Miniaturised low‐profile super‐wideband Koch snowflake fractal monopole slot antenna with improved BW and stabilised radiation pattern

Abstract

This communication explores the super‐wideband Koch snowflake fractal monopole slot antenna for different wireless/multiband applications. The antenna comprises of a modified star‐shaped patch, a 50 Ω triangular tapered feedline, a partial slot loaded ground plane and an I‐shaped parasitic element located beneath the radiating element. The self‐similarity and space‐filling features of Koch iteration technique have been employed at the triangular patch to acquire the antenna compactness and broadband performances. Further by placing a pair of symmetrical L‐shaped slots and an inverted U‐shaped slot in the ground plane, a super‐wide‐impedance bandwidth (BW) (|S11|<−10thinmathspacedB) of 650 MHz–20 GHz with a ratio BW of 30.7:7 is attained. The proposed antenna has a compact size of 17 × 29 × 0.787 mm3 and has a stable radiation pattern over the entire frequency spectrum. For pattern stability, an I‐shaped parasitic element was utilised. Moreover, the typical antenna parameters such as return loss, gain, radiation pattern and group delay have been simulated and verified experimentally. Time‐domain characteristics have also been studied.

Fractal antennas and arrays: a review and recent developments

“…It has a capability to radiate at Bluetooth frequency band with additional band notch characteristics at WLAN frequency. In [168], a super-wideband Koch snowflake fractal monopole slot antenna for different wireless/multiband applications is presented. It comprises of a modified star-shaped patch where self-similarity and space-filling features of Koch iteration technique have been employed to achieve the antenna compactness and broadband performances.…”

Ultra-Wideband Trident Inset-Fed Monopole Antenna With a 3-D Conical Ground

“…UWB monopole antennas can be categorized into two prominent designs: the first is monopole with the vertically standing radiator mounted perpendicularly to a metal plate [2][3][4][5][6][7]. The second design has the radiator in-plane with the ground and is mostly implemented with a PCB [8][9][10][11]. The latter have in recent years been integrated into mobile devices thanks to printed circuit board (PCB) miniaturization techniques with various radiator and ground geometries.…”

“…The latter have in recent years been integrated into mobile devices thanks to printed circuit board (PCB) miniaturization techniques with various radiator and ground geometries. Such antennas can attain up to 30:1 impedance bandwidth ratio [8].…”

“…This was achieved at the expense of negative antenna gains at lower frequencies (< 1 GHz) and poor cross-polarization at higher frequencies. The Koch snowflake fractal monopole design by [8] aimed to stabilize the radiation patterns over a 30:1 operating bandwidth ratio from 0.65 to 20 GHz by employing parasitic elements in the ground structure. The antenna nonetheless suffered from zero decibel gain performance at the lower frequencies and distorted patterns in the middle and upper frequencies.…”

Wideband printed slot antenna using Koch fractal metasurface structure

“…B. Mandelbrot to describe a family of complex shapes, some of them having an inherent self‐similarity in their geometrical structure. Koch curve, a typical fractal metasurface structure, has been used to develop wideband, multiband or miniaturized antennas . Here, the boundary of the printed slot antenna in this letter was etched by Koch metasurface structure to enhance the impedance bandwidth.…”