Design Method of Dual Band Antenna Composed of Unbalanced Fed Ultra Low Profile Inverted L Antenna

Abstract

The dual band antenna composed of the unbalanced fed ultra low profile inverted L antenna on the rectangular conducting plane is numerically analyzed. The antenna element is composed by the semi rigid coaxial cable. The parasitic wire is located above the inverted L antenna. The size of conducting plane is 30 mm by 70 mm. When the length of horizontal element of the inverted L antenna is 30.1 mm, and the length of parasitic element is 31 mm, the S11 less than -10dB is satisfied from 2.40 GHz to 2.50 GHz, 4.42 GHz to 4.58 GHz. The calculated directivity becomes 4.43 dBi at 2.45 GHz, and 7.76 dBi at 4.50 GHz. By changing the length and position of parasitic element, higher frequency becomes to 3.75 GHz.