This　article　reports　on　a　new　class　of　broadband　and　fully　3-D　printed　E-plane　coax-to-waveguide　transition　and　a　monolithically　3-D　printed　waveguide　magic-T　based　on　the　transition.　The　transition　is　constructed　by　a　section　of　air-filled　rectangular　coaxial　transmission　line　(TL)　that　is　placed　between　two　broadband　coax-to-waveguide　probe　transitions.　It　is　used　to　interconnect　the　magic-T＇s　sum　port　and　the　waveguide　T-junction.　The　incorporation　of　the　transition　reorients　all　the　waveguide　arms　of　the　magic-T　into　the　E-plane.　Some　X-band　prototypes　of　the　proposed　transition　and　the　magic-T　are　designed　and　implemented.　Polymer-based　additive　manufacturing　and　copper　electroplating　techniques　are　employed　to　monolithically　fabricate　each　prototype.　The　transition　and　the　magic-T　exhibit　broadband　and　low-loss　characteristics　from　8.2　to　12.4　GHz　with　the　measured　performance　well　matched　with　the　simulations.　In　addition,　the　power　handling　capability　(PHC),　including　the　peak　PHC　(PPHC)　and　the　average　PHC　(APHC),　of　the　magic-T　is　evaluated　by　simulations,　showing　that　the　proposed　magic-T　could　handle　100　W　of　APHC.　©　1963-2012　IEEE.