A.Lounine, T.Higo H60VG3K1 Couplers Design. MDK-2001 CERN Switzerland

Input Coupler Output Coupler r = 0.5 10.12 10.35 r = 0.5 T0m= 5 Matching Cell r = 0.5 T0m= 5 2A0m= 15.52 2B1m= 24.2 T53m= 4.8 2A53m= 13.82 T1= 4.53732 2A1= 10.7947 2B53m= 23.2 Matching Cell All dimensions are at 20C Calculation frequency is 11.429 GHz

Equidistant Manual Mesh Generation Tetrahedras ~ 300.000 Azimuth rotation step = 2 degree ! Automatic ANSOFT mesh generator produces too much nonuniform mesh; ! As a result – poor convergency, poor field’s output

Tipical HFSS simulation for output coupler * E[V/m] is normalized for 1 Wt input power (a quarter geometry!)

Output Coupler Surface Fields ~3.5% iris field enhancement Surface path * E[V/m] is normalized for 1 Wt input power (a quarter geometry!)

N.Kroll Method of Reflection and Phase Advance Simulation Results Input Coupler Output Coupler

Network Analizer Experemental Setup S11, S21 RF Load HP 8510C Matching cell Reflection = S11 + S12 S22, S12

Input Coupler. HFSS&Experemental Results* * Experimental results are shifted to the calculation conditions (20C, vacuum)

Output Coupler. HFSS&Experemental Results* * Experimental results are shifted to calculation conditions (20C, vacuum) ** Due to technical mistake the measurement was done with wrong RF-load diameter

Base Parameters Tolerances, HFSS Simulations Output Coupler. Base Parameters Tolerances, HFSS Simulations

Final Remarks. H60VG3 is low group velocity structure , therefore couplers bandwidth is very narrow. The mesh parameters are very critical to final results. The 3D Mesh parameters were obtained from 2D analog. The phase advance was strictly cheked at each calculation step (<0.5 degree). Hook-Jeevs method + frequency sweep were used for couplers optimization. The measurement results are in good agreement with the calculated ones. The most sensitive dimension is B (outer radius). The accuracy of Bn dimensions should be better then 2 μm.