Millimeter wave phased array systems with ring slot radiator element

• US 20060033671A1
• Filed: 08/11/2004
• Published: 02/16/2006
• Est. Priority Date: 08/11/2004
• Status: Active Grant

• Current Assignee: Northrop Grumman Systems Corporation (Northrop Grumman Corporation)
• Original Assignee: Northrop Grumman Corporation
• Inventors: Rivera, Juan, Chan, Steven S., Wu, Te Kao, Bhattacharyya, Arun, Metzen, Phillip L.
• Granted Patent: US 7,053,847 B2
• Time in Patent Office: Days
• US Class Current: 343/769
• CPC Class Codes: H01Q 13/106 Microstrip slot antennas patch antenna elements H01Q9/0407
• CPC Class Codes: H01Q 21/0087 Apparatus or processes specially adapted for manufacturing antenna arrays manufacturing waveguides H01P11/00
• CPC Class Codes: H01Q 21/0093 Monolithic arrays
• CPC Class Codes: H01Q 21/064 using horn or slot aerials slotted waveguides arrays H01Q21/005

Abstract

A phased array antenna structure capable of operation at millimeter-wave frequencies and having multiple ring slot radiator elements (10). The RF feed structure for each radiator element includes a feed via (28) extending part-way through a multi-layer structure (FIG. 3) on which the radiator elements (10) are formed and a strip line feed probe (30) extending from the via (28) toward the radiator element. A key feature facilitating high-frequency operation is the inclusion of multiple mode suppressors (32) surrounding the via (28) and providing a smooth transition from a coaxial mode of RF transmission to a strip line mode of RF transmission. The feed probe (30) is tailored to provide either a narrow-band or a wideband frequency characteristic.

Claims

1. A ring slot radiator structure for use in a phased array antenna system, the ring slot radiator structure comprising:

a dielectric substrate, having a top face and a bottom face;

a conductive layer formed over the top face of the substrate and having an annular gap that in part defines a radiator element;

a conductive feed via extending part-way through the substrate in a direction normal to the conductive layer, to transmit radio-frequency (RF) energy from a location located at the bottom of the substrate to transition point located outside the annular gap in the conductive layer and spaced beneath the conductive layer;

a strip line feed probe extending from the transition point in a generally radial direction parallel to the conductive layer and at least partially across the annual gap; and

a plurality of mode suppressor posts extending through the substrate in a direction parallel to the conductive feed via and spaced in a generally uniform array around the conductive feed via;

wherein the plurality of mode suppressor posts effect a smooth transition from a coaxial mode of transmission through the conductive feed via to a strip line mode of transmission along the strip line feed probe that couples RF energy to the ring slot radiator.

2. A ring slot radiator structure as defined in claim 1, and further comprising another plurality of mode suppressors, also extending in a direction normal to the conductive surface, and spaced about and outside the annular gap to effect better isolation of the ring slot radiator element from other neighboring elements.

3. A ring slot radiator structure as defined in claim 1, wherein:

the strip line feed probe is generally uniform in width and extends fully across the annular gap toward the geometric center of the annular gap; and

the ring slot radiator structure has a relatively narrow bandwidth in the order of 1%.

4. A ring slot radiator structure as defined in claim 1, wherein:

the strip line feed probe comprises a first section of uniform width extending from the transition point to a point near the outer diameter of the annular gap, and a contiguous transition section of increased width extending part-way across the annular gap; and

the ring slot radiator structure has an increased bandwidth in the order of 10%.

5. A miniature phased array antenna system capable of operation at millimeter-wave frequencies and formed as a unitary structure, comprising:

a multilayer structure having an upper face from which radiation is transmitted in a transmit mode of operation and which receives radiation in a receive mode of operation, and a lower face to accommodate radio-frequency (RF) feed and control circuitry;

a conductive layer formed over the top face of the substrate and having a plurality of annular gaps formed in a geometric array, wherein each annular gap in part defines one of a plurality of ring slot radiator elements;

an equal plurality of conductive feed vias extending part-way through the multi-layer structure in a direction normal to the conductive layer, each capable of transmitting radio-frequency (RF) energy from a location located at the bottom of the substrate to transition point located outside one of the annular gaps in the conductive layer and spaced beneath the conductive layer;

an equal plurality of strip line feed probes, each extending from the transition point associate with one of the plurality of radiator elements in a generally radial direction with respect to its annular gap, parallel to the conductive layer and at least partially across the annual gap;

an RF divider/combiner, integrated into the multi-layer structure and coupled to each of the conductive feed vias and to an RF transmitter/receiver connector; and

an equal plurality of sets of mode suppressor posts, each set being associated with a corresponding one of the conductive feed vias, and extending through the multi-layer structure in a direction parallel to the conductive feed via and spaced in a generally uniform array around the conductive feed via;

wherein each set of mode suppressor posts effects a smooth transition from a coaxial mode of transmission through the conductive feed via to a strip line mode of transmission along the strip line feed probe that couples RF energy to the ring slot radiator.

6. A miniature phased array antenna system as defined in claim 5, and further comprising an additional equal plurality of sets of mode suppressors, also extending in a direction normal to the conductive surface, the mode suppressors in each set being spaced about and outside the annular gap of a corresponding ring gap radiator element, to effect better isolation of each ring slot radiator element from the other neighboring elements.

7. A miniature phased array antenna system as defined in claim 5, wherein:

each of the strip line feed probes is of generally uniform width and extends fully across the annular gap toward the geometric center of the annular gap; and

the antenna system has a relatively narrow bandwidth in the order of 1%. 8. A miniature phased array antenna system as defined in claim 5, wherein;

each of the strip line feed probes comprises a first section of uniform width extending from the transition point to a point near the outer diameter of the annular gap, and a contiguous transition section of increased width extending part-way across the annular gap; and

the antenna system has an increased bandwidth in the order of 10%.