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Advances in radio wave transmission and KGW’s own company history brought about changes to tower structures on the site in the 1930s and 1940s.
When KGW acquired a sister station in 1933 by leasing KEX-AM from the Western Broadcasting Company (a subsidiary of NBC), it moved the KEX transmission equipment to KGW’s transmitter building. In 1934, KEX erected a 300-foot wooden mast tower, which later was knocked down during the 1948 Vanport flood.
 In 1937, KGW replaced one of its 300-foot-high antennas with a 625-foot-tall, foot-guyed Truscon radiator tower (later known as the west tower). The 1937 west tower remained standing on its original site until Dec. 26, 2000, when it was toppled by the Port for maintenance and safety reasons (such as it being in the flight path of Portland International Airport), and to begin the process of wetlands restoration.
KGW replaced the other 1931 tower in 1941-42 with a 625-foot vertical tower, which had a directional antenna. Following the destruction of this tower by the great 1948 Columbia River flood, a new east tower was erected on the same site in late 1948 or early 1949. A fresh coat of paint and lights, to serve as a warning to airplane pilots, were added to both towers in the 1950s. The 1949 east tower remained standing until Dec. 26, 2000, when it too was removed by the Port for maintenance and safety reasons, and to prepare the property for wetlands restoration.
A main operational component of each KGW antenna was a buried copper grid system consisting of 120 equally-spaced, 800-foot-long copper wires that radiated from the base of each antenna tower. The radials from the two towers were one and one-fourth times as long as the height of the towers and met at a common copper cord, where they were banded together. The copper radials helped extend the transmitting power of the antennas. KGW replaced the grid system for both antenna towers in 1965.
In the late 1980s, a KGW engineer installed new vertical copper grounding rods at the base of the east and west towers. They were implanted eight feet into the ground and served as replacements for heavy copper screens that had deteriorated over the years.
As part of the Port's wetlands restoration effort, the grounding rods and wires were removed in December 2000.
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