Choon S Lee

US Patent:

6362785, Mar 26, 2002

Filed:

Oct 29, 1999

Appl. No.:

09/430258

Inventors:

Vahakn Nalbandian - Ocean NJ
Choon Sae Lee - Dallas TX

Assignee:

The United States of America as repesented by the Secretary of the Army - Washington DC

International Classification:

H01Q 138

US Classification:

343700MS, 343846

Abstract:

A first and a second conductive patch of a compact cylindrical microstrip antenna are connected at a junction point to shorten the length of the impedance transition from one edge, where the wave impedance vanishes, to the other patch edge, where the impedance becomes very large. The second conductive patch is wider than the first conductive patch and one end of the first conductive patch is shorted with the ground plane. The effective impedance to be satisfied by the narrower strip at the junction is greatly reduced by the presence of the junction of two different patches, which substantially decreases the size of the antenna at a given operation frequency.

US Patent:

6509873, Jan 21, 2003

Filed:

Oct 16, 2000

Appl. No.:

09/688419

Inventors:

Vahakn Nalbandian - Ocean NJ
Choon S. Lee - Dallas TX

Assignee:

The United States of America as represented by the Secretary of the Army - Washington DC

International Classification:

H01Q 136

US Classification:

343700MS, 343731, 343769

Abstract:

The present invention is an antenna comprising a microstrip having upper and lower layers for producing leaky wave radiation. Circularly shaped patches are located on the two layers for circularly polarizing the leaky wave radiation. The present invention provides a microstrip antenna that can produce wideband, circularly polarized radiation. The antenna, therefore, is a compact, low cost, rugged, conformal, planar, and circularly polarized microstrip antenna. The antenna combines the advantages of wideband circularly polarized radiation with the advantages of lightweight, low profile, low cost, and planar microstrip antennas.

US Patent:

6693595, Feb 17, 2004

Filed:

Apr 25, 2002

Appl. No.:

10/131990

Inventors:

Choon Sae Lee - Dallas TX

Assignee:

Southern Methodist University - Dallas TX

International Classification:

H01Q 2120

US Classification:

343700MS, 343844

Abstract:

A microstrip antenna has first and second cylindrically-shaped dielectric layers having first sides secured together with an array of conducting strips conformally interposed therebetween, the strips being spaced to define a slot between each pair of adjacent strips. A conductive ground plane is disposed on an interior second side of the first dielectric layer, and an array of spaced apart radiating patches are conformally disposed on an exterior second side of the second dielectric layer, each of which patches is positioned over a corresponding slot. Responsive to electromagnetic energy, a high-order standing wave is induced in the antenna and a directed beam is transmitted from and/or received into the antenna.

US Patent:

6839028, Jan 4, 2005

Filed:

Aug 9, 2002

Appl. No.:

10/214746

Inventors:

Choon Sae Lee - Dallas TX, US

Assignee:

Southern Methodist University - Dallas TX

International Classification:

H01Q 124

US Classification:

343700MS, 343824, 343830

Abstract:

An apparatus and method to reduce the size of a microstrip antenna without sacrificing antenna efficiency too much are described. The antenna structure includes discontinuity of strip width in the middle of the antenna patch to reduce the size of the antenna at a given resonant frequency. The antenna structure further includes a plurality of patches of differing widths connected to each other at junctions. The junctions are placed symmetrically to ensure maximum radiation at the boresight and also to further reduce cross-polarization levels. A coaxial feed is connected at a predetermined location near the center of a patch, having a narrower width, in order to match the input impedance of the antenna to the coaxial feed.

