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Jason
087a0563c0
Daisy-chain validation for 2-layer 0.508 mm RO4350B stackup. Row of 8 patches edge-connected via 8.0 mm microstrip segments (pitch 14.95 mm matches old Gerber). With direct edge feed on patch 0 (no inset; inset would drop the row input Z to ~6 Ω), the natural input impedance at the operating mode is ~80 Ω, close enough to 50 Ω for direct match without a quarter-wave transformer. Topology behaves as a finite periodic resonator with N=8 modes (~0.5 GHz spacing) and a stopband centered on the patch self-resonance. Operating point is the top-below-stopband mode at 10.56 GHz: S11 = -22.5 dB, Zin = 79.9 - j3 Ω. -10 dB BW spans 10.51-10.61 GHz (100 MHz), covering the 10.510-10.530 GHz chirp band with S11 = -10.4 to -14.6 dB across that interval. Mesh sensitivity: sanity profile (lambda/18) gave a misleading deepest-dip at 11.4 GHz; balanced (lambda/25) is required to land the operating-mode characterization correctly. PROFILE=balanced is now the documented run mode.