Microstrip Patch Antenna Design for Ku Band Application

Microstrip Patch Antenna Design for Ku Band Application

Vijaykumar V. Chodavadiya

Department of Electronics and Communication Engineering School of Engineering, RK.University,

Rajkot, Gujarat, India.

Shivani S. Aggarwal

Department of Electronics and Communication Engineering School of Engineering, RK.University,

Rajkot, Gujarat, India.

AbstractMicrostrip Patch Antenna is designed for Ku band 12GHz to 18GHz. The proposed antenna on a Teflon substrate with dielectric constant 2.1. At resonant frequency 12.54GHz the verify and tested result on CST Microwave Studio by CST STUDIO SUIT are Return loss = -26.5578 dB, Voltage Standing Wave Ratio = 1.0986392, Gain = 6.906dB, Directivity = 6.976dBi, Bandwidth = 4.1553GHz (33.14%) and Efficiency = 98.99%, all results are shown in simulation results.

KeywordsCST Microwave Studio, Microstrip Patch Antenna, Ku band.

Step 1: Calculation of the Width (W):

(1)

Where, c = 3 x 108 m/s, r=2.1, fr = Designed Frequency Step 2: Calculation of Effective dielectric constant (reff ):

(2)

1. INTRODUCTION

   This Microstrip antenna have been one of the most innovative topics in antenna theory and design in recent years, and are increasingly finding application in a wide range of modern microwave systems [6]. Deschamps first proposed the concept of the MSA in 1953 [2]. However, practical antennas were developed by Munson [3]-[4] and Howell [5] in the 1970s. Microstrip antennas (MSA) offer many attractive features such as low weight, small size, ease of fabrication, ease of integration with Microwave Integrated Circuits (MIC) and can be made conformal to host surface. However, they suffer from low gain, narrow bandwidth, low efficiency, and low power handling capability [7]-[9]. In some applications, such as in government security systems, narrow bandwidths are desirable [7]. This proposed antenna has rectangular patch used. The rectangular patch is by far the most widely used configuration. It is very easy to analyze using both the transmission-line and cavity models, which are most accurate for thin substrates [7].

2. ANTENNA DESIGN

   A. Mathematical Analysis

   The design of the proposed antenna is shown in Fig.1 and Fig 2. The design of the proposed microstrip patch antenna was modeled using the classical equations [7].

   Where, h = 0.8 mm

   Step 3: Calculation of the Effective length (Leff ):

   Step 4: Calculation of the length extension (L):

   Step 5: Calculation of actual length of patch (L):

   Antenna Description

   (3)

   (4)

   (5)

   Slit in main patch (x, y)	(4.82, 0.4) mm
   Main Patch(x, y)	(9, 4.5) mm
   Parasitic Patch 1 (x, y)	(5.2, 4.5) mm
   Parasitic Patch 2 (x, y)	(5, 4.5) mm
   Feed location (Xf, Yf) from(0, 0)	(2.9, -0.6) mm
   Co-axial Cable Type	Inde P-Trim
   Feed Diameter	1.2mm

   All dimensions are in millimeter (mm)

   Fig.1. Top view of the Microstrip Patch Antenna

   (mm)

   All dimensions are in millimeter

   Fig.2. Left side view of the Microstrip Patch Antenna

3. RESULT AND DISCUSSION

   The simulated return loss (S1,1) of the proposed antenna is depicted in Fig.4 and Fig.5. The graph shows the maximum return loss of -26.5578dB at the resonant frequency 12.54GHz. The graph also depicts that below -10dB the antenna attained the bandwidth of 4.1553GHz (33.14%) which is 13% more bandwidth achieved than bandwidth achieved in [14].

   The voltage standing wave ratio (VSWR) of the proposed antenna shown in Fig.6. It can be observed from the result that the VSWR value is less than 2 for whole operating band,

   The proposed microstrip patch antenna at designed frequency 14 GHz on Teflon dielectric substrate simulated with CST MW STUDIO simulator. Proposed antenna has good gain and bandwidth achieved if L = 9 mm and W = 4.5 mm with feed position change to Xf = 2.9 mm in X direction and Yf = -0.6 mm in Y direction from origin (x=0, y= 0). Also parasitic patch 1 and parasitic patch 2 cause wide bandwidth is achieved. Fig.3 shows Microstrip patch antenna designed using CST Microwave Studio.

   Fig.3. Microstrip patch antenna designed using CST Microwave Studio

   The antenna is being excited with the coaxial feed point located at distance dx and dy from the centre of the patch. The following Table 1 gives the design parameter specifications of the Microstrip Antenna.

   TABLE 1

   Dielectric Constant of the Substrate (r)	2.1-Teflon (PTFE)
   Height of the dielectric substrate (h)	0.8 mm
   Height(t) of Patch and Ground	0.035 mm
   Patch (Length(L) ,Width(W))	(23.2, 4.5) mm
   Substrate and Ground (Length, Width)	(40, 10) mm
   Design Frequency(fr)	14 GHz

   DESIGN PARAMETER SPECIFICATIONS OF THE RECTANGULAR MICROSTRIP PATCH ANTENNA

   which considered as suitable for the antenna.

   Fig.7 and Fig.8 depict far field radiation directivity and far field radiation gain of proposed antenna respectively. Directivity and Gain is 6.976 dBi and 6.906 dB respectively. Fig.9 and Fig.10 shows structure with far-field transperent. Beanwidth is 104.7° at 3dB. Table 2 shows the summary of results of the microstrip patch antenna.

   Fig.4. Return Loss vs. Frequency

   Fig.5. Return Loss vs. Frequency

   Fig.6. VSWR vs. Frequency

   Fig.7. Directivity at 12.54 GHz

   Fig.8. Gain at 12.54 GHz

   Fig.9. Structure with far-field transperent at 12.54 GHz

   Fig.10. Structure with far-field transperent at 12.54 GHz TABLE 2

   MICROSTRIP PATCH ANTENNA PARAMETERS

   Return loss (S1,1)	-26.5578 dB
   Directivity(D)	6.976 dBi
   Gain (G)	6.906 dB
   Radiation Efficiency()	98.99 %

4. CONCLUSIONS

The proposed frequency range at 14GHz and analysis Radiation Characteristics of microstrip patch antenna by CST STUDIO SUIT. The proposed antenna on a Teflon substrate with dielectric constant 2.1. At 12.54GHz resonant frequency the verify and tested result on CST Microwave Studio by CST STUDIO SUIT are Return loss = -26.5578 dB, VSWR = 1.0986392, Directivity = 6.976 dBi, Gain = 6.906 dB, Bandwidth = 4.1553 GHz (33.14 %) (at S1,1 < -10dB and VSWR < 2), Efficiency= 98.99 % and Beamwidth at 3dB = 104.7°, all results shown in simulation results. Very thin slit or slot in the patch cause Bandwidth and Return loss (S1,1) is improved. Parasitic patch cause wide bandwidth is achieved. Also 13% more bandwidth achieved than bandwidth achieved in [14]. The future scope of work revolves around increasing the gain up to 28dB – 30 dB by modifications in design and making array of the same proposed patch antenna. Detailed theoretical explanations can be derived at a later stage to find out a best optimize design with proper dimensions of the notches and strip of proposed antenna.

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