Though I see no information about copyright in this RCA magazine, a copyright renewal search was done at copyright.gov for the title Radio Age. There were no listings. There is no evidence of copyright being claimed on this material.
Note that it may still be copyrighted in jurisdictions that do not apply the rule of the shorter term for US works (depending on the date of the author's death), such as Canada (70 years p.m.a.), Mainland China (50 years p.m.a., not Hong Kong or Macao), Germany (70 years p.m.a.), Mexico (100 years p.m.a.), Switzerland (70 years p.m.a.), and other countries with individual treaties.
{{Information |Description=Photo of David Sarnoff with the first RCA videotape machine in 1954. |Source=[http://archive.org/stream/radioageresearch195354newyrich#page/n151/mode/2up page 2] Radio Age |Date=[http://archive.org/stream/radioageresearch1953...