Capacitively Coupled Microstrip Comb-Line Array Antennas for Millimeter-Wave Applications

This letter proposes a novel capacitively coupled microstrip comb-line (CCMCA) array antenna for millimeter-wave band applications. The proposed antenna has the advantages of low profile, low cost, and ease of fabrication for the millimeter-wave band. By adjusting the gaps between the radiating strips and feeding line, an antenna with low sidelobe level can easily be designed. To verify the suitability of the proposed antenna for millimeter-wave applications, two arrays (1 × 18 and 4 × 18) were designed and developed at the design frequency of 79 GHz. The measured results show good agreement with the simulated ones in terms of reflection characteristics and radiation patterns. In addition, the CCMCA antenna has stable beam direction even with frequency change, compared to a conventional series-fed microstrip rectangular patch array antenna.