COMPACT ULTRA WIDEBAND MICROSTRIP ANTENNA WITH MULTIPLE NOTCHES
In this paper, a new compact circular monopole ultrawideband antenna with multiple narrow bands notched is proposed, which is implemented by using the existing techniques, such as loading a L-type band-stop filter, inserting a split ring resonator (SRR), and the method we proposed that connecting L branches on the radiation disk. Four sharp notches at 2.4GHz, 3.5 GHz, 5.5 GHz, and 7.6 GHz are achieved separately. The measured VSWR shows a good agreement with the simulation results. The radiation patterns are obtained from Ansoft HFSS simulations and verified by CST Microwave Studio. The results prove that this kind of antenna can be applied in the UWB communication systems to avoid interference with other wireless systems, such as the 2.4GHz WLAN, 3.5 GHz WiMax, and 5.8 GHz WLAN etc. The parameters determining the antenna’s band notched characteristic are discussed.
The commercial usages of frequency band from 3.1 GHz to 10.6 GHz, was approved by Federal Communications Commission (FCC) in 2002 [1]. To satisfy such requirement various ultra-wideband antennas have been studied [2–16]. But the frequency range for UWB systems will cause interference to the existing wireless communication systems, so the UWB antennas with a band-notched characteristic are required. To satisfy such requirement various ultra-wideband antennas with notched band have been studied [17–26]. The slot was used in [17–21] to achieve the band-notched characteristic. The method of add the parasitic patch was used in [22, 23]. And Ren at al. [24] proposed an inverted-T structure. An L-type band-stop filter was322 Yin et al. first proposed in [27], and was used in [25, 26] to produce the bandnotched characteristic in their ultra-wideband antennas. But most of the antennas can generate no more than two notched bands. In the paper, we present a new compact circular monopole ultrawide band antenna with four narrow bands notched, which is implemented by using the existing techniques, such as loading a L-type band-stop filter [25, 26], inserting a split ring resonator (SRR), and the method we proposed that connecting L branches on the radiation disk. Details of the antenna design are described. And the antenna was fabricated by a standard printed circuit board (PCB) technology. The measured VSWR shows a good agreement with the simulation results. The radiation patterns are obtained from Ansoft HFSS simulations, which are based on the Finite Element Method (FEM), and verified by CST Microwave Studio based on the finite integration method. All of the results certify that the antenna is a promising candidate for UWB communication systems to avoid interference with other wireless systems.
We first selected a normal printed circular disk monopole antenna, which can cover the frequency range from 3.1 GHz to 10.6 GHz for VSWR ≤ 2. The substrate has a relative permittivity of 2.65 and a thickness of 0.5 mm. We selected three frequency points 2.4GHz, 3.5 GHz, and 5.5 GHz as center frequencies of the stopbands, so the antenna will not interfere with the other wireless communications systems, such as 2.4GHz WLAN, 3.5 GHz WiMax, and 5.8 GHz WLAN systems.
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