Figure 3, shows the correlation plots of the simulated return loss curves against frequency for various patch configurations. Return loss specifies the amount of power reflected back. The above figure ensures the course of action of the reduced patch with the partial ground which enhances the antenna to envelop an X and Ku-band range. To upgrade radiation efficiency by reducing the return loss of the antenna, F shapes and rectangular slots are inserted in the patch which covers X band (8–12 GHz) for radar applications and ku band (12–18 GHz) for satellite applications. Designed microstrip patch antenna characteristics are shown as follows
3.1 Return Loss of prosed Antenna
When simulated return loss is plotted on Y-axis with respect to the frequency on X-axis, Fig 4 shows that the suggested antenna reveals X and Ku-band behaviors. We minimize the return loss, by interposing double F- shape, the two rectangular slots both left and right sides in the bottom of the patch and corner cuttings, which makes it to resonate six multiple bands 8.6181 GHz, 12.3116 GHz, 14.196 GHz, 15.6281 GHz, 18.1910 GHz, and 18.9447 GHz with the return loss of -23.8351, -32.9380, -14.6726, -22.2810, -19.0592, and -18.8137 respectively. Thus, the HFSS simulation result confirms that the return loss for the aimed multiband has been attained.
3.2 VSWR of designed antenna
VSWR is an essential requirement for the proper function of the antenna which implies the impedance matching between the source and the feed is optimum. It depicts the pattern and behavior of the antenna. In figure 5, the VSWR investigation has been shown. The VSWR obtained at the favored multiband is 1.11 at frequency 8.61 GHz, 0.39 at frequency12.31 GHz, and 1.33 at frequency15.62 GHz, 1.94 at frequency 18.19 GHz respectively. Thus, the proposed antenna is capable of providing the coveted VSWR outcomes.
3.3 Gain of the proposed Antenna
The power radiation in a given direction is revealed by the antenna gain. Figure 6(a), 6(b), 6(c), 6(d), 6(e), 6(f) shows the 3D view of the broadband gain of the designed antenna which varies with respect to the frequency. The achieved gains are 2.9757 dB, 3.8395 dB, 3.0622 dB, 5.3433 dB, 6.0244 dB, 6.3769 dB at the resonated multiband frequency is 8.6181 GHz, 12.3116 GHz, 14.1960 GHz, 15.6281 GHz, 18.1910 GHz, and 18.9447 GHz respectively. The highest attainable gain for the suggested antenna is 6.3769 dB at a frequency of 18.9447 GHz which means the antenna is more efficacious at this frequency, while a low gain of 2.9757 dB at a resonant frequency of 8.6181 GHz which means the antenna is lesser effective at this frequency. The designed antenna exhibits the peak gain of 6.3769 dB is obtained at 18.9447 GHz frequency which makes the antenna advantageous for Satellite communication applications.
3.4 Directivity of the proposed Antenna
Fig (7) shows the directivity of the suggested microstrip patch antenna versus frequency. The potential of an antenna that improves energy in a specific direction when transmitting energy better from a particular direction when receiving such as reveling by directivity. It exhibits 3.3307 dB, 4.8116 dB, 3.6372 dB, 6.5220 dB, 6.3752 dB, and 6.9104 dB at the resonated multiband frequency of 8.6181 GHz, 12.3116 GHz, 14.1960 GHz, 15.6281 GHz, 18.1910 GHz, and 18.9447 GHz respectively. We come to know from the directivity plot that the maximum amount of radiation intensity which is equivalent to 6.9104 dB is attained at a resonant frequency of 18.9447 GHz. Table (4) which is given below reveals the Return loss, VSWR Gain, Directivity, and radiation efficiency for different resonant frequencies of the proposed antenna
Table (4) presents the characteristics of the proposed microstrip patch antenna.
Resonance frequency(GHz)
|
Return Loss(dB)
|
VSWR
|
Gain(dB)
|
Directivity(dB)
|
Radiation efficiency (%)
|
8.6181
|
-23.8361
|
1.1186
|
2.9757
|
3.3307
|
89
|
12.31116
|
-32.9380
|
0.3918
|
3.8395
|
4.8116
|
79
|
14.1960
|
-14.6726
|
|
3.0622
|
3.6372
|
84
|
15.6281
|
-22.2810
|
1.3386
|
5.3433
|
6.5220
|
81
|
18.1910
|
-19.0592
|
1.9440
|
6.0244
|
6.3752
|
94
|
18.9447
|
-18.8137
|
|
6.3769
|
6.9104
|
92
|
3.5 Radiation Pattern
The 3D radiation patterns for the elevation and azimuthal plane respectively of the proposed antenna is illustrated in figures above. The radiation pattern indicates the graphical portrayal of the radiation properties of the antenna as a function of space. The radiation pattern reports how an antenna causes energy radiation into space and reception.
Table. (5) Comparison of performance of the antenna introduced in previous literature’s with the existing work
Published Antenna
|
Antenna size
(mm)
|
Height (mm)
|
Ground
(mm)
|
Return Loss
(dB)
|
Maximum Gain
(dB)
|
Resonant Freq [GHz]
|
Radiation
Efficiency%
|
Applications
|
Ref.[5]
|
24x36
|
1.6
|
24x20
|
-21.7911
-33.6083
-23.0760
|
3.01
|
4.92
4.99
5.02
|
-
|
UWB band
|
Ref.[6]
|
30x30
|
1.6
|
30x30
|
-26.85
-16.13
|
6.27
|
9
10.35
|
-
|
X band
|
Ref.[7]
|
30x30
|
1.6
|
30x30
|
-15.92
-14.84
|
7.5
|
9
10.14
|
-
|
X band
|
Ref.[8]
|
20x20
|
1.6
|
20x20
|
-23
-14
-13
|
5.13
|
11.3
12.6
12
|
89.2
|
X and Ku bands
|
Ref.[9]
|
38x35
|
1.57
|
34x34
|
-38
-19
-16
-12
|
6.4
|
5.5,
8.5
12.5
20
|
93
|
X and ku bands
|
Proposed Antenna
|
40x26
|
1.43
|
16.2x12.12
|
-23.83
-32.93
-14.67
-22.28
-19.05
-18.81
|
6.37
|
8.61
12.31
14.19
15.62
18.19
18.94
|
94
|
X and ku bands
|
From the above table (5), we come to know that the proposed antenna has similar characteristics which are as per with the already suggested antenna’s. Based on the popular microstrip antenna parameters such as size, resonant frequencies, return loss, and radiation efficiency, a fair comparative analysis is presented with the other considered antennas. The antenna performance lies in the X and ku frequency band.
The main focus of our designed antenna is to achieve “Size reduced”, “multiband resonant frequencies” and hence can be taken up for multi commercial purposes. This antenna has been profitably executed after numerous modeling and simulations by Ansoft HFSS 13.0 software to get the best solution of the parameters for overall performance. After getting good results from the simulated and measured parameters, the target was achieved.