# Circularly Polarized Broadband Printed Antenna for Wireless Applications
## 3 Experimental Result and Discussion  
To validate the feasibility of the proclaimed broadband CP antenna, a constructed prototype was measured and fabricated. The experimental results are measured with an Agilent N5227A PNA microwave network analyzer (Keysight, CA, USA) and a UKM Satimo StarLab (Microwave Vision Group, French). The snapshots of the fabricated antenna are verified in Figure 6a. From the realized results portrayed in Figure 6a, the measured impedance bandwidth of the reflection coefficient below the \(-10\) dB is approximately 7.70 GHz (2.22-9.92 GHz), which is approximately 126.85% with regard to the center frequency at 6.07 GHz. On the other hand, the measured 3 dB AR bandwidth is around 2.64 GHz (2.28-4.92 GHz), which is approximately 73.33% at 3.60 GHz in Figure 6b. The measured and simulated radiation patterns at 2.40 GHz, 3.50 GHz and 4.30 GHz are plotted in Figure 7. The antenna radiates a bidirectional wave with opposite sense circular polarization. The radiation pattern of the  
Figure 5: Numerical S\({}_{11}\) and AR performance with different values of (**a**) \(R1\), (**b**) \(R2\), (**c**) \(R3\), (**d**) \(L1\), (**e**) \(\alpha\).  
antenna is usually LHCP (Left Hand Circular Polarization) for Z \(>\) 0 and RHCP ((Right Hand Circular Polarization) for Z \(<\) 0. It can be seen that the primary beam direction hardly shifts away from the zenith at both frequencies. The measured and simulated broad sight gains and antenna efficiency are shown in Figure 8. The average measured peak realized gain is greater than 3.98 dBic in the realized CP operating band and the maximum peak realized gain is around 4.85 dBic at 4.92 GHz. The antenna efficiency of the archived 3 dB AR frequency band range is approximately 80%.  
Figure 6: The numerical and measured results of (**a**) S\({}_{11}\) (Reflection coefficient) and (**b**) ARBW.  
Figure 7: The numerical and measured CP radiation patterns at (**a**) 2.4 GHz (LHCP and RHCP) (**b**) 3.5 GHz (LHCP and RHCP) and (**c**) 4.3 GHz (LHCP and RHCP).  
Table 1 describes the overall performance of the realized antenna with existing literature reviewed antennas in the literature review section. Here \(\mathbf{\lambda_{0}}\) refers to the wavelength of the lowest frequency band for each reported antenna. It can be clearly noticed that the realized antenna achieves the widest fractional bandwidth in terms of dimension, impedance, and AR bandwidth property. Table 2 reveals the impedance and axial ratio bandwidth performance with applications of the recommended design for the various scaling dimension (L) just., It could be observed from the presented table that the wide impedance (a lot more than 75%) and AR bandwidth (more than 66%) have already been accomplished for the scaling dimension (L) without varying the additional antenna parameters. If the realized parameters, such as \(R1\), \(R2\), \(R3\), \(L1\), and \(\alpha\), could be tuned, the impedance and AR bandwidth may also be improved. Therefore, any researcher could be very easily remodeled from the recommended created for any preferred wide CP working band application through the scaling dimension (L) without varying the form, which may increase the sensor journal reader interest of the offered antenna.  
Figure 8: The numerical and measured (**a**) peak realized gain and (**b**) efficiency.