This article presents a novel planar monopole antenna with circular polarization. The 3‐dB axial ratio (AR) is achieved by: shifting a vertical monopole to the left edge of the substrate in conjunction with a laterally inverted L‐shaped ground plane. When viewed from the top, the antenna resembles an uneven T‐shaped structure rotated at 90°. Measurement results show that; a 3‐dB AR bandwidth is achieved from 3.1 to 6.2 GHz (66.7% fractional bandwidth) and an S11 ≤ −10 dB bandwidth is realized from 2.5 to 6.5 GHz (88.9% fractional bandwidth). The proposed antenna is compact with an area of 20 mm2, produces stable radiation patterns, and its simple to design and fabricate without using parasitic elements or introducing slots on the antenna.
A novel miniature wideband microstrip antenna is presented. The proposed miniature design is achieved by exploiting the idea of a quasi-radiator. Here, a part of the radiator is connected to the ground plane through a shorting pin or via. The proposed antenna achieves a starting frequency of 1.8 GHz with a small antenna area of 20 mm 2. An electrical size of 0.05λ is realised leading to a miniaturised design. The proposed antenna is broadband, compact, and produces stable radiation patterns.
Within the frequency band designated by the FCC for UWB systems, there are other frequency bands that are also designated for use for other technologies like and . These systems can cause interference with UWB systems when operated at the same time. Therefore, an antenna operating in the UWB spectrum needs to have band-notch capabilities in order to mitigate interference resulting from nearby communication systems operating within the UWB frequency band. In this paper, the notched bands are achieved by using vertical stubs protruded from a microstrip feedline. The antenna is etched on a 25 Â 30 mm 2 substrate. Two antenna structures are presented; one is designed to notch an intended narrowband from 3.3 -3.6 GHz and the second is designed to include an additional band notch from 5.15 -6 GHz. The simulations and measurements show that the proposed antennas achieve an ultra-wide bandwidth of 3-10.6 GHz with successful single and dual band-notches, good gain and good group delay rejection in the notch bands. Stable radiation patterns with low cross polarization are also realized across the operating bandwidth. A detailed analysis of how the filtering is also achieved using circuit theory is presented in this work as well.
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