A Coaxial TEM Cell for Direct Measurement of UHF Artificial Magnetic Conductors [AMTA Corner]

We have demonstrated a coaxial TEM (transverse electromagnetic wave) cell for direct measurement of artificial magnetic conductors (AMCs) in the VHF-UHF range. The advantages of the coaxial TEM cell are 1) it is a compact, bench-top device; and 2) it provides rapid, direct measurement of artificial-magnetic-conductor reflection response over a broad frequency range. We present measurements of various artificial-magnetic-conductor structures measured in the coaxial TEM cell, including 1) fixed-response, capacitor-loaded artificial magnetic conductors; 2) tunable varactor-loaded artificial magnetic conductors; and 3) wideband, tunable artificial magnetic conductors loaded with non-Foster, negative-inductance circuits. The measurements of the various artificial magnetic conductors were consistent with simulations. The coaxial TEM cell detailed here was 50 cm long with a 10.4 in diameter at the DUT, tapering to an N connector at the feed port. It was single-moded below 500 MHz. The design can be scaled to extend to other frequencies and other artificial-magnetic-conductor geometries.