Patent Application
20090232602
Embodiments of the present invention relates generally to microwave antennas, sources and leakage protection mechanisms, and more specifically to a directed-energy microwave system for irradiating crop soils to control infestation.
The world's food supply is being greatly diminished because of infestation of fruit and vegetable plants by insects that attack the root system within the soil. The problem is partially controlled by the fumigation of chemical pesticides into the soil after harvest and before planting. However, a potentially more serious problem is created by the accumulation of chemical pesticides in the soil. The pesticides will eventually filter down to the water table, and run-off will occur during rains or irrigation. This diminishes the purity of the water we use for drinking, cooking and bathing. Also, workers applying the pesticides are subjected to a degree of risk to their short-term and long-term health.
Therefore, there is a continuing and unaddressed need in the art for sterilization for crop soil without the use of harmful pesticides.
Embodiments of the present invention relates to a microwave source system for controlling the sterilization of infestation of crop soil.
Embodiments of the present invention replace the chemical pesticide system with a directed energy system that leaves no residual pollutants in the soil after the energy source is switched off.
Embodiments of the present invention use a portable microwave generator that is connected to an applicator that transfers microwave energy from the portable generator into the soil along the rows that will be used for planting. Both the generator and applicator may be mounted on a vehicle that moves over the tops of the rows. An amount of microwave energy is transferred into the soil to be absorbed within the insects or other objects in the soil or by the soil itself. The system may include leakage suppressors that keep the microwave energy directed into the soil and not into the surrounding environment.
Embodiments of the present invention are directed to a system. The system include an applicator connected to a generator to transfer outputted electromagnetic energy from the generator into a section of land. The applicator includes a housing having a shape to substantially conform to the shape created by a soil crop row and ground surrounding the soil crop row. The applicator may also include a portion for receiving the electromagnetic energy outputted from the generator to the applicator. The applicator is configured to transfer at least a portion of the outputted electromagnetic energy into the section of the land.
Other embodiments are directed to a method of directing microwave energy into soil. The method may include activating a microwave generator that is mounted on a vehicle and connected to an applicator that conforms to the topography of a soil crop row. The may further include operating said vehicle so as to transfer at least a portion of the outputted microwave energy from said microwave generator into the soil. The applicator may include at least one leakage suppressor.
Other systems, methods, features, and advantages of the present invention will be or become apparent to one with skill in the art upon examination of the following drawings and detailed description. It is intended that all such additional systems, methods, features, and advantages be included within this description, be within the scope of the present invention, and be protected by the accompanying claims.
Many aspects of the invention can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the present invention. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views.
Embodiments of the present invention relates to a microwave apparatus designed to control the infestation of harmful insects, worms, bacteria and anything else harmful to crops or plants. Other advantages are also realized.
As used herein, “soil” may include the soil and, optionally, living organisms in the ground that are harmful to plants (e.g insects).
As used herein, “insects” may refer to any living organism capable of being located in or on soil. The definition, as used herein, is not limited to the typical meaning of an insect, but to other creatures, such as worms, bacteria, and other creatures of harm to plants or that feed off of plants and/or other objects in or on soil.
As used herein, “vehicle” refers to any apparatus that has a portion that may be operated or placed in motion.
The dimensions and arrangement of individual parts of the applicator may be constructed to distribute the microwave energy over the width of the row (and/or other areas) while preventing energy leakage into the outside environment via at least one microwave leakage suppressor. A portable microwave generator has at least one waveguide or transmission line connected between the generator and the applicator to direct outputted electromagnetic energy (e.g., microwave energy) through the applicator and into the soil. It will be appreciated by those skilled in the art that a wide variety of microwave generators, waveguides and/or transmission lines may be used in conjunction with the present invention.
The generator has an output port to output microwave energy to an input port of the applicator via the waveguide or other device. However, it should be understood that other configurations may be possible, such as connecting the input port of the applicator directly to the output port of the portable microwave generator.
The shape of the waveguide may be configured to guide the microwave transmission into infested soil. The shape of the waveguide, with respect to the microwave power and frequency, may be such that the raypaths of the microwave energy would enter the ground at an angle substantially perpendicular to the soil. This minimizes reflections from the ground causing a maximization of electromagnetic energy into the soil and thus into the pests and insects located within the soil.
An embodiment of the invention includes at least one metal slat or “sled runner.” The metal slats may be made of a microwave reflective material, such as any conductive material. The metal slats may stay in contact with the soil on each side of the crop row to prevent the loss of energy into the environment, thus maintaining the efficiency and safety of the invention. These metal slats may cover different applicators and leakage suppression structures, sled runners and wheels, parabolic reflectors, corner reflectors, horns with no cowl and the like.
