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1924

Society: IEEEMain Category: ElectricEra: 1920-1929DateCreated: 1924Tohoku University Sendai-shiCountry: JapanWebsite: http://www.ieeeghn.org/wiki/index.php/Milestones:Directive_Short_Wave_Antenna,_1924Creator: Hidetsugu Yagi, Uda, Shintaro
Beginning in 1924, Professor Hidetsugu Yagi and his assistant, Shintaro Uda, designed and constructed a sensitive and highly-directional antenna using closely-coupled parasitic elements. The antenna, which is effective in the higher-frequency ranges, has been important for radar, television, and amateur radio. The antenna system, using a driven element with closely coupled parasitics (usually a reflector and one or more directors) for short-wave work, was first described by S. Uda, a professor at Tohuku University in Japan, in 1926, in the IEEJ (Japan). A colleague, Professor H.
YearAdded:
1995
Image Credit: Courtesy IEEEImage Caption: The Yagi-Uda directive short wave antennaEra_date_from: 1924
Bay City Walking Dredge
Society: ASMEMain Category: MechanicalSub Category: Materials Handling & ExcavationEra: 1920-1929DateCreated: 1924Collier-Seminole State ParkNaplesState: FLZip: 34114Country: USAWebsite: http://www.asme.org/about-asme/history/landmarks/topics-m-z/materials-handling-and-excavation/-172-bay-city-walking-dredge-%281924%29Creator: Bay City Dredge Works, Anderson, Vincent

Built by the Bay City Dredge Works of Bay City, Michigan, this dredge was used to construct a portion of US 41 called the Tamiami Trail, which connected Tampa with Miami through the Everglades and Big Cypress Swamp. The last remaining display of walking dredges (of some 145 walking machines), it has a unique propulsion design enabling the dredge to cope with drainage problems in a wetlands environment.

YearAdded:
1994
Image Credit: Courtesy Wikipedia/Ebyabe (CC BY-SA 3.0)Image Caption: The Bay City Walking Dredge as it sits in Collier-Seminole State ParkEra_date_from: 1924
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