DESIGN AND ANALYSIS OF T-STUB U-SLOT NOTCH BAND FREQUENCY RECONFIGURABLE ANTENNA USING PARAMETRIC ANALYSIS FOR WIRELESS COMMUNICATION APPLICATIONS

© 2020 The Author(s). This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. 15 DESIGN AND ANALYSIS OF T-STUB U-SLOT NOTCH BAND FREQUENCY RECONFIGURABLE ANTENNA USING PARAMETRIC ANALYSIS FOR WIRELESS COMMUNICATION APPLICATIONS


INTRODUCTION
Generally, a single antenna provides limited resonant frequencies, single band of operation with limited gain in the present scenario. In order to overcome the single band frequency of operation and limited gain, frequency diversity with multi resonant characteristics from single antenna is essential for the above said applications. In view of this, in the present work, T-Stub U-Slot frequency reconfigurable antenna is designed and its parametric analysis is evaluated. Researchers designed various multiple band antennas to addresses different wireless communication applications such as GPS, GSM, PCS, UMTS, Bluetooth, LTE, Wi-Fi and WLAN etc [1], [2], [3], [4], [5], [6].
Usage of greater number of wireless platforms will have frequency bands and diversity problems. In this paper, three PIN diodes are used to attain frequency reconfigurability. PIN diodes are utilised for high power handling capability, very less driving voltage and low cost. The parametric analysis of T-Stub U-Slot notch band [7] frequency reconfigurable antenna is carried out by varying three important parameters namely, width of the feed (Wf), width of the T-stub (T3) and length of the U-slot (S1) and the results are presented at the end.

ANTENNA DESIGN
The antenna is constructed on FR4 substrate material with permittivity 4.4 and loss tangent 0.02. the dimensions of the antenna are calculated based on the dielectric constant of the substrate material, resonant frequency and impedance with respect to 50 ohms. The design related mathematical formulation is presented in this section with list of parameters. In the patch antenna basic architecture, the physical dimensions of the radiating element are replaced by the dimensions equivalent values obtained. Corresponds to an effective dielectric medium which replaces the existed permittivity of the material. The effective permittivity is different for CPW structures [8], [9], [10] when compared to the microstrip line configuration. It can be expressed as (1) Where W= width of the centre conductor, h = thickness of substrate, G = the gap between the signal conductor and ground and K= W/(W+2G) CPW line has the characteristic impedance which can be expressed in terms of elliptic function of the 1 st kind The ratio of K'(k) and K(k) is expressed by

RESULTS AND ANALYSIS
The parametric analysis of the proposed antenna is accounted with respect to the patch, feed and ground plane. Fig.2 shows that the parametric analysis of the feed width of the antenna Wf is varied from 3.2 to 3.8 mm and the simulated results for the change in Wf are shown in table 2. It is fixed at 3.2 mm since the fundamental resonant frequency is at 3 GHz and second resonating band is from 5 to 8.8 GHz. When the value changed to 3.4 mm , the fundamental resonant frequency is shifted back to 2.9 GHz and second band is from 6 to 8 GHz. This second band is not covering any services. When the value changed to 3.6 mm, the fundamental resonant frequency is at 3.8 GHz and second band from 5.3 to 9.5 GHz. Fig.3 represents the reflection coefficient for change in the width of the T-stub T3 is varied from 2 to 3 mm and the simulated results for the change in T3 are shown in table 3. The optimum dimension is fixed at 2 mm because fundamental resonant frequency is at 3 GHz and second resonating band is from 5 to 8.8 GHz. Fig.4 shows the length of the U-slot antenna S1 is 3 mm, and the simulated results for the change in S1 are shown in table 4. The designed antenna is showing optimum performance since the resonant frequency is at 3 GHz and second resonating band is from 5 to 8.8 GHz.    3.8 5.9 -9.6 3.7 1.6 (4.3 -5.9) Figure 4: Reflection coefficient for change in S1 B. Siva Prasad, and P. Mallikarjuna Rao

CONCLUSION
A compact T-Stub U-Slot frequency reconfigurable antenna with notch band for WLAN, Wi-Fi, LTE and Bluetooth applications is presented in this paper. Parametric analysis is done on the width of the feed (Wf), width of the T-stub (T3) and length of the U-slot (S1) to get the optimised performance characteristics of the designed antenna. From the results, it is clearly showing that, Wf is fixed at 3.2 mm, T3 is showing better results at 3 mm and S1 is giving optimum results at 3 mm. The designed T-Stub U-Slot notch band frequency reconfigurable antenna is operating in the dual band with narrow bandwidth at fundamental resonant frequency and wide bandwidth at second resonant frequency which covers almost all the applications in the Ultra-Wide band range.

SOURCES OF FUNDING
None.