James Roger Baker-Jarvis (né Baker; February 8, 1950 — December 31, 2011) was an American applied physicist and metrologist who was a research scientist at the Electromagnetics Division at National Institute of Standards and Technology (NIST).
His post-doctoral work concerned dielectric measurements and electromagnetic fields in lossy media.
In 1989, he joined National Institute of Standards and Technology (NIST), where he spent the remainder of his career and was the leader of Electromagnetic Properties of Materials Project.
[1][2] Baker-Jarvis' research work at NIST focused on microwave dielectric properties of materials and nondestructive evaluation.
[2] ASTM Standard 5568 for dielectric metrology techniques was largely based on his work on coaxial cable measurements.