Reduction in Return Loss of a Novel Reconfigurable Antenna at 3.4 GHz by FR4 Substrate Using Double PIN Diodes

Aim: The main objective of the project is to reduce the return loss of a reconfigurable antenna at 3.4 GHz by using FR4 substrate with Double PIN diodes. Materials and Methods: Two diode configurations of single PIN diode and Four diodes configuration of double PIN diodes are used with a sample size of 6. Results: From HFSS simulation software Return Loss(-30.2dB) and VSWR (1.10) of Reconfigurable Monopole antenna is improved by FR4 substrate using Double PIN diodes. Attained significance ratio(P=0.05) in statistical analysis. Conclusion: Double PIN diode of a reconfigurable Monopole antenna performs well (Return Loss is reduced by -7dB) when compared with a single PIN diode of a reconfigurable Monopole antenna. Key-words: Monopole Antenna, PIN Diode, WLAN, WIFI, Return Loss, VSWR, FR4 Substrate, Novel Reconfigurable Monopole Antenna, Antenna Design.


Introduction
The research is about reducing the return loss of reconfigurable monopole antennas using a double PIN diode . The importance of this project is the need for low return loss antennas for satellite communication (Kumar, Kishan Kumar, and Prasanth 2015). The reconfigurable antennas are used in current portable devices WLAN and WIFI applications (Dwivedy, Behera, and Mishra 2015), (Zarin et al. 2019).
Double PIN diodes comparing with a Reconfigurable antenna using Single PIN diode, Sample size was calculated by using previous study Results (Shoukat et al. 2016) using clincalc.com by keeping alpha error-threshold by 0.05, 95% confidence interval, Power 80%. In this study we compare the Parameters like Return Loss, VSWR by taking 6 samples, one sample group by using previous literature (Shoukat et al. 2016 Effective length of patch is calculated as: Length of extension ∆L is the additional length due to the fringing fields and it is calculated as: Actual length of patch is calculated using: Proposed antenna Width and Length of patch calculated from the above equations are: Patch Width ( 1 = 2.5 , 2 = 4 , 3 = 8.5 , 4 = 2 ) = 21.8 Patch Length ( 1 = 12.8 , 2 = 10.1 , 3 = 8.5 , 4 = 18.6 ) = 50 The antenna is simulated by using the above design equations in HFSS Software.

Design of Reconfigurable Monopole Antenna Using Single PIN Diode
Single PIN diode is inserted at one of the slots in a patch of a Reconfigurable Monopole antenna design (Fig.2) where we need to change the resistance values(0.1uohms,1000Gohms) for ON and OFF conditions of a PIN diode switch. The 8th Generation Intel core processor(up to 8MB cache) was used in the testing setup configuration to design the antenna in the HFSS software. The antenna is designed at a frequency of (3.4GHz) and is used as the testing input. The antenna can be constructed by defining the variables(L,W,H,F) and assigning the boundaries and lumped ports of the antenna using HFSS software. The frequency sweep is applied to the configuration to validate and to obtain the results.  The minimum Return Loss and VSWR obtained is represented in Fig.3 & Fig.4 . It shows the variations of Return Loss and VSWR for ON and OFF conditions. The amount of loss of power is minimum when the diode is ON and the power loss is maximum when the diode is OFF. VSWR is minimum when the diode is ON and Maximum when the diode is OFF. (c) Return loss Vs Frequency, when DIODE is OFF. (d) VSWR Vs Frequency, when DIODE is OFF. Fig. 3(a), It was observed that the Return Loss Vs Frequency at 3.4GHz is plotted and the minimum return loss for Reconfigurable monopole antenna using Single PIN diode is -23.8dB, when the Diode is ON.

Data Collected by Making the ON and OFF Conditions of PIN Diodes
From Fig. 3(b), The VSWR against Frequency graph is plotted using Single PIN diode and the minimum VSWR at 3.4 GHz is 1.09, When the Diode is ON.
From Fig. 3(c) Fig.4(a), it was observed that the Return Loss Vs Frequency graph is plotted using a Double PIN diode and the minimum Return Loss at 3.4GHz is -30.2dB, when both the Diodes are ON.
From Fig.4(b), The VSWR against Frequency graph is plotted using Double PIN diodes and the minimum VSWR at 3.4 GHz is 1.10, When both the Diodes are ON.
From Fig.[4(c),4(e)], it was observed that the Return Loss Vs Frequency graph is plotted using a Double PIN diode and the minimum Return Loss at 3.4GHz is -17.8dB, when the Diodes are D1=ON, D2=OFF (or) D1=OFF, D2=ON.
From Fig.4(g), it was observed that the Return Loss Vs Frequency graph is plotted using a Double PIN diode and the minimum Return Loss at 3.4GHz is -18.5dB, when both the Diodes are OFF.
From Fig.4(f) Ramadurai et al. 2019). We hope this study adds to this rich legacy.
The double PIN diode configuration to reduce the return loss of a reconfigurable monopole antenna is used to support only dual band operation.
Usage of reconfigurable monopole Antenna with reduction in Return Loss for quad band and penta band applications.

Conclusion
Reconfigurable Monopole antennas using Double PIN diodes appear to be better (Return Loss is reduced by -7dB) when compared with a single PIN diode. It operates in a dual band mode (WLAN, WIFI) when all the switches are in ON condition, and Single band when it is in OFF condition.

Declarations
Conflict of interests: No conflict of interest in this manuscript.