A 39-dBi Long Slot Array at K-band

In this communication, we introduce a high-gain antenna at K-band, covering the frequency range 17.3-21.5 GHz. The antenna is based on a long slot array fed by a parallel corporate feeding network (CFN). The CFN is tapered to reduce side lobe levels (SLL) in the radiating plane orthogonal to the long slots across the entire frequency band (SLL < −26 dB). A pillbox coupler serves as a quasi-optical system to convert cylindrical waves from the feeding rectangular waveguide to a guided field with a tapered amplitude and linear phase front to feed the CFN. The antenna is fabricated using computer numerically controlled (CNC) milling technology in aluminum to minimize losses. The antenna has a diameter of 630 mm and a thickness of 70 mm. The antenna exhibits a minimum measured realized gain of 39.7 dBi at 17.3 GHz.