Research Article
a
May
2018
Computer Science and Software Engineering
ISSN: 2277-128X (Volume-8, Issue-5)
Design and Comparative Analysis of Rectangular Slot
Microstrip Patch Antennas for X-band Applications
Pushpinder Singh, Er. Gaurav Monga
Dept. of Electronics and Communication Engineering J.C.D.M. College of Engineering, Haryana, India
[email protected], [email protected]
Abstract: Microstrip patch antenna is a compact antenna which suffers the limitations of poor gain and reduction in radiation pattern. To reduce the resonance frequency of microstrip antenna increases the length of surface current with help of cutting slots in the patch. In this paper, a comparison of four Microstrip antennas with unequal length of rectangular slots is proposed. The microstrip antennas having rectangular shaped ground plane and FR4-epoxy substrate with relative permittivity 4.4, relative permeability 1 and dielectric loss tangent 0.02 with an overall size of 100×100×5 mm3. The performance of antennas is compared with slots in the patch and the effects of rectangular slots using operating frequency of 8 to 12 GHz are presented. The design simulate and analyze on FEM based HFSSv11 and this helps to compute VSWR, return loss, gain, radiation efficiency and 3D polar plot of the proposed microstrip antenna. The proposed configuration gives broadside gain of more than 8 dBi and VSWR (>2) over entire range in simulated results.
Keywords: Microstrip patch antenna, Rectangular slot, return loss, VSWR, 3D polar plot, gain.
I. INTRODUCTION
Microstrip antenna is consists of a dielectric substrate which is sandwiched in between a ground plane and a metallic patch. Microstrip patch antennas are widely used because of their several benefits like light weight, low volume, low fabrication price, and capability of several frequency operations. But microstrip antennas suffer from a several disadvantages significantly the low power handling capability, narrow bandwidth and low gain. This is a limitation of these microstrip patch antennas. There are number of techniques used to overcome this narrow bandwidth limitation. These techniques increase the thickness of the dielectric substrate and decrease dielectric constant. These techniques have drawbacks like, excitation of surface waves and increase in antenna size.
II. ANTENNA DESIGN
The antennas are designed for 8 to 12 GHz with the structure, as shown three dimensional view in fig.1 and top view in fig.2. The patch of microstrip antennas feed by using microstrip line and both are connected with transmission line. This feed line lies vertically between patch and ground plane which are separated by FR4-epoxy dielectric substrate. The microstrip feed line is of width 5 mm and printed in the middle, along the x axis. The characteristic impedance of feed line and transmission line is 50 ohms.
Fig.1: Three dimensional view of four microstrip patch antennas.
Fig.2: Top view of four microstrip patch antennas.
MSA(a) MSA(b) MSA(c) MSA(d)
ISSN(E): 2277-128X, ISSN(P): 2277-6451, pp. 48-54
III. DESIGN PROCEDURE
In these microstrip antennas, transmission line connects to inner patch and two L shape patch strips. These patch strips have dimensions 75×40 mm and these strips are 10 mm and 5 mm wide respectively. The gap between inner patch and patch strips is 10 mm. The size of inner patch of MSA(a) is 50×50 mm and other ones like MSA(b), MSA(c) and MSA(d) have same size of inner patch that is 55×55 mm. These inner patches have slots of unequal size and shape.
IV. SIMULATION RESULTS
The results of proposed Rectangular Slot Microstrip antenna are Simulated on FEM based HFSSv11. The figures shown below represent various results like; Return loss, VSWR, 3D Polar plot, Radiation pattern during simulation and comparison of these parameters shown in Table no.1.
(1) Return loss
Fig.3 Return loss of MSA(a)
The above figure represents the value of return loss for MSA(a) is -29.452 at frequency 10.111GHz.
Fig.4 Return loss of MSA(b)
The above figure represents the value of return loss for MSA(b) is -30.636 at frequency 10.2778GHz.
ISSN(E): 2277-128X, ISSN(P): 2277-6451, pp. 48-54
The above figure represents the value of return loss for MSA(c) is -31.372 at frequency 10.2778GHz.
Fig.6 Return loss of MSA(d)
The above figure represents the value of return loss for MSA(d) is -43.860 at frequency 10.667GHz.
(2) VSWR
Fig.7 VSWR of MSA(a)
The above figure represents the value of VSWR for MSA(a) is 1.0697 at frequency 10.111GHz.
Fig.8 VSWR of MSA(b)
The above figure represents the value of VSWR for MSA(b) is 1.0606 at frequency 10.2778GHz.
ISSN(E): 2277-128X, ISSN(P): 2277-6451, pp. 48-54
The above figure represents the value of VSWR for MSA(c) is 1.0555 at frequency 10.2778GHz.
Fig.10 VSWR of MSA(d)
The above figure represents the value of VSWR for MSA(d) is 0.1114 at frequency 10.2778GHz.
(3) Radiation pattern
Fig.11 Radiation pattern of MSA(a)
ISSN(E): 2277-128X, ISSN(P): 2277-6451, pp. 48-54
Fig.13 Radiation pattern of MSA(c)
Fig.14 Radiation pattern of MSA(d)
The above figures represent the value of radiation pattern, which shows MSA(a) is better than others.
(4) Gain
Fig.15: 3D Polar plot of MSA(a)
ISSN(E): 2277-128X, ISSN(P): 2277-6451, pp. 48-54
Fig.16: 3D Polar plot of MSA(b)
The above figure represents the value of Gain for MSA(b) is 1.5417 at frequency 10.2778GHz.
Fig.17: 3D Polar plot of MSA(c)
The above figure represents the value of Gain for MSA(c) is 2.1206 at frequency 10.2778GHz.
Fig.18: 3D Polar plot of MSA(d)
ISSN(E): 2277-128X, ISSN(P): 2277-6451, pp. 48-54
Table no.1: Comparison table
MSA(a) MSA(b) MSA(c) MSA(d)
Return Loss -29.452 -30.372 -31.372 -43.860
VSWR 1.0697 1.0606 1.0555 0.1114
Gain 3.0313 1.5417 2.1206 8.6621
Frequency 10.111 10.2778 10.2778 10.1667
In comparison table we can see that values of parameter of MSA(d) are more appropriate than others.
V. CONCLUSION
In this paper, the parameters of four microstrip antennas having slots of unequal size and shape are compared.
Thicker substrate of size 100×100×5 mm3 resolved the problem of narrow bandwidth. The simulated results present for
different microstrip antennas on FEM based HFSSv11, indicates that MSA(d) has better results as compared to MSA(a), MSA(b) and MSA(c). MSA(d) has return loss value -43.8607dB at 10.166GHz, VSWR value is 0.1114 and gain is 8.6621dB. These designed microstrip antennas are used for wireless communication, satellite, Radar at X-Band.
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