Broadband Corrugated Horn Array with Direct Machined Fabrication

We have developed a broadband corrugated horn in the 120–270 GHz and a horn array in the 80–180 GHz bands. The geometry of corrugations is so simple that the horn array can be directly machined from a bulk of aluminum with an end mill. The cross polarization and near sidelobe levels are less than $-$ 20 and $-$ 30 dB, respectively. The return loss is less than $-$ 15 dB in most design frequency bands, and the beam pattern is symmetric. The beam pattern and the return loss are measured in the 120–170 GHz range at room temperature. They are in good agreement with the simulation. It is possible to reduce reflection at the aperture surface and to reduce the weight by carving the unnecessary part. This design provides an octave bandwidth of the corrugated horn array at reasonable machining time.