A multiband monopole antenna with double square slots and capacitive CPW feed for LTE, WiMAX and WLAN systems

This paper proposes a multiband monopole antenna with double square slots and capacitive CPW (CCPW) feed for applications in LTE, WiMAX and WLAN systems. The CCPW feed can control harmonic frequencies as desired and reduce size from ideal CPW length of λ/2 to only λ/8, while the slot technique can make return loss less than -10 dB and increase extension gain of the proposed antenna. The designed antenna has been operated at 1.8 GHz, 3.5 GHz, 5.5GHz for GSM, WiMAX and WLAN systems, respectively. The results show that the return losses are less than -10 dB at all frequency bands. The pattern is omni-directional and extension gains of all required bands are 2.45, 1.35 and 2.5dBi, respectively. This antenna was designed and implemented on FR-4 PCB. The experimental results of the fabricated antenna agree very well with simulation expectations using IE3D package.