# 3D-printed super-Wideband Spidron Fractal Cube Antenna with Laminated Copper
## 1 Introduction  
From the late 1950s to the early 1960s, antennas with a reflection ratio bandwidth of 10:1 or greater (e.g., log-periodic dipole and equiangular spiral types) started to be developed [1]. At that time, these antennas were known as frequency-independent antennas, but they are currently referred to as super-wideband (SWB) antennas. SWB antennas have received much attention in military and civilian systems because their broadband characteristics can provide high data-rate services [2]. For this reason, several 2D and 3D SWB antennas have been introduced [3; 4; 5; 6; 7]. The modified star-triangular fractal monopole antenna introduced by [PERSON] et al. [3] and the asymmetric coplanar strip fed hexagonal loop antenna from [PERSON] et al. [4] have 2D geometries and compact sizes, meeting the \(-10\) dB reflection ratio bandwidth requirement of 30:1 or greater. However, their performances can deteriorate with changes in the ground size or platform. In other work [5; 6; 7], 3D SWB antennas with a monopolar patch and dielectric resonator were proposed. It was found that these antennas are insensitive to the ground platform used; however, the fabrication of the 3D structure of these antennas remains a challenge. Moreover, their weight is increased due to the use of a dielectric resonator.  
A self-complementary structure in which the geometries of the conductor and non-conductor parts are nearly identical was proposed by [PERSON] in 1948 to realize frequency-independent properties [8]. Owing to this feature, wide bandwidth characteristics are easily achieved. Accordingly, various wideband self-complementary antennas have been published [9; 10]. [PERSON] suggested a bow-tie-shaped quasi-self-complementary antenna [9]. In another study [10], an arrow-shaped self-complementary antenna for WLAN/WiMAX applications was proposed. These antennas are small and have wide bandwidths but do not have SWB characteristics. On the other hand, antennas that demonstrate SWB characteristics using a self-complementary structure have also been proposed [11; 12]. [PERSON] proposed a non-planar log-periodic antenna with a quasi-self-complementarystructure and analyzed the performance and characteristics of the antenna in detail [11]. However, the antenna was still heavy due to the thick metal used to make it. In another study [12], a spherical self-complementary antenna was introduced. This antenna was designed with a teardrop-shaped loop to maintain a self-complementary structure and was fabricated using a 3D printer. Although the antenna is light due to the 3D printing procedure, its measured result does not meet the 10:1 reflection ratio bandwidth requirement.  
Previously, we introduced two-dimensional Spidron fractal configurations for various antenna applications--specifically, a Spidron fractal slot antenna with a grooved dielectric resonator [13] and a uniplanar electromagnetic bandgap employing a modified Spidron fractal geometry [14]. In the present paper, a novel 3D-printed SWB cube antenna with a Spidron fractal configuration is proposed. Each parameter of the Spidron fractal geometry is set to satisfy the requirement of the self-complementary condition, and the antenna is fed by a tapered microstrip balun [15]. As a result, the proposed antenna achieves SWB characteristics. ANSYS high-frequency structure simulator (HFSS) software is used to conduct all simulations in this paper. In addition, 3D printing technology is applied for the simple fabrication of a prototype of the antenna. The proposed antenna with its tapered balun is measured to verify simulated results. The designs of the antenna and the balun are introduced in Section 2. Section 3 presents a comparison between the measured and simulated results. Finally, the conclusion is given in Section 4.