We report the development of a sensitive carbon nanotube (CNT) infrared detector whose signals are boosted by nanoantenna-like features. This assembly is fabricated using nanoassembly of CNTs and a standard photolithographic process, together with nanoantenna-like features that are designed to create a resonance structure necessary to boost the electric field intensity at the CNT sensor. A novel approach is employed to find the near-field effect of the antenna. As a result, these effects are verified and demonstrated experimentally in this paper. The first experimental demonstration of a practical infrared device with nanoantenna-like structures is reported; it shows that the photocurrent is increased by an order of magnitude. The proposed fabrication and design process enables a ready integration of resonance structures into the manufacture of infrared devices, and opens the possibility of developing high fidelity infrared sensors with wide sensing range.