraded to geosynchronous satellites that both received and transmitted microwave signals. And, of course, cordless phones and cell phones which most of us cannot live without.

Microwave Power Transmission (MPT) has become a special area of research as fossil fuel sources deplete, and once underdeveloped countries enter the ranks of technologically developing nations. The possibility of using microwaves to deliver power to remote areas of the earth from solar satellites or other space alternatives has become a primary research topic. From Tesla’s coil in Colorado Springs, to Brown’s remotely powered helicopter, to JPL’s demonstration at the Venus Site at Goldstone, and to the Solar Powered Satellite Project sponsored by the Department of Energy and NASA, we can see the foundation for more power opportunities.

Prior to citing our related grants, we would like to present three patents granted by the US Patent Office that directly support our project's goal.

• #3989994  Space oriented microwave power transmission system by William C. Brown (August 9, 1974) outlines an active phased antenna array for solar power satellite systems. The device includes microwave energy generators that convert DC power generated from the solar cells to microwave energy. The microwave energy is transmitted in a narrow beam through space to a receiving point for capture and rectification. The microwave energy generator is a cross-field amplifier type of high efficiency and long life with the use of a cold cathode secondary emitting electron source. The microwave power is transmitted through slotted waveguide radiator arrays, and the phase of the energy is monitored and corrected with phase shifting devices when needed.
• #5321414  Dual polarized dipole array antenna by Adrian W. Alden and Tom T. Ohno (June 14, 1994) outlines a dual polarized dipole array antenna for the purpose of high efficiency power transmission or reception in the form of electromagnetic waves. The device consists of an array of antennas connected with transmission lines symetrically aligned on a dielectric layer. Rectifiers and wave filters on the transmission lines rectify the outputs of each antenna element.
• #6114834  Remote charging system for a vehicle by Ronald J. Parise (November 8, 1999) outlines a system to power an electric or electric/hybrid vehicle. The system includes a power transmission unit mounted to a pole that is connected to the local power grid. The vehicle includes a translocator device that transmits a signal to the power transmission unit, which contains a device that detects the translocator signal and tracks the location of the vehicle. The power transmission unit receives the translocator signal, locks onto the vehicle, transmits a wireless energy beam to an antenna mounted on the vehicle, and follows the path of the vehicle until the translocator signal is lost or interrupted. The antenna transfers the electrical energy to an electrical energy storage device. The translocator signal is transmitted until the energy storage unit reaches a predetermined level of charge.

Now we would like to present three grants that support our product and its development:

1. In 2003, The National Science Foundation Office of International Science and Engineering awarded a one-year grant to the United States-Japan Joint Seminar: Space Solar Power Systems, in the amount of $30,000. This grant was awarded to the Space Solar Power Satellite project for renewable sources of energy obtained by collecting solar power in space, transforming the energy into a high power microwave beam that is directed to the surface of the earth. On the ground, the microwave beam is rectified into DC power for delivery and storage. The United States and Japan have a common interest in developing alternatives to oil and nuclear power, hence the motive for this project.
   
   
2. In 2003, the National Science Foundation Division of Electrical, Communications and Cyber Systems awarded a one-year grant for Microwave Research Instrumenation Acquisition at Bradley University, in the amount of $265,500. This grant will allow "Bradley University" to purchase equipment that will facilitate research on the subject of compact, broadband/high-speed monolithic microwave integrated circuits and antennas (MMICs). The goals of this project are to improve microwave engineering laboratories for continued research and design at high frequencies in the areas of MMICs, hybrid-MICs, and printed antennas, to increase collaboration within industry for the design of MMICs for current and future generation communication systems, to expand training in advanced research, design, tests, and measurements for students, and to improve Bradley University's ability to seek research funding from industry and the government.
   
   
3. The United States Department of Energy Office of Fusion Energy Science granted $2.7 million to Professor Raymond Fonck, director of the Pegasus Plasma Experiment in the Department of Engineering Physics at the University of Wisconsin-Madison. Pegasus is a large toroidal device surrounded by magnetic coils that help stabilize and confine the plasma in the reactor's vacuum. The device is a sphere with a hole through the middle, more spherical than toroidal. It is smaller and cheaper to develop that other fusion reactors. The goal of Pegasus is to explore what happens when the hole becomes as small as possible. The smaller the hole, the more efficient the system because the less magnetic field needed to keep the plasma stable. In this high-pressure-to-low-magnetic field ratio, Fonck encountered stronger-than-expected instabilities. At that point, the experiment was bounded by the 30 year old equipment. This grant will allow the department to upgrade its power, control, and diagnostic systems.
   
