This work deals with the design and simulation of patch antenna that provides resonance at frequency 9.968 GHz and applicable for RFID, WiMAX, and X-band applications. The antenna has a -10 dB impedance bandwidth of 300 MHz ranging from 9.8 GHz to 10.1 GHz. The prospect of this design is to obtain a small size, light weight and low-cost miniaturized antenna with good antenna characteristics and ease of integration using feed-networks. The basic theory and design are analyzed, and the simulation results are obtained using computer simulation technology (CST) Microwave Studio. The proposed antenna provides excellent VSWR of 1.208 and a gain of 5.960 dB. The simulated directivity, return loss (S11) and radiation efficiency are 6.015 dBi, -20.49 dB and 98.14% respectively. The simulation and PCB design of the proposed antenna are carried out using FR4 (lossy) substrate. The experimental radiation pattern is investigated using wave and antenna training system (WATS 2002) module. Finally, the simulated radiation pattern is compared with the experimental one.
Antenna Design
Computer Simulation Technology (CST) Microwave
Studio is used for antenna simulation and optimization.
Commercially available FR4 substrate of thickness 2.5 mm
is used on which the total structure is mounted. Dielectric
constant (ϵ) is chosen 4.3 while loss tangent is 0.025. The
opposite side of the substrate contains the copper plate that
acts as a ground plane. This enhanced the directivity of the
antenna to the desired level. Copper metal is also used as the
radiating element. The thicknesses of both the radiator and
ground plane are 0.313 mm. Plan view of the centimeter
wave microstrip patch antenna is shown in “Fig. 1”. Here,
the proposed dual-band antenna is designed and optimized
with first resonance frequency band at 1 r
f = 9.868 GHz and
second resonance frequency band at 2 r
f = 12.3-13 GHz on FR4 substrate. The overall ground plane dimension of the
proposed antenna is 40 × 39 mm2.
Fig shows the front and back view of the
hardware implementation of the proposed antenna. The
hardware design of the antenna is done using toner transfer
process.
The designed antenna provides resonance at frequencies at =
9.868 GHz and second resonance frequency band at = 12.3
13 GHz. The excitation signal to the antenna is supplied by
a 50Ω waveguide port using CST simulation software. From
the “Fig. 4” it can be seen that the return loss at first
resonance frequency is -20.49 dB and at the second resonance frequency is -10 dB. The proposed antenna
provides 3 dB impedance bandwidth at first resonance
frequency is 300 MHz ranging from 9.8 GHz to 10.1 GHz
and -8 dB bandwidth at the second resonance frequency is 1
GHz ranging from 12.2 GHz to 13.2 GHz. The simulated
VSWR curve of the proposed antenna is shown in “Fig. 5".
In a practical scenario, the VSWR is 1.1 to 2.5 and S
parameter range is less than -10 dB respectively although
the ideal value of VSWR is unity. In our designed antenna
the VSWR is less than 1.5 and S-parameter is less than
10dB. “Fig. 8” & “Fig. 9” shows the polar plot of radiation
pattern (both gain and directivity) of the proposed antenna
which indicates that the side lobe level is -7.6 dB, main lobe
magnitude is 5.8dB and 3dB angular width is 40 degree at
resonance frequency 9.968 GHz.
The variation of the resonance frequency, VSWR, gain and
return loss due to the variation of antenna arm length
(Arm3) are shown in “Fig. 11”.