US Patent:

6987154, Jan 17, 2006

Filed:

Feb 19, 2003

Appl. No.:

10/371195

Inventors:

Choon Woo Lee - Pasadena CA, US
Isaac M. Rutenberg - Pasadena CA, US
Robert H. Grubbs - South Pasadena CA, US

Assignee:

California Institute of Technology - Pasadena CA

International Classification:

C08F 4/44

US Classification:

526161, 526172, 585511, 585514, 585523, 560205, 562598

Abstract:

This invention relates generally to synthetic procedures that include the step of ring-opening metathesis of cyclic olefins and reaction with an acyclic diene co-reactant to produce regularly repeating A,B-alternating olefin polymers. The A,B-alternating polymers are produced by varying reaction conditions and/or reactant proportions and using only two types of olefin metathesis (ring-opening and cross) to provide regularly repeating ABAB. . . etc. polymers via ring-opening metathesis polymerization (ROMP). More particularly, the invention pertains to synthesis of A,B-alternating olefin polymers via olefin metathesis reactions using a Group 8 transition metal complex as the metathesis catalyst. Polymers provided herein have utility in a variety of fields, including not only polymer chemistry per se, but also in the pharmaceutical, biomedical, and packaging industries where the structure and properties of polymers need to be tightly controlled.

US Patent:

7034096, Apr 25, 2006

Filed:

Feb 19, 2003

Appl. No.:

10/371196

Inventors:

Choon Woo Lee - Pasadena CA, US
Hyunjin M. Kim - San Ramon CA, US
Robert H. Grubbs - South Pasadena CA, US

Assignee:

California Institute of Technology - Pasadena CA

International Classification:

C08F 4/44
B01J 31/38

US Classification:

526336, 526171, 526172, 502152, 502155

Abstract:

This invention relates generally to synthetic procedures that include the step of ring-opening metathesis of cyclic olefins and reaction with an acyclic diene co-reactant to produce olefin macrocycles by ring expansion, or alternatively. The ring expansion of the cyclic olefin is provided by three types of sequential olefin metathesis (ring-opening, cross, and ring-closing olefin metathesis). More particularly, the invention pertains to synthesis of olefin macrocycles via olefin metathesis reactions using a Group 8 transition metal complex as the metathesis catalyst. Macrocycles provided herein have a variety of uses in the pharmaceutical, biomedical, organic synthesis and chemical industries, such as the production of crown ethers that are useful as metal complexing species.

US Patent:

7079077, Jul 18, 2006

Filed:

Feb 2, 2004

Appl. No.:

10/770540

Inventors:

Choon Sae Lee - Dallas TX, US

Assignee:

Southern Methodist University - Dallas TX

International Classification:

H01Q 1/38

US Classification:

343700MS, 343846

Abstract:

A wireless communication device includes an antenna configured with two conductive elements separated by an insulating medium providing a separation distance. One conductive element is a ground plane and the other is a microstrip line. The microstrip line and the ground plane exhibit a characteristic impedance that may vary along the length of the microstrip line. The separation distance of the microstrip line from the ground plane is changed to reduce the resonant frequency of the microstrip line. A second microstrip line with an open end and another end shorted to the ground plane is operative to prevent RF current from flowing on the backside of the ground plane. A backside of the ground plane and the second microstrip line may be covered with a lossy magnetic medium to reduce the near field in the space above the backside of the ground plane.

US Patent:

7205944, Apr 17, 2007

Filed:

Oct 20, 2005

Appl. No.:

11/254432

Inventors:

Choon Sae Lee - Dallas TX, US

Assignee:

Southern Methodist University - Dallas TX

International Classification:

H01Q 1/38
H01Q 1/48

US Classification:

343700MS, 343846

Abstract:

A wireless communication device includes an antenna configured with two conductive elements separated by an insulating medium. One conductive element is a ground plane and the other is a microstrip line. The ground plane is formed with a bend proximate an end. The microstrip line and the ground plane exhibit a characteristic impedance that may vary along the length of the microstrip line. The separation distance of the microstrip line from the ground plane is changed to reduce the resonant frequency of the microstrip line. A second microstrip line with an open end and another end shorted to the ground plane is operative to prevent RF current from flowing on the backside of the ground plane. A backside of the ground plane and the second microstrip line may be covered with a lossy magnetic medium to reduce the near field above the backside of the ground plane.