## 1 Introduction  
Recently, wireless communication systems of a small and compact size that operate in a wide-band operation need compact and wide-band antennas that can be easily integrated with them [1; 2]. CP antennas have several benefits, such as better mobility, orientation flexibility between the transmitting and receiving ends, decreasing multipath interference, and polarization mismatch [3; 4; 5]. Two orthogonal modes with equal magnitudes and a 90\({}^{\circ}\) phase shift must be generated to produce the CP operation [1]. In modern wireless systems, for example, wide-band circular polarization (CP) antennas, radio frequency identification (RFID), and global positioning systems (GPSs) are recommended and utilized. Recently, wireless systems have been operated at different frequency bands. Therefore, wide-band CP antennas are considered a good choice to reduce the system's complexity and price [6; 7; 8]. Microstrip [9; 10; 11; 12], dielectric resonator (DRAs) [7; 8], slot [13; 14], and monopole antennas [2; 3; 4; 5; 15; 16; 17; 18; 19; 20; 21; 22; 23; 24] are used to achieve CP behavior. Microstrip antennas have several advantages, such as low price, simple design, small size, ease of integration, and simplicity in CP realization. Therefore, the microstrip antenna is used in several communication systems. However, conventional CP antennas are produced with a small 3 dB axial ratio with a large size, which cannot be suitable for wide-band systems [9; 10]. For this reason, monopole antennas can be used to produce a wide-band CP operation. The monopole antennas can be fabricated easily and have a small size, low price, stable radiation patterns, wideband bandwidth, and CP operation. Therefore, recently, researchers have extensively studied them [2; 4; 5]. To enhance the 3 dB AR bandwidth and preserve the antenna compactness, a monopole antenna can be utilized [2; 3; 4; 5; 15; 16; 17; 18; 19; 20; 21; 22; 23; 24]. In [2], a parasitic G-shaped strip is added to a C-shaped monopole antenna to generate a CP operation. The antenna is operated from 3.92 to 7.52 GHz (62.9%). The FR4 substrate at 1.6 mm is utilized in the design. The antenna had a size of 30 \(\times\) 32 mm\({}^{2}\) and peak gain of 3.6 dB. Additionally, the ground plane is modified to increase the 3 dB AR bandwidth to 53.92% from 4.28 to 7.44 GHz. The antenna has a simple structure with a wide-band 3 dB AR bandwidth and is utilized for WLAN communication. The UWB CP operation generated using a sequential phase feed is investigated in [3]. It is composed of a monopole antenna with a circular arc-shaped radiator on the top of the RO4003 substrate with a 0.813 mm thickness and a quasi-elliptical strip connected to the partial ground on the other side. The antenna is operated from 1.8 to 7.3 GHz (120.9%). The antenna has a size of 120 \(\times\) 120 mm\({}^{2}\) and a peak gain of 11.2 dB. Additionally, the antenna has a 3 dB AR bandwidth from 1.5 to 7.5 GHz (133.33%). While the AR in [3] has a UWB operation, the antenna has a larger size and complex design. In [4], a broadband antenna with a C-shaped monopole patch on the top side and an open-loop rectangular resonator and modified ground on the back side is investigated to extend the 3 dB AR to 65.2% from 4.28 to 8.42 GHz. A compact broadband antenna with a circular C-shaped patch, an improved ground plane, and a large size to extend the 3 dB AR are investigated in [5]. The antenna is operated from 2.25 to 7.35 GHz (106.3%). The FR4 substrate of 1.6 mm is utilized in the design. The antenna has a size of 49 \(\times\) 55 mm\({}^{2}\) and a peak gain of 6.55 dB. Additionally, the ground plane is modified to increase the 3 dB AR bandwidth to 104.7% from 2.05 to 6.55 GHz. The antenna has a simple structure with a wide-band 3 dB AR bandwidth and is utilized for WLAN communication; however, it has a large size. A microstrip antenna utilizing a fractal-defected ground structure is discussed in [9]. The antenna is worked from 1.55 to 1.58 GHz (1.9%).