## 1 Introduction  
Monopole antennas are favored in wireless communication applications due to their wide bandwidth, small size, design simplicity, and ease of integration with the other devices [1]. Such wideband antennas are very useful for lung cancer and microwave imaging [2, 3]. In 1976, [PERSON] and [PERSON] introduced a wideband application monopole antenna [4]. Among other types of antennas, monopole antennas well known because of their suitable applications, i.e., Bluetooth, wireless USB dongle, satellite communication, HIPERLAN/2, and WIMAX [5]. Researchers have designed and implemented different types of monopole antenna structures to achieve wide bandwidth, e.g., U-shape monopole [6], octagon shape [7], printed T-shape [8], spline-shaped monopole [9], Koch fractional shape [10], FTSE (folded t-shaped monopole) [11], and trident shape strip-feed monopole [12]. Moreover, researchers have used various techniques to achieve super wide bandwidth, such as defected ground structures where different types of slots were used in the ground plane of the antenna. Such designs consist of tapered shape slots [13], hexagonal slots [14], and T-shape slots [15]. In microstrip antennas, DGS is used for the enhancement of gain and bandwidth. Also, it has been used for higher mode harmonic suppression, mutual coupling between elements, and to improve the characteristics of the microstrip antenna radiation. The second method is to change the feeding line; it uses a suitable feeding line for proper impedance matching over a broad range of frequencies to achieve wide bandwidth. Some examples of this are the antipodal Y-strip [16], dual orthogonal microstrip feeding lines [17], and an inverted F-feed line [18]. The third technique is the use of meander line structures that are suitable for wide bandwidths due to their mutual coupling mechanism. This type of structure is used to miniaturize antennas. Its different parts operate at different frequencies [19]. Nowadays, the demand for super-wide band antennas for both long- and short-range transmissions for future ultra-wide band communication applications is very high. The term SWB (super-wideband) refers to bandwidth ratios of 10:1 or higher at a 10 dB return loss [20]. Many SWB antennas for advanced wireless communication in civilian and military systems are presented in the literature. Recently, several monopole antennas have been designed which achieve wide bandwidths. One recent research work presented a monopole antenna having a wide bandwidth. The antenna achieved 86% radiation efficiency and 153.22% fractional bandwidth, and its applications included WLAN, WiMAX, ISM, and wireless communication [21]. In [22], a monopole antenna was implemented for WPAN (wireless personal area network) with a 79.21% radiation efficiency and a 135.2% fractional bandwidth. In [23], slotted antennas were designed with a microstrip feeding line, and the author achieved 138% bandwidth and 88% radiation efficiency. In [24], a circular antenna using a waveguide transformer feeding line was presented. It achieved a super wide bandwidth of 165.7% (2.7-28.8 GHz). In [25], a super wide band antenna is presented; it achieved a 133% (10-50 GHz) bandwidth by using an octagonal fractal microstrip patch. A propeller shape was used by replacing the circular radiating shape of the monopole antenna to achieve a 168% (3-35 GHz), operating bandwidth [26]. These examples show that with the help of monopole antennas, super-wide bandwidths can easily be achieved by using multiple techniques. This paper describes an S-shape stepped meander line monopole antenna with a defected ground structure which is capable of operating at a super-wide bandwidth. The simulated operating frequency of the antenna is from 3.08 GHz to above 40.9 GHz, and the measured frequency range is from 3.09 GHz to 40.2 GHz. A quarter waveguide transformer feeding line is used for best matching and to achieve a wide bandwidth. Two antennas were tested with side by side and face to face alignments to check the performance in the time domain.