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XX--Band Horn Antenna Design Band Horn Antenna Design at RRSat RRS
W W SteynSteyn, , Reutech Reutech Radar SystemsRadar Systems
Innovative solutions Innovative solutions ……AffordableAffordable…….Available.Available
Overview
Antenna Background and SpecificationHorn RadiatorSub-Plank Feed DesignSub-Plank MeasurementFull Plank Feed DesignFull Plank MeasurementConclusion
Background and Specification
F1
F36
Receiver Signal Data ProcReceiver Signal Data Proc
Receiver Signal Data ProcReceiver Signal Data Proc
Receiver Signal Data ProcReceiver Signal Data Proc
Receiver Signal Data ProcReceiver Signal Data Proc
Receiver Signal Data ProcReceiver Signal Data Proc
Receiver Signal Data Proc
TWTATiming
SynthesizerWafeform Generator
Upconverter
TX B
eam
form
er
Plan
k El
ectro
nics
CombinationExtractor
Radar Manager
N=36D=0.5λ
RX
Bea
mfo
rmer
36 Receiver/processors4 Degree beamwidth
F1
3D Stacked Beam
Background and Specification
Vertical polarisationRX elevation beamwidth: > 70°Azimuth beamwidth: 1°, Side-lobe level: -30dBS11 < -10dB20% Bandwidth: 8.5 – 10.5GHz
20 Km 30 Km 40 Km 50 Km10 Km 20 Km 30 Km 40 Km 50 Km
10 000m
10 Km
30 Degr
8000M
70 Degr
Cover Diagram
1 Sq MSwerling 180% Pd1 EXP -6 PFA
1 Sq MSwerling 180% Pd1 EXP -6 PFA
Horn Radiator
E-plane sectoral horn very simple structure: 21x15x50mmBeamwidth > 70°Reflection coefficient good (<-15dB)
Sub-Plank Feed Design
Must be a squintless feed – equal phase12-Way E-Plane divider – Marconi Review 1972
Design built on isosceles trianglesWell-suited to horizontal polarisation
Sub-Plank Feed Design
Amplitude deviation < 0.8dBPhase deviation < 4°S11 < -17dBWaveguide twistsection required forvertical polarisation
Sub-Plank Feed Design
Machineable waveguide twist – Lenzing 199090° rotation of E-plane through L-shaped waveguideDesign L-shaped waveguide to have the same cut-off frequency as input waveguide.Twist 100mm long
Sub-Plank Feed Design
Sub-plank manufactured from Aluminium using CNC machining and wire-cutting.
Gain 15-16.5dB
Sub-Plank Measurement
Sub-Plank Measurement
Full Plank Feed Design
96 Elements – 16 banks of 6 uniform excitationsStart with Villeneuve Distribution for 16 elements, 5 close-in elements, 40dB sidelobesUniform banks produce quantization lobes at –30dB
Full Plank Feed Design
96 Elements – 16 banks of 6 linear excitationsLinear banks produce quantization lobes at –35dB
Full Plank Feed Design
1
0.5 0.5
0.121 0.8790.0604
0.129 0.871
0.440
0.370 0.630
0.277
0.5330.4670.6030.3970.6880.3120.7440.256
0.0078 0.0526 0.163
0.0020 0.0058 0.0164 0.0362 0.0647 0.0984 0.1291 0.1474
1
2
32
4 5 6 7
4 LevelsDivider 2 problematic5-stage transformer used to obtain good phase balance between output ports
Full Plank Feed Design
Full Plank Feed Design
Full Plank Measurements
Full Plank Measurements
From preliminary measurements on sub-planks the gain was expected to be 1 to 2dB low, especially at lower frequencies.Measurement uncertainties of ±1dB
Full Plank Measurements
Outside ±10° side-lobes below –30dBHighest close-in side-lobe –23dBBeamwidth correct
Conclusion
Designed, manufactured and tested 2.4m X-Band horn antenna plank20% bandwidth70° elevation beamwidthGood azimuth side-lobe performanceGain is low at lower frequenciesIt is way too heavy! Investigate alternative manufacturing processes
Thank YouThank You……
Innovative solutions Innovative solutions ……AffordableAffordable…….Available.Available