Wide-band Feeds DevelopmentWide-band Feeds DevelopmentG. SankarG. Sankar

Band: 250 – 500 MHz.Band: 250 – 500 MHz. Pranjal’s design: Dipole within a smallerPranjal’s design: Dipole within a smaller dia. of Cavity ; design formulated bydia. of Cavity ; design formulated by WiPL-D software.WiPL-D software.

MeasurementsMeasurements

Comparison of Std. Cavity backedComparison of Std. Cavity backed DipoleDipole

Std. CBDStd. CBD Pranjal’sPranjal’s

Cavity dia.Cavity dia. 1.07 * 1.07 * λλ 0.76*0.76*λλ

Cavity depthCavity depth 0.28*0.28*λλ 0.45*0.45*λλ

Std.Cavity Backed DipoleStd.Cavity Backed Dipole

Measurements of CBDMeasurements of CBD

Simulated vs. measuredSimulated vs. measured

Simulated Radiation parametersSimulated Radiation parameters

Simulated cross-polar levelsSimulated cross-polar levels

FeaturesFeaturesWeight : 23.0 kg.Weight : 23.0 kg. ( 20.0 + 1.5 + 1.5)( 20.0 + 1.5 + 1.5)

Cost : ~ Rs.26000 / feed.Cost : ~ Rs.26000 / feed.

Improved BW for 327 MHz. dipoleImproved BW for 327 MHz. dipole

Existing vs. ModifiedExisting vs. Modified

Simulated Radn.parametersSimulated Radn.parameters

Existing / ModifiedExisting / Modified

Impedance BW: Impedance BW: 292 – 469 MHz.292 – 469 MHz. (177 MHz.)(177 MHz.)

Polariz. BW :Polariz. BW : 275 – 350 MHz. 275 – 350 MHz.

Impedance BW :Impedance BW : 289 – 524 MHz.289 – 524 MHz. (235 MHz.)(235 MHz.)

Polariz. BW:Polariz. BW: 260 – 375 MHz.260 – 375 MHz.

Available choices …Available choices … Install 250 MHz.CBD on 2 antennas & testInstall 250 MHz.CBD on 2 antennas & testScale the 250 MHz. CBD design to lowerScale the 250 MHz. CBD design to lower freq. band : 120 – 240 MHz.freq. band : 120 – 240 MHz.Modified 327 Dipole – install in 10 Modified 327 Dipole – install in 10

antennas.antennas.New designs – Conical cavity + Dipole :New designs – Conical cavity + Dipole : explore.explore.

Budget Estimate (2010-2011)Budget Estimate (2010-2011)10 nos. of (250 MHz.CBD) : 3.0 lac10 nos. of (250 MHz.CBD) : 3.0 lacAntenna Range : 8.0 lacAntenna Range : 8.0 lacHardware & Software : 1.0 lacHardware & Software : 1.0 lacCST Microwave Studio : 30 lacCST Microwave Studio : 30 lac

Total : 42 lacTotal : 42 lac

Long-term goalsLong-term goals

‘‘LIGHT WEIGHT’ designs forLIGHT WEIGHT’ designs for 550 – 800 MHz.550 – 800 MHz.

New L-Band feed design withNew L-Band feed design with cryogenics.cryogenics.

AcknowledgementAcknowledgement

Hanumanth Rao.B.Hanumanth Rao.B.

NCRA Workshop TeamNCRA Workshop Team FE – Lab. colleaguesFE – Lab. colleagues

… … on a lighter vein …on a lighter vein …

Science is always wrong. It never solves aScience is always wrong. It never solves a problem without creating ten more.problem without creating ten more. : G.Bernard Shaw.: G.Bernard Shaw.