English: A high power microwavedummy load used for testing waveguide systems. A dummy load is a waveguide termination that absorbs all the microwave power applied to it without reflecting any, converting the microwaves to heat. It has heatsink fins to dissipate the heat. The flange visible on the righthand side is attached to a waveguide.
This 1952 issue of Tele-Tech magazine would have the copyright renewed in 1980. Online page scans of the Catalog of Copyright Entries, published by the US Copyright Office can be found here. Search of the Renewals for Periodicals for 1979, 1980, and 1981 show no renewal entries for Tele-Tech. Therefore the copyright was not renewed and it is in the public domain.
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.