Low-Cost, Direct-Fed Slot Antenna Built in Metal Cover of Notebook Computer for 2.4-/5.2-/5.8-GHz WLAN Operation

The slot antenna has been utilized for some recent notebook computers on the market. The FR4 substrates are usually required to print the metal patterns for coupled-feeding the 2.4 GHz (2400-2484 MHz) slot and also for contributing the 5.2 GHz (5150-5350 MHz) and 5.8 GHz (5725-5825 MHz) bands. This communication presents a simple, direct-fed slot antenna with a low profile of 7 mm to the top edge of the metal cover for 2.4-/5.2-/5.8-GHz WLAN operation. The antenna design did not require any substrate and can be implemented directly in the metal cover of a notebook computer at low cost. The design comprised two parallel-connected, 0.5-wavelength-slot portions, formed in a linear structure of length 79 mm and constant width 2 mm, and fed by a common antenna feed port using a mini-coaxial cable. The larger slot generated a 0.5-wavelength resonant mode in the 2.4-GHz band and a 1-wavelength mode for 5.2-GHz operation. The smaller slot operated in a 0.5-wavelength resonant mode, which covered the 5.8-GHz band. With a matching inductor properly set in the slot, good input impedance over the 2.4-, 5.2-, and 5.8-GHz bands can be attained.