Communications: radio wave antennas – Antennas – Slot type
Reexamination Certificate
1999-09-17
2001-01-16
Wong, Don (Department: 2821)
Communications: radio wave antennas
Antennas
Slot type
C343S771000
Reexamination Certificate
active
06175337
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to military antennas for applications where high-gain, high-peak and -average microwave power, compactness, and ruggedness are requirements for Directed Energy Weapons (DEWs) and radars.
2. Discussion of Related Art
In-order-to meet the radiated power and tunable waveform requirements for DEWs and radars, high-gain, high-peak and -average microwave power antennas are needed. The antennas must be compact and rugged to give reduced electromagnetic (EM) and visual signatures and to survive under various battlefield conditions such as high-wind, extreme temperatures, vibrations, etc. The antennas need high-gain characteristics above 30 dB
i
to make the prime power system, power conditioning and power managing systems, HPM source, ancillary equipment, and the overall integrated system highly efficient, low-cost, and compatible with mobility and maneuverability requirements for light forces. Practical applications of EM directed energy systems on the tactical battlefield demand the highest achievable antenna gains for the minimum antenna physical cross-section. These attributes are at obvious conflict. The desired size of the antenna is governed by the sizes of the available prime movers and their road and transport-ability. It is desired that any DEW antenna be no larger than the size of a standard tactical shelter. The antenna should have a gain of 30 dB
i
or better with a main lobe beam width of on the order of a few degrees. It should represent a major improvement over present parabolic dish and horn designs.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to fulfill the urgent military need for compact, high-gain/high-power antennas that are rugged for the battlefield environments and are compatible for mobile, tactical platforms with DEWs and radars.
Briefly, the foregoing and other objects are achieved by using a resonant array of four dielectric loaded waveguide modules containing longitudinal slots. The dielectric material inside the waveguide is chosen to have a low-loss tangent, high-voltage breakdown potential, and a dielectric constant to give a waveguide wavelength that is reduced by at least a factor of 2 (preferably 3 or 4) over that of the corresponding free-space wavelength. The four-module structure is selected where the feed structure distributes power equally to the four modules. On the outside surface of the four-module array, in contact with the surface containing the longitudinal slots, is a dielectric material structure. It is tailored to have the same dielectric constant of the waveguide material at the inner most surface, and then incrementally or continuously reduced to have a dielectric constant close to that of the free-space value at the outer surface further distance from the waveguide array.
In another embodiment, on the outside surface of the four-module array, in contact with the waveguide surface containing the longitudinal slots is a Photonic Bandgap (PBG), high-impedance EM structure with a band gap corresponding to the designed bandwidth and frequency of operation for the antenna. The PBG structure has an effective dielectric constant equal to the dielectric constant of the material inside the waveguide. It has a high-impedance EM surface. It has channel defects that are equal in number to the waveguide slots, perfectly aligned with the slots, and it has a geometrically equivalent cross-sectional area equal to that of the four-module array. The channels serve as radiating paths in the PBG structure. The PBG structure eliminates propagating surface waves, gives image currents that are in phase, and confines the radiation to the channels.
In the preferred embodiment, the invention places the PBG, high-impedance EM structure in contact with the waveguide surface containing the longitudinal slots, and places the tailored dielectric material structure in contact with the PBG structure. The tailored dielectric structure at the inner most surface has the same effective dielectric constant of the waveguide material and the PBG structure. The effective dielectric constant is then incrementally or continuously reduced to have a dielectric constant close to that of the free-space value at the outer surface further distance from the waveguide array. The tailoring of the effective dielectric constant is achieved by layering a given number of slabs of different dielectric constants with sequentially reduced values. Also, one can achieve tailoring of the effective dielectric constant by varying the chemical composition of the material, or by varying the density of a very high dielectric material imbedded in a very low dielectric material.
REFERENCES:
patent: 5717410 (1998-02-01), Ohmine et al.
patent: 5757329 (1998-05-01), Hoover et al.
patent: 5844523 (1998-12-01), Brennan et al.
patent: 6037908 (2000-03-01), Phillips et al.
Jasper, Jr. Louis J.
Merkel George
Miletta Joseph R.
Clohan, Jr. Paul S.
The United States of America as represented by the Secretary of
Tran Chuc D
Wong Don
LandOfFree
High-gain, dielectric loaded, slotted waveguide antenna does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with High-gain, dielectric loaded, slotted waveguide antenna, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and High-gain, dielectric loaded, slotted waveguide antenna will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2517836