A Compact Printed Dual-Band (915MHz/2.4GHz) Folded Monopole Antenna

Abstract

A compact printed dual-band folded monopole antenna has been proposed for the operation at 915MHz and 2.4GHz ISM bands. The dual resonance operation from a monopole antenna with a total length lesser than 0.2λ915MHz including a finite ground plane occupying 1/6th of the total antenna space is the main feature of the proposed antenna. Furthermore, the easier integration of the proposed dual-band antenna on the printed circuit board without using its ground plane is another important characteristic. The desired dual resonances were obtained by implementing a folded conductor pattern for the antenna’s main radiator along with two rectangular conductor stubs deployed at different positions along the main radiator on a 60 x 20 x 1mm3 FR4 substrate. The 915MHz resonance was caused by the folded conductor pattern of the main radiator with a stub located at its end while a shorter conductor segment was defined on the main radiator by placing the second rectangular stub at about 0.25λ2.4GHz caused the other resonance at 2.4GHz. The design of the proposed dual-band antenna was simulated and analyzed in ANSYS HFSS. The simulated return loss of about -18dB at both frequencies along with a peak realized gain of 3.2dB and 2.3dB were obtained at 915MHz and 2.4GHz respectively.