Granted Patent
Utility
US 4,680,561 · App. 06/738,952
Microwave waveguide filter having a metal plate which includes a resonant aperture therein
Inventor:
Tadao Shirai
Patented Case
View Patent ↗
Granted: Jul 14, 1987
Filed: May 29, 1985
Inventor
Tadao Shirai
Assignee (at issue)
NEC CORPORATION
This patent predates the USPTO's electronic file wrapper — prosecution documents from this era exist only in the Patent Office's paper records. A certified copy of the file history can be ordered from the USPTO's paper archives.