{"id":458085,"date":"2026-05-13T10:23:34","date_gmt":"2026-05-13T10:23:34","guid":{"rendered":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/s21-results-missing-in-100ghz-metamaterial-simulation-with-floquet-ports\/"},"modified":"2026-05-13T10:23:34","modified_gmt":"2026-05-13T10:23:34","slug":"s21-results-missing-in-100ghz-metamaterial-simulation-with-floquet-ports","status":"publish","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/s21-results-missing-in-100ghz-metamaterial-simulation-with-floquet-ports\/","title":{"rendered":"S21 results missing in 100GHz Metamaterial simulation with Floquet Ports"},"content":{"rendered":"<p>&lt;p&gt;Hello,&lt;\/p&gt;&lt;p&gt;I am a graduate student researching &#8220;Metamaterial Antenna-Integrated Quantum Well Optical Modulators&#8221; for the 100GHz band. I am currently facing an issue where S21 is not being output (or appears as zero) in my HFSS simulation, while S11 is plotted correctly.&lt;\/p&gt;&lt;p&gt;Simulation Setup:&lt;\/p&gt;&lt;p&gt;Frequency: 100GHz (W-band)&lt;\/p&gt;&lt;p&gt;Ports: Floquet Ports (Port 1 and Port 2)&lt;\/p&gt;&lt;p&gt;Boundaries: Primary\/Secondary (Master\/Slave) Periodic Boundary Conditions&lt;\/p&gt;&lt;p&gt;Structure: A metamaterial resonator (Meta-atom) coupled with a semiconductor waveguide (FACQW core layer).&lt;\/p&gt;&lt;p&gt;Current Issue:&lt;br&gt;Despite successfully running the analysis, only S11 data is available in the Results. S21 remains at zero or is missing from the plot options altogether.&lt;\/p&gt;&lt;p&gt;What I have tried:&lt;\/p&gt;&lt;p&gt;Benchmarking: I successfully reproduced the S-parameter results of a previous study using a similar setup with a Lithium Niobate (LN) substrate.&lt;\/p&gt;&lt;p&gt;Material Check: I suspected the high-dielectric waveguide might be the cause, but changing the waveguide material\/dimensions did not resolve the missing S21 issue.&lt;\/p&gt;&lt;p&gt;Port Modes: I have checked that both Floquet ports have the same number of modes defined.&lt;\/p&gt;&lt;p&gt;Questions:&lt;\/p&gt;&lt;p&gt;Could this be an issue with the &#8220;Post Processing&#8221; mode setup in the Floquet port settings?&lt;\/p&gt;&lt;p&gt;Are there specific conditions where S21 is not calculated even if the simulation completes without errors?&lt;\/p&gt;&lt;p&gt;Could the polarization setup between the two ports be causing an orthogonality issue that nullifies the transmission?&lt;\/p&gt;&lt;p&gt;<img decoding=\"async\" src=\"https:\/\/innovationspace.ansys.com\/forum\/wp-content\/uploads\/sites\/2\/2026\/05\/13-05-2026-1778667246-mceclip0.png\" \/>&lt;\/p&gt;&lt;p&gt;<img decoding=\"async\" src=\"https:\/\/innovationspace.ansys.com\/forum\/wp-content\/uploads\/sites\/2\/2026\/05\/13-05-2026-1778667266-mceclip1.png\" \/>&lt;\/p&gt;&lt;p&gt;<img decoding=\"async\" src=\"https:\/\/innovationspace.ansys.com\/forum\/wp-content\/uploads\/sites\/2\/2026\/05\/13-05-2026-1778667290-mceclip2.png\" \/>&lt;\/p&gt;&lt;p&gt;<img decoding=\"async\" src=\"https:\/\/innovationspace.ansys.com\/forum\/wp-content\/uploads\/sites\/2\/2026\/05\/13-05-2026-1778667313-mceclip3.png\" \/>&lt;\/p&gt;&lt;p&gt;&nbsp;&lt;\/p&gt;&lt;p&gt;<img decoding=\"async\" src=\"https:\/\/innovationspace.ansys.com\/forum\/wp-content\/uploads\/sites\/2\/2026\/05\/13-05-2026-1778667334-mceclip4.png\" \/>&lt;\/p&gt;&lt;p&gt;<img decoding=\"async\" src=\"https:\/\/innovationspace.ansys.com\/forum\/wp-content\/uploads\/sites\/2\/2026\/05\/13-05-2026-1778667362-mceclip5.png\" \/>&lt;\/p&gt;<\/p>\n","protected":false},"template":"","class_list":["post-458085","topic","type-topic","status-publish","hentry"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_forum_id":["27793"],"_bbp_topic_id":["458085"],"_bbp_author_ip":["133.34.34.49"],"_bbp_last_reply_id":["458256"],"_bbp_last_active_id":["458256"],"_bbp_last_active_time":["2026-05-15 12:15:25"],"_bbp_reply_count":["7"],"_bbp_reply_count_hidden":["0"],"_bbp_voice_count":["2"],"_bbp_engagement":["686875","469978"],"_btv_view_count":["51"],"_bbp_topic_status":["unanswered"],"_bbp_subscription":["469978","686875"]},"test":"arakawa-taro-vjynu-ac-jp"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/458085","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics"}],"about":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/types\/topic"}],"version-history":[{"count":0,"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/458085\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=458085"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}