{"id":346467,"date":"2024-01-25T01:22:12","date_gmt":"2024-01-25T01:22:12","guid":{"rendered":"\/forum\/forums\/topic\/simulation-anomaly-in-frequency-selective-surface\/"},"modified":"2024-01-25T01:22:12","modified_gmt":"2024-01-25T01:22:12","slug":"simulation-anomaly-in-frequency-selective-surface","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/simulation-anomaly-in-frequency-selective-surface\/","title":{"rendered":"Simulation anomaly in frequency selective surface?"},"content":{"rendered":"<p>I&#8217;m trying to identify the source of a specific type of anomaly in the transmission (s21) parameter of a frequency selective surface. The anomoly can be seen at approximately 480 GHz below:&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" title=\"s21\" src=\"\/forum\/wp-content\/uploads\/sites\/2\/2024\/01\/25-01-2024-1706145373-s21.png\" alt=\"\" width=\"982\" height=\"302\"><\/p>\n<p>&nbsp;<\/p>\n<p>I&#8217;ve set up a model using periodic boundary conditions and Floquet ports to simulate a single unit cell of a low-pass filter. The model uses a &#8216;perfect conductor&#8217; for the material. Model is shown below:&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" title=\"Model\" src=\"\/forum\/wp-content\/uploads\/sites\/2\/2024\/01\/25-01-2024-1706145273-model.png\" alt=\"\" width=\"651\" height=\"265\"><\/p>\n<p>&nbsp;<\/p>\n<p>I&#8217;ve specified a &#8216;Broadband&#8217; solution type with 0.5% Maximum Delta S as a convergence criteria:&nbsp;<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" title=\"Solution\" src=\"\/forum\/wp-content\/uploads\/sites\/2\/2024\/01\/25-01-2024-1706145501-solution.png\" alt=\"\" width=\"537\" height=\"634\"><\/p>\n<p>&nbsp;<\/p>\n<p>The discrete sweep goes from 1GHz to 600 GHz in 1GHz increments:&nbsp;<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" title=\"Sweep\" src=\"\/forum\/wp-content\/uploads\/sites\/2\/2024\/01\/25-01-2024-1706145557-Sweep.png\" alt=\"\" width=\"432\" height=\"421\"><\/p>\n<p>&nbsp;<\/p>\n<p>I&#8217;ve verified that the mesh has met the convergence criteria:&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" title=\"convergence\" src=\"\/forum\/wp-content\/uploads\/sites\/2\/2024\/01\/25-01-2024-1706145631-convergence.png\" alt=\"\" width=\"479\" height=\"369\"><\/p>\n<p>&nbsp;<\/p>\n<p>I&#8217;ve simulated similar frequency selective surfaces with several different geometries (and therefore cutoff frequencies). I&#8217;ve noticed similar artifacts in nearly all of these simulations. I&#8217;d appreciate any help in identifying the cause of these anomolies.&nbsp;<\/p>\n","protected":false},"template":"","class_list":["post-346467","topic","type-topic","status-closed","hentry"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_subscription":["252359","1178"],"_bbp_author_ip":["23.206.193.150"]," _bbp_last_reply_id":["0"]," _bbp_likes_count":["0"],"_btv_view_count":["362"],"_bbp_topic_status":["unanswered"],"_bbp_topic_id":["346467"],"_bbp_forum_id":["27793"],"_bbp_engagement":["1178","252359"],"_bbp_voice_count":["2"],"_bbp_reply_count":["1"],"_bbp_last_reply_id":["346837"],"_bbp_last_active_id":["346837"],"_bbp_last_active_time":["2024-01-26 21:07:11"]},"test":"ixg90case-edu"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/346467","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\/346467\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=346467"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}