The applicator may include a roller system which includes rollers at the end of the metal slats, as illustrated in
In addition to metal slats or sled runners, leakage suppressors or “choke flanges” may be placed at the end of the applicator or metal slats in order to suppress microwave leakage and/or radiation. The leakage suppressors or choke flanges are generally a quarter-wavelength in length.
In one embodiment, each leakage suppressor may have an “L”-shaped unitary member. The leakage suppressor may include a first portion and a second portion, where the second portion extends from a distal end of the first portion in a direction away from an internal space defined by the applicator and ground located directly underneath the applicator. In one embodiment, a plurality of metal slats may be employed. The first portion of the metal slats include a planar sheet of metal extending perpendicular to the ground and extending lengthwise along one side of the applicator. The second portion has a planar sheet of metal connected perpendicularly to the first portion and extends substantially parallel to a section of ground in a direction away from the input port. The second portion may be the only portion of said applicator that makes direct microwave contact with the ground. The length of the second portion is substantially a quarter-wavelength long.
The power of microwave signals propagating through soil is attenuated with respect to distance (z) into the soil as,
is the so-called depth of penetration, ∈s is the relative dielectric constant of the soil (usually ranging from 4 to 7), σs is the conductivity of the soil (usually less than 0.025 S/m) and P0 is the power in watts per square meter entering the soil surface at z=0. Equation (2) is valid for determining δ if σs≦0.0056 fG ∈s, where fG is the microwave frequency in GHz. Thus, for ∈s=5 and fG=0.915, (2) is valid for all σs≦0.025 S/m, the usual range for soil conductivity, and for these parameter values δ≧0.475 m=1.56 ft. Designating the soil as damp (σs=0.025 S/m), normal (σs=0.015 S/m) and dry (σs=0.005 S/m), the corresponding depths of penetration are, respectively: 1.56 ft, 2.60 ft and 7.80 ft.
When heating insects at a particular depth within the soil, the microwave energy must pass through the soil to reach the insects at that depth. The equation used to make this calculation assumes that the target insect is small compared with wavelength. For example, at 0.915 GHz (915 MHz) the wavelength in soil is approximately 0.15 m=150 mm, and the target insects are typically less than few millimeters in diameter. Thus, the power absorbed in watts per cubic meter by an insect at any depth z includes equation (1) and is expressed as [1]:
For example, if P0=100 kW/m2, fG=0.915, σi=3 S/m and ∈i=49, then:
P
a(z)=1.599×106e2z/δW/m3=1.599e−2z/δW/cm3 (4)
It may be assumed that the moisture within the insect is heated by the absorption of microwave energy. Using the fact that 1 calorie of energy will increase the temperature of 1 gram of water by 1° C., the initial rate of temperature increase in the insect is determined by:
P
a
=KpcdT/dt=4.186 joules/cal×1 gm/cc×1 cal/(gm° C.)l ° C./sec)=W/cm3 (5)
Thus,
dT/dt=(1.599/4.186)e−2z/δ° C./sec=0.382e−2z/δ° C./sec (6)
For dry soil conditions, the initial rate of temperature increase within an insect at various depths within the soil is determined from (6) as: z=0, dT/dt=0.382° C./sec=60.38° C./min; z=0.25δ=1.95 ft, dT/dt=0.232° C./sec=13.92° C./min; z=0.5δ=3.90 ft, dT/dt=0.141° C./sec=8.46° C./min and z=δ=7.8 ft, dT/dt=0.052° C./sec=3.12° C./min.
The above applications of the instant invention have been used at 915 MHz. This invention is not limited to this frequency. This invention, including dimensions, microwave source and other relevant parameters, may be modified to a frequency lower than 915 Mhz in order to obtain a greater depth of penetration into the soil. Conversely, the operational microwave frequency may be increased, e.g. 2.45 GHz, in order to increase the concentration of microwave energy into the uppermost layer of the soil.
It should be emphasized that the above-described embodiments of the present invention are merely possible examples of implementations, merely set forth for a clear understanding of the principles of the invention. Many variations and modifications may be made to the above-described embodiment(s) of the invention without departing substantially from the spirit and principles of the invention. All such modifications and variations are intended to be included herein within the scope of this disclosure and the present invention and protected by the following claims.
This application is a continuation of, and claims priority from co-pending, commonly owned non-provisional application Ser. No. 11/329,629, filed Jan. 11, 2006, which claims the benefit of provisional application Ser. No. 60/643,015, filed Jan. 11, 2005, the contents of both of which are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 60643015 | Jan 2005 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 11329629 | Jan 2006 | US |
| Child | 12471173 | US |
