S21 measurements of the prototype 64 MHz PSA recorded from the network analyzer, demonstrating both narrow- and broadband decoupling in (a and b) the SW-PSA and (c and d) the TW-PSA. Part a is the S21 of an unloaded, shorted λ/4 strip pair of the SW-PSA. Although broadband decoupling of 30–40 dB is evident, narrow-band decoupling at resonance cannot be seen due to the open circuit at the input. b: The S21 when the shorted λ/4 strip pair of the SW-PSA is loaded. The load causes a phase shift, revealing the narrow-band decoupling. c: The S21 of an unloaded, matched λ/2 strip pair of the TW-PSA. d: The S21 of the matched λ/2 strip pair of the TW-PSA when it is loaded. The SW-PSA has a much better performance than the TW-PSA when it is loaded (b vs. d).