Modified Series-Fed Two-Dipole-Array Antenna With Reduced Size

In this letter, a modified series-fed two-dipole-array (STDA) antenna with reduced size is proposed for mobile communication applications. The proposed antenna consists of two modified dipole elements with different lengths and a modified ground plane, and these are serially connected through a coplanar strip (CPS) line. To reduce the lateral size of a conventional STDA antenna, rectangular patch-shaped top loading is employed for the two dipole elements, and a grooved ground plane is used by adding a patch at both ends of the ground plane. Tapered transitions are also used between the top-loading patches and CPS lines to improve the impedance matching of the antenna and, therefore, to increase the gain. A proposed antenna covering a frequency band of 1.7-2.7 GHz with a gain >5 dBi is designed and fabricated on an FR4 substrate. The total width of the fabricated prototype of the proposed antenna is reduced by approximately 14.3% compared to the conventional STDA, and it presents a 49.7% bandwidth in the range of 1.68-2.79 GHz and a stable gain of 5.86-6.13 dBi, which is similar to that of the conventional STDA antenna. Moreover, a front-to-back ratio is improved by 2.07-5.66 dB.