Vol. 10 No 1 February 2002
Conical Horn with RC Transit (W-Band)
The conical horn is the primary feed for the lens/reflector antenna system and is used as a stand-alone antenna system. The wavelength at W-band is much lower than that of the microwaves thus requiring tight tolerances to achieve the desired performance. The conical horn terminates with a circulatory cross-section and rectangular wave guides are generally used to connect the Tx/Rx system. A rectangular-to-circular transition is thus required to connect the system for efficient transfer of power.
The desired performance has been achieved within an accuracy of +12 micrometre on waveguide, and surface finish of 0.25 micrometre Ra (CH8 as per VDI 3400). Electrolytic copper has been used as a tool electrode material both for roughing (high material removal rate) using down cycle and micro-finishing (for surface finish) using orbital cycle. Machine setting parameters, like peak current, on-time/off-time, spark gap and secondary parameters (B,R,U,SV) are optimised to achieve the desired results within reasonable time limit. The horn has been electronically tested and the VSWR of 1.15 has been achieved.