Anotace:
A dual band antenna based on the square planar dipole structure with interdigital capacitors is proposed. With this technique, the harmonic frequency band can be controlled as desired. The dipole element is constructed using two square copper plates. The size of antenna is 21.6 cm x 13.8 cm. The bandwidths of the proposed antenna are 170MHz (1.71-1.88GHz) and 200MHz (5.15-5.35GHz), while the gains are 10 dB and 8 dB, respectively. To increase the antenna gain, the array antenna composing of the two designed dipoles is studied. The size of array antenna is 21.6 cm x 24.4 cm. The improved gains of 13.1 dB for the first band and 10.1 dB for the second band are obtained. The array antenna with four designed dipoles is also investigated. The high gains of 16.8 dB for the first band and 12.6 dB for the second band are obtained. The proposed array antennas have higher gains compared with the conventional array antennas with the same element numbers. Therefore, the proposed antennas are suitably used for LTE and WLAN base stations.