Broadband surface-enhanced infrared absorption (SEIRA) spectroscopy is crucial for achieving high-sensitivity in the detection of complex analyte. A new design of Six-pointed Asterisk NanoAntenna (SANA) array is proposed to enhance signal-to-noise ratio of SEIRA spectroscopy. The SANA structure offers elevated design freedom in terms of resonance amplitude and frequency. The measurement data clearly demonstrates that our device has the most uniform resonance coverage over 390 cm ^-1. The broadband resonance uniformity directly benefits the signal-to-noise ratio enhancement across six fingerprints of alanine. Our SEIRA nanoantenna array design method serves as an effective approach for broadband and dense fingerprints detection. For example, it enables the simultaneous measurement of amide I and amide II, allowing for more comprehensive analysis of biomolecules.