   

In 1975 the Jet Propulsion Laboratory (JPL) Goldstone Facility successfully performed an experiment on microwave power transmission located in Goldstone, California. The Goldstone team accomplished this task at the 2.5 GHz band over a 1.6 km distance from an antenna dish to a rectenna. The team was able to produce an 84% efficiency with a 30 kW DC output. Small dipole antennas, in the heart of the rectenna, are connected to the Schottky-barrier diode. The Schottky-barrier diodes collectively act as the converter by transforming the microwaves into DC power.



Stationary High Altitude Relay Platform (SHARP) is a one-eighth scale remote control plane meant to fly in circles to provide surveillance, monitoring services, and way to relay communications. The plane will fly for months at an operating altitude of twenty-one kilometers. It would maintain flight while powered by microwaves sent to it from a large antenna array on the ground. The plane was redesigned with slender wings and a large area on the body for the rectennas to pick up the microwaves.



Dating back to WWII, aircrafts were identified by using Radio Frequency Identification (RFID) to tell if the aircraft was a friend or foe. Today, the use of RFID technology has sky rocketed and is used to identify the most basic items that you can purchase at you local superstore. Basically, "passive" RFID systems are devices that transfer information from a memory source without using a connected energy source. The information transfer happens when the RFID comes into the path of directed electromagnetic waves that produce enough energy to allow the RFID to send it data within a frequency between 860 MHz and 960 MHz. Then the RFID will reflect the information in a way that can be read by the reader.



Developed by Raytheon in 2005, the Active Denial System uses high powered microwaves to cause pain for the person it is pointed at. It uses microwaves at a frequency of 95 GHz, which penetrate the skin and cause the water in the skin to be excited. This causes an intense pain sensation which is not permanently damaging. At the depth of half (0.5) of a millimeter instantly produces a heating sensation, which causes the victim to attempt to run away. The effects of the beam end as soon as the subject is not in a place it's pointing, or when the beam is turned off. The sensation is that of having a hot frying pan pressed against the skin. It is said to have a range of 700 yards.



In 1994, a group of scientists from l'Université de la Réunion began the design of a wireless power transmission case study on the French island of La Réunion, near Madagascar. The team was lead by Dr. Jean-Daniel Lan-Sun-Luk, and presented its preliminary design at the WPT(wireless power transmission) Conference in 1995. From there, they began working on the case study.



The model would be capable of transmitting wireless power to a small, isolated village on La Réunion known as Grand-Bassin. This tiny village has a population under 200, is surrounded by high canyon walls on all sides, and has no road access. Its natural isolation made it a perfect candidate for a wireless power transmission study as it did not receive any electricity at the time, and other proposals of power transportation were either too expensive or less efficient. In the study, 10 kW of power would be transmitted over a distance of 700 m. As this was not a purely vertical transmission, as SHARP was, human safety would be a concern, which lead the team to choose such a low power. The system would have 17.5 kW of power, thus giving it an overall efficiency of 57%. The transmitter unit would use a conventional magnetron and a projecting antenna array, which focused the power using a MultiFoci Parabolic Reflector antenna (MPR) developed specifically for this product. The power would then received with a rectenna array near the village. This benefited the team, as recent calculations show that any system which operates at efficiencies greater than 20% will be advantageous over photovoltaic cells.



The team published their results in 1997. They then built a prototype, and finished this in 2001. The project was presented at the Wireless Power Transmission conference in 2001, which was held on the island. In correspondence with M. Lan-Sun-Luk, he stated that the team has been able to increase the overall efficiency of the system to 70%.1 He also stated that while "no concrete installation is considered for the moment" the cost of the project would be estimated to be "1 million dollars for 10 kW." Below is an image of the WPT 2001 conference, with the prototype rectenna behind them. This image was provided through email from M. Lan-Sun-Luk.