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.

Diagonal Fed Nearly Square MSA L 1 = 3cm, Feed position = (0.15 L 1, 0.15 L 2 ) L 2  r = 2.55, h = 0.159cm and tan δ = 0.001 L 1 Input impedance, VSWR and AR plots for three values of L 2 : ( - - - ) 2.9, ( —— ) 2.92, and ( – - – ) 2.95 cm - LHCP

Nearly Square Ring MSA Nearly square ring MSA with (a) coaxial feed and (b) quarter-wave transformer.

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.

Compact CP Square MSA with Slits (a) (b) (a)SMSA with two pairs of unequal slits and (b)SMSA with corners chopped and four bent slits Application – GPS (1575 + 10 MHz) antenna, RHCP

Compact CP CMSA with Slits (b) (a) (c) (d) (e) 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

Gap-Coupled Broadband CP MSA (a) (b) (a) Three gap-coupled and (b) five gap-coupled square patches with orthogonal feeds for CP

Stacked Broadband CP SMSA (b) (a) (a) Top and (b) side views of two stacked square patches

Aperture- Coupled Broadband CP MSA (a) (b) (a) Square patch with two orthogonal cross slots of unequal lengths and (b) its measured input impedance plot.

CP Array using Linearly Polarized Elements Two linearly polarized rectangular patches with 90 ° rotation and phase difference of 0 ° , 90 ° , 180 ° , and 270 °

2-Elements Sequentially Rotated Array using CP MSAs (a) (b) (a) Sequentially rotated array of two CP circular elements and (b) superimposed CP response of the two elements

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 ° .

CP Array using CP Elements – VSWR and AR 2 × 4 arrays of circular patches with two notches: conventional and sequentially rotated. Measured VSWR and AR plots ( - - - ) conventional and ( —— ) sequentially rotated.

Microstrip Antenna Arrays Prof. Girish Kumar Electrical Engineering Department, IIT Bombay gkumar@ee.iitb.ac.in (022) 2576 7436

MSA Array Feed Networks  Series Feed  Corporate (Parallel) Feed  Series and Corporate Feed Series Feed Corporate Feed Advantages : Advantages: • Reduced feed length • Equal power to all element • Reduced losses • Larger BW • Lower Sidelobe • Modular in nature Disadvantages: Disadvantages: • Beam tilt with Frequency • Higher Feed losses • Narrow BW • Higher cross polar

Series Fed MSA Array λ/2 connecting line Patch Elements Value (mm) Antenna at Ka-Band Patch Length (pl) 2.68 RT 5880 substrate: Patch Width (pw) 3.2 ε r = 2.2, h = 0.254mm Connecting line 2.77 and tanδ = 0.0015 length (cl) Connecting line 0.4 width (cw) Space between 5.45 patches

23 × 1 Series Fed Array at Ka Band |S 11 | Plot Input Impedance Plot BW for |S 11 |  -10dB-35.9 to 38 GHz (5.6%) Gain: 19dB at 36 GHz 17 Gain vs Frequency plot Radiation Pattern at 36GHz

13x1 Series Fed MSA Array at 5.8 GHz Patch Length = 16.84mm BW for Patch width = 12.7mm VSWR < 2 is Feed line length = 18.85mm 5.78 to 5.94 GHz Inter element spacing = 0.6 λ o Max Gain at 5.82 GHz is ≈17 dB Radiation Pattern at 5.8GHz

7x1 Series Fed MSA Array at 5.8 GHz Fabricated 7-element series-fed Array Gain vs. Frequency Plot VSWR vs. Frequency Plot

Comparison of Central feed with End feed MSAA ( Central Feed, End Feed ) VSWR vs. frequency Gain vs. frequency plot

Comparison of Central feed with End feed (Cont.) 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 (a) (b) (c) Radiation Pattern at (a) 5.73, (b) 5.78 and (c) 5.83 GHz

Corporate Feed Planar MSA Array at X-Band Input Impedance Plot X-band antenna designed at f = 8.75 GHz Substrate: RT Duroid 5880 ( ε r = 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 (0.67λ 0 )

Corporate Feed 2x2 MSA Array Results Radiation Pattern BW for VSWR ≤ 2 is at 8.75 GHz more than 500 MHz

8x8 Corporate feed MSA Array