Applying a Composite Pattern Scheme to Clutter Cancellation with the Airborne POLARIS Ice Sounder Keith Morrison 1 , John Bennett 2 , Rolf Scheiber 3 [email protected]1 Department of Informatics & Systems Engineering Cranfield University, Shrivenham, UK. 2 Private Consultant, UK. 3 Microwaves and Radar Institute German Aerospace Research Center , Wessling, Germany.
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Applying a Composite Pattern Scheme to Clutter Cancellation with the Airborne POLARIS Ice Sounder
Applying a Composite Pattern Scheme to Clutter Cancellation with the Airborne POLARIS Ice Sounder Keith Morrison 1 , John Bennett 2 , Rolf Scheiber 3 [email protected] 1 Department of Informatics & Systems Engineering Cranfield University, Shrivenham , UK. - PowerPoint PPT Presentation
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Applying a Composite Pattern Scheme to Clutter Cancellation with the Airborne POLARIS Ice
ESA-ESTEC Contract: 104671/11/NL/CT Nico Gebert Chung-Chi Lin Florence Heliere
PRESENTATION
• Problem• Composite Pattern
- convolution - array polynomial
• Application• Results
H
dhr
ice
bedrock
air
RR
z
POLARIS
PROBLEM
Geometric alignment and dimensions of the 4 independent receive apertures of the POLARIS antenna
ANTENNA ARRAY
Test-ID Bandwidth
[MHz]
Remarks
p110219_m155222_jsew1
85 & 30 MHz From east: grounded ice, then crossing the glacier tongue, frozen grounded ice in the
middle, ice shelf in the westp110219_m155222_jswe1 85 & 30 MHzp110219_m155222_jsns1 85 & 30 MHz cross-track slopes with
grounded icep110219_m180339_jsns2 85 & 6 MHz profile along the glacier
tongue
ICEGRAV 2011
PROCESSING SCHEME
Rx Pattern
Rx Array & Element Pattern
• Phased-array nulling traditionally optimizes performance by utilising available array elements to steer a single null in the required direction.
• However, here we exploit the principle of pattern multiplication.
• With different element excitations, nulls in differing angular directions are generated.
• Composite array is produced by the convolution of two sub-arrays.
• The angular response of the composite array is the product of those generated by the individual sub-arrays.
COMPOSITE ARRAY
CONVOLUTIONThe building block is the 2-element array.
To generate a null at angle θA the excitation of the array is required to be:
Similarly to generate a null at angle θB the excitation of the array is required to be:
1.0
1.0
3-ELEMENT : 2-Null
To preserve these nulls we must generate the product of the two patterns and this is achieved by convolving the two distributions to give the following 3-element distribution:
1 a+b ab
where: a = -exp[jkdsinϴA] b = -exp[jkdsinϴB]
4-ELEMENT : 2-Null
1 a b0 ab0
where: a = -exp[jkdsinϴA] b = -exp[jkdsinϴB] b0=-exp[jk2dsinϴB]
4-ELEMENT : 3-Null
To generate a third null at angle, θC, requires convolution of the result from the 3-element, 2-null case with an additional 2-element array, with the distribution: