The paper presents microstrip patch antennas, which are based on the fractal antenna concept, and use planar periodic geometries, providing improved characteristics. The properties of the fractal structure were used in a single-fractal layer design as well as in a design, which employs fractals on both the upper and bottom layers of the antenna. The final structure, i.e., a double-fractal layer antenna has been optimized to enhance bandwidth and gain of the microstrip antenna. The proposed geometry significantly improved antenna performance. The antenna could support an ultra-wide bandwidth ranging from 4.1 to 19.4 GHz, demonstrating higher gain with an average value of 6 dBi over the frequency range, and a radiation capability directed in the horizontal plane of the antenna.

This paper proposes a microstrip patch antenna based on the left-handed metamaterial concept, using planar periodic geometry, which results in improved characteristics. This periodic geometry is derived from fractal shapes, which have been widely used in antenna engineering. The metamaterial property was obtained as a result of the double-fractal structure on both the upper and the bottom sides of the antenna. The final structure has been optimized to enhance bandwidth, gain, and radiation characteristics of the microstrip antenna. This combination significantly improved antenna performance; our design could support an ultrawide bandwidth ranging from 4.1 to 19.4 GHz, demonstrating higher gain with an average value of 6 dBi over the frequency range and a peak of 10.9 dBi and a radiation capability directed in the horizontal plane of the antenna.

Although fractal structures have the property of self similarity and ease of repetitiveness, they remain less used in planar patterned metamaterial structures. In this context a compact Ultra Wide Band (UWB) microstrip antenna based on planar metamaterial concept is proposed. The planar metamaterial is designed by etching an array basing on Sierpinski gaskets fractal pattern and isosceles triangles respectively on the patch and the ground plane. The substrate of the designed antenna is Rogers RT 5880 with εr=2.2 and 0.787 mm height. The measured impedance bandwidth ranges from 4.439 GHz to 15.785 GHz, for a less than q̑10 dB return loss, it is 11.346 GHz bandwidth, which represents 112%. The antenna has a radiation pattern mainly directed in the horizontal plane.

Many telecommunication applications require antennas capable of operating in a wide (or even ultrawide) frequency band. While LPDA (log-periodic dipole array) antennas are very practical in real-world applications, their usefulness is impeded due to frequency limitations caused by their truncated structures. To increase the upper-frequency range of the LPDA antenna, an additional parameter—the ratio factor—was introduced during the antenna geometry design process. This parameter allows us to improve the properties of an antenna with truncated geometry. In this paper, the proposed technique was used to design, manufacture and present an antenna capable of operating in a frequency range between 760 MHz to 18 GHz. The electrical properties of the proposed antenna were compared with a reference antenna. The designed antenna was experimentally validated, and the simulated results were verified as well.