Communications: radio wave antennas – Antennas – Wave guide type
Reexamination Certificate
2000-02-15
2001-08-07
Le, Hoanganh (Department: 2821)
Communications: radio wave antennas
Antennas
Wave guide type
C343S786000
Reexamination Certificate
active
06271799
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to the field of Radio Frequency (RF) communications, and, more particularly, to microwave antennas.
BACKGROUND OF THE INVENTION
The ridge horn antenna is a type of broadband antenna that is often used in communications systems. A ridge horn antenna generally includes ridges which carry electromagnetic energy from the signal source to the illumination area of the ridge horn antenna. An impedance transformer may be inserted between the ridges to match the input impedance of the antenna to the source. The antenna gain of the ridge horn antenna is typically higher than that of spiral and sinuous types of planar antennas, but generally less than most directional narrow beam antennas.
A reflector is often used to achieve a required level of gain for a highly directional antenna. A reflector antenna generally includes a reflector dish and a feed horn in one of many configurations. Two well known configurations of a feed horn antenna are the rectangular horn and cylindrical horn. In such configurations, the feed horn is a radiator mounted at the focal point of a reflector. Electromagnetic energy radiates from the feed horn to the metallic surface of the reflector dish from which it is reflected in a desired direction.
More specifically, a quad-ridge horn is an example of a ridge horn antenna and has a hollow conductive conduit usually having a circular cross section for propagation of microwaves between two points. The horn conduit may be formed of an electrically conductive material or of a non-conductive material that is plated or coated with an electrically conductive material. Moreover, to receive signals, horn antennas are dimensioned and flared to receive a concentration of low energy but discernable fields at one or more specific frequencies in the throat area of the horn.
A quad-ridge horn is dual-polarized and includes four ridges or tapered blades which aid in the propagation of the microwaves. Detectors are inserted or placed at the throat of the horn to receive the energy from the fields at the frequency or frequencies for which the horn has been designed. The horn is typically coupled to circuitry through orthogonal coaxial probes for input/output of Radio Frequency (RF) signals. Thus, external cables and connectors are necessary for transition to a planar distribution network.
Making an array of horns can be difficult because of the size requirements due to the RF input/output cabling, e.g. in higher frequency applications. Furthermore, soldering and micro-assembly during manufacture of the horn is difficult to automate resulting in higher costs and variable RF characteristics.
Additionally, some conventional dual-ridge horns with single polarization use microstrip feed lines or launches for transitions to circuitry. For example, U.S. Pat. No. 4,973,925 to Nusair et al., entitled “Double-Ridge Waveguide to Microstrip Coupling” discloses the use of modified ridges of a section of a double-ridge waveguide to match a microstrip circuit. Also, U.S. Pat. No. 4,157,550 to Reid et al., entitled “Microwave Detecting Device With Microstrip Feed Line” discloses the use of a slot in a waveguide to accommodate a microstrip feed line. However, in both patents, the microstrip circuit is positioned in the plane of the waveguide axis and the approaches are limited to single polarized dual-ridge waveguides/horns.
Additionally, U.S. Pat. No. 5,359,339 to Agrawal et al., entitled “Broadband Short-horn Antenna” discloses a horn array having a short-circuiting wall carrying a plurality of feed probes for the horns. Although the short-circuiting wall is mounted at the rear of the horn array, feed probes are used which may make it difficult to automate soldering and micro-assembly during manufacture of the horn array, resulting in higher costs and variable RF characteristics.
SUMMARY OF THE INVENTION
In view of the foregoing background, it is therefore an object of the invention to ease the manufacture and decrease the size requirements for a quad-ridge horn with dual polarization and/or for an array of quad-ridge horns.
This and other objects, features and advantages in accordance with the present invention are provided by an antenna device which includes a dual polarized quad-ridge antenna horn having an electrically conductive conduit with first and second opposite ends along a horn axis. Four electrically conductive ridges extend longitudinally on an inner side of the conductive conduit. A dielectric substrate is connected across the first end of the dual polarized quad-ridge antenna horn and transversely to the horn axis. Furthermore, an electrically conductive pattern is formed on the dielectric substrate and defines feed elements for the dual polarized quad-ridge antenna horn.
The feed elements for each antenna horn are preferably positioned orthogonal to each other on the dielectric substrate, and the electrically conductive pattern may further comprises portions corresponding to the electrically conductive conduit and the four electrically conductive ridges. Thus, the electrically conductive conduit and the four electrically conductive ridges are preferably connected to the corresponding portions of the electrically conductive pattern with an electrically conductive adhesive. Also, the dielectric substrate includes first and second opposite sides, and the electrically conductive pattern includes a first side conductive pattern on the first side of the dielectric substrate, and a second side conductive pattern on the second side of the dielectric substrate. The dual polarized quad-ridge antenna horn is secured to the first side of the dielectric substrate and electrically connected to the first side conductive pattern. Here, the electrically conductive pattern on the first and second sides may be connected together via conductors through in the dielectric substrate. Additionally, active circuits for the antenna device may be provided on the dielectric substrate and connected to the electrically conductive pattern.
Moreover, a phased array antenna may be formed from a plurality of antenna horns with the dielectric substrate connected across the first ends of the plurality of antenna horns and transversely to the horn axes. Here, the electrically conductive pattern on the dielectric substrate defines feed elements for each of the plurality of antenna horns. Because of the elimination of RF input/output cabling and the corresponding reduction in size, such a phased array antenna may be used in higher frequency applications. Furthermore, manufacture of the horn can be eased through automation resulting in lower costs and less variable RF characteristics.
Objects, features and advantages in accordance with the present invention are also provided by a method of making an antenna device including providing an antenna horn having first and second opposite ends along a horn axis; forming an electrically conductive pattern, defining at least one feed element for the antenna horn, on a dielectric substrate; and connecting the dielectric substrate across the first end of the antenna horn and transversely to the horn axis.
Also, a phased array antenna may be formed by providing a plurality of antenna horns, and forming the electrically conductive pattern to define feed elements for each of the plurality of antenna horns. The dielectric substrate is connected across the first ends of the plurality of antenna horns and transversely to the horn axes. Furthermore, each of the plurality of antenna horns may be a dual polarized quad-ridge horn each having an electrically conductive conduit and four electrically conductive ridges extending longitudinally on an inner side of the electrically conductive conduit. Here, the electrically conductive pattern preferably defines feed elements for each dual polarized quad-ridge horn, the feed element being preferably positioned orthogonal to each other on the dielectric substrate.
REFERENCES:
patent: 3714652 (1973-01-01), Grabowski et al.
patent: 4157550 (1979-06-01), Reid et al.
patent: 4278955 (1981-07-01),
Heckaman Douglas E.
Rief Gary A.
Schrimpf Robert J.
Allen Dyer Doppelt Milbrath & Gilchrist, P.A.
Harris Corporation
Le Hoang-anh
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