EVLA Feed/FE PDR

1
EVLA Polarizers for X, Ku, K and Ka Bands

• S. Srikanth
• NRAO/Charlottesville

2
Circular Polarization
3
Circular Polarization
4
Contours of Constant Axial Ratio vs. Amplitude
and Phase Error
5
Septum Polarizer
6
Septum Polarizer
7
Septum Polarizer12-15.4 GHz
Return Loss
Deviation of ?? from 90
8
Conventional Polarizer
9
Mode Combiner/Splitter(18-26.5 GHz)
10
OMT 18-26.5 GHz
Boifot et. al., Proc. IEE, vo1. 137, Dec.
'90. Wollack, EDIR 303, May '96.
11
Phase Shifter
12
Phase Shifter(a) Dispersion characteristics
(b) Differential phase shift vs. the frequency
13
Corrugated/Dielectric Phase Shifter(a)
Dispersion characteristics (b) Differential
phase shift vs. the frequency
Lier et. al., IEEE MTT, vol. 36, Nov. '88.
14
Corrugated Phase Shifter
15
NRAO Phase Shifter(18-26.5 GHz)
Srikanth, IEEE Microwave Guided-Wave Ltrs.,
vol. 7, June '97.
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NRAO Phase Shifter (18-26.5 GHz)
17
NRAO Phase Shifter (18-26.5 GHz)Measured ??
Differential Phase Shift
18
NRAO Phase Shifter (18-26.5 GHz)Measured S11,
S12
Return Loss
Insertion Loss
19
NRAO Phase Shifter(26.5-40 GHz)
20
NRAO Phase Shifter (26.5-40 GHz)Measured ??
Differential Phase Shift
21
NRAO Phase Shifter(26.5-40 GHz) Measured S11,
S12
Return Loss
Insertion Loss
22
EVLA Phase Shifters