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L1 L2 L L L L L
L1 L2
Various Single Feed CP MSAs L 2 (a) (b) (c) L 1 L L (d) (e) - - PowerPoint PPT Presentation
Various Single Feed CP MSAs L 2 (a) (b) (c) L 1 L L (d) (e) - - PowerPoint PPT Presentation
Various Single Feed CP MSAs L 2 (a) (b) (c) L 1 L L (d) (e) (f) L L L (a) Diagonal fed nearly square. Square with (b) two stubs, (c) two notches, (d) two corners chopped, (e) square notches at two corners, and (f) diagonal slot.
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Nearly square ring MSA with (a) coaxial feed and (b) quarter-wave transformer.
Nearly Square Ring MSA
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Variations of CMSAs and ETMSAs
(a) Elliptical MSA and CMSA with (b) two notches, (c) two stubs, and (d) a rectangular slot in the centre. (a) Nearly ETMSA, (b) tip-truncated ETMSA, (c)ETMSA with a rectangular slot, and (d) ETMSA with a notch.
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Compact CP Square MSA with Slits
(a)SMSA with two pairs of unequal slits and (b)SMSA with corners chopped and four bent slits
(a) (b)
Application – GPS (1575 + 10 MHz) antenna, RHCP
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Compact CMSA with (a) cross slot and (b) curved slot with tuning
- stub. Annular ring MSA with (c) an internal offset polarizer and
slits in the (d) outer and (e) inner circles
Compact CP CMSA with Slits
(a) (b) (c) (d) (e)
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Gap-Coupled Broadband CP MSA
(a) Three gap-coupled and (b) five gap-coupled square patches with orthogonal feeds for CP
(a) (b)
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Stacked Broadband CP SMSA
(a) Top and (b) side views of two stacked square patches (a) (b)
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(a) Square patch with two orthogonal cross slots of unequal lengths and (b) its measured input impedance plot.
(a) (b)
Aperture- Coupled Broadband CP MSA
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CP Array using Linearly Polarized Elements
Two linearly polarized rectangular patches with 90° rotation and phase difference of 0°, 90°, 180°, and 270°
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2-Elements Sequentially Rotated Array using CP MSAs (a) Sequentially rotated array of two CP circular elements and (b) superimposed CP response of the two elements
(a) (b)
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4-Elements Sequentially Rotated Array using CP MSAs Sequential array of four CP elements with 90° rotation and phase difference of 0°, 90°, 180°, and 270°.
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Measured VSWR and AR plots ( - - - ) conventional and ( —— ) sequentially rotated.
CP Array using CP Elements – VSWR and AR
2 × 4 arrays of circular patches with two notches: conventional and sequentially rotated.
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Microstrip Antenna Arrays
- Prof. Girish Kumar
Electrical Engineering Department, IIT Bombay
gkumar@ee.iitb.ac.in (022) 2576 7436
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MSA Array Feed Networks
Advantages :
- Reduced feed length
- Reduced losses
- Lower Sidelobe
Disadvantages:
- Beam tilt with Frequency
- Narrow BW
Advantages:
- Equal power to all element
- Larger BW
- Modular in nature
Disadvantages:
- Higher Feed losses
- Higher cross polar
- Series Feed
- Corporate (Parallel) Feed
- Series and Corporate Feed
Series Feed Corporate Feed
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Series Fed MSA Array
Antenna at Ka-Band
RT 5880 substrate: εr = 2.2, h = 0.254mm and tanδ = 0.0015 Elements Value (mm) Patch Length (pl) 2.68 Patch Width (pw) 3.2 Connecting line length (cl) 2.77 Connecting line width (cw) 0.4 Space between patches 5.45
Patch λ/2 connecting line
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17
|S11| Plot Input Impedance Plot Radiation Pattern at 36GHz Gain vs Frequency plot
BW for |S11| -10dB-35.9 to 38 GHz (5.6%)
23×1 Series Fed Array at Ka Band
Gain: 19dB at 36 GHz
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13x1 Series Fed MSA Array at 5.8 GHz
BW for VSWR < 2 is 5.78 to 5.94 GHz Max Gain at 5.82 GHz is ≈17 dB Radiation Pattern at 5.8GHz Patch Length = 16.84mm Patch width = 12.7mm Feed line length = 18.85mm Inter element spacing = 0.6λo
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Fabricated 7-element series-fed Array
7x1 Series Fed MSA Array at 5.8 GHz
VSWR vs. Frequency Plot Gain vs. Frequency Plot
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( Central Feed, End Feed ) VSWR vs. frequency Gain vs. frequency plot
Comparison of Central feed with End feed MSAA
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(a) (b) (c) Radiation Pattern at (a) 5.73, (b) 5.78 and (c) 5.83 GHz
- S. No.
Parameters Central Feed End Feed 1 VSWR <2 Bandwidth (MHz) 100 141 2 Maximum Gain (dBi) 14.8 14.5 3 E-plane HPBW at 5.73 GHz (degrees)
- 7.2 to 7.2
- 4.3 to 9.7
4 E-plane HPBW at 5.78 GHz (degrees)
- 6.7 to 6.8
- 2.2 to 10.6
5 E-plane HPBW at 5.83 GHz (degrees)
- 6.3 to 6.3
0.7 to 12.7 6 Cross-polar levels (dB) 35 20
Comparison of Central feed with End feed (Cont.)
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Corporate Feed Planar MSA Array at X-Band
X-band antenna designed at f = 8.75 GHz Substrate: RT Duroid 5880 (εr = 2.2, h = 1.59 mm and tanδ = 0.001) Patch Length = 13.23 mm, Patch Width = 10.17 mm Inter element spacing in the E and H planes = 23 mm (0.67λ0) Input Impedance Plot
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BW for VSWR ≤ 2 is more than 500 MHz Radiation Pattern at 8.75 GHz
Corporate Feed 2x2 MSA Array Results
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