A Self-Diplexing Antenna Designed using SIW Technique for C-Band Applications

The paper explain how the substrate integrated waveguide can often used to implement a self-diplexing antenna for C-Band applications. The designed antenna exploits two quarter-mode SIW cavity resonators. Quartermode SIW cavity resonator is attained from the half-mode SIW cavity resonator by dividing with the assistance of 1 open ended slot. Each quarter-mode SIW cavity resonator is excited separately using microstrip feedlines. The antenna display two resonant frequencies of 6.44 and 7.09 GHz, with the subsequent gain values 4.8 and 6.2 dB respectively. Moreover, the antenna shows unidirectional and stable radiation diagram operating frequencies. The obtained frequencies are ranging between 4-8GHz so the designed antenna can be used for C-Band applications.


INTRODUCTION:
Nowadays wireless communication systems leading a serious role in communication, especially the software defined radios demand a compact, light weight, high performance dual band or multi band antennas [1][2]. SIW technology already experienced a rapid development over quite one decade. This development allows demonstration and applications of innovative passive and active circuits, antennas and systems at microwave and millimeter wave frequencies [3][4][5]. Some multilayered structures are wont to improve the isolation between the input ports [4][5]. In [6] and [7] using non-planar configuration the antennas with self-diplexing capability are implemented. Substrate integrated waveguide is implemented to beat the drawbacks of microstrip and DFW (dielectric filled waveguide). Dual Tstubs loaded apertures are developed in [8] using selfdiplexing antennas. SIW techniques are often utilized in many antenna designs to urge high performance at very high frequencies. SIW technique can be combined with other SIC's platforms to create multiformat and multifunction devices and systems. Using SIW cavitybacked self-diplexing antennas are demonstrated [9-10].

HMSIW and QMSIW:
It occupies large space because of the full wave SIW antenna. A big miniaturization of the SIW antenna is achieved by applying the SIW (HMSIW) and SIW quarter mode (QMSIW) half-wave mode [11][12]. The HMSIW has almost the equivalent distribution of the E-field as the full SIW, although its size is half that. QMSIW is attained by dividing the HMSIW into two parts.

ANALYSIS: 1. Port 1 only excited
When the planning is completed the supported measuring configurations, it's simulated using Ansoft HFSS simulator by exciting only port 1 by microstrip line feeding at a frequency of 6.44GHz and port 2 is terminated employing a terminator, the maximum gain obtained is 4.8dB. The above figure represents that when port 1 only excited the S Parameter value is -19.0270dB at frequency 6.5889GHz. The above figure represents that 3D Gain plot where it ranges from -19.4 to 4.8dB.

Port 2 only excited
When port 2 only excited by microstrip line feeding at a frequency 7.09GHz and terminating the port 1. The utmost gain obtained is 6.2dB. The above figure represents that when port 2 only excited the S Parameter value is -14.3034dB at frequency 7.00GHz.
FIGURE7: 3D Gain plot The above figure represents that 3D Gain plot where it ranges from -19.2 to 6.2dB.
3. BOTH PORT 1 AND PORT 2 ARE EXCITED When port 1 and port 2 are excited at a time with two different operating frequencies i.e. 6.44 and 7.09 GHz. This exhibits the nature of Self-diplexing antenna as it is working at two different frequencies.  The above figure represents that 3D Gain plot where it ranges from -9.2 to 3.6dB.
3. CONCLUSION A self-diplexing antenna using SIW technique for C-Band applications has been successfully designed and simulated using HFSS. Two quarter-mode cavity resonators, placed orthogonally to every other, are used for radiation. The quarter mode resonators are acquired from half-mode SIW resonator by inserting a slanted one open-ended rectangular slot. Each quarter-mode resonator radiates independently, at the corresponding resonance without affecting other. The measured and simulated results show a depth agreement with one another. The obtained resonant frequencies are often used for C-Band applications.