development of q-band two-beam cryogenic receiver of
TRANSCRIPT
Development of Q-Band Two-Beam Cryogenic Receiver of Tianma TelescopeWei-Ye ZHONG on behalf of Tianma Q-Band Receiver TeamOct.15, 2015
Shanghai Astronomical Observatory, CASHttp://www.shao.ac.cn
2
Outline
Introduction of Q-band cryogenic receiver over the world
Tianma Q-band receiver diagram and specification
Quasi-optics design
Feed network design and test
Cryogenic LNA test at room temperature and cryogenic test bench
Cold cartridge assembly and test
Future work and schedule
3
Specification of Q-band cryogenic receiver over the world
Telescope Freq (GHz) Beam Pol Technology Trx (K) Year Remark
Nobeyama 45m 40-50 6 Linear SIS mixer 40 1998 Observation
GBT 100m 38.2-49.8 4 Circular HEMT amp 20～45 2007 Observation
EVLA 25m 40-50 1 Circular HEMT amp 48 2006 Observation
ATCA 22m 30-50 1 Circular HEMT amp 40 2007 Observation
KVN 21m 42-44 1 Circular HEMT amp 50 2007 Observation
Effelsberg 100m 41.0-49.7 2 Linear HEMT amp 60～70 2008 Observation
ALMA 13m 35-50 1 Linear HEMT amp 26～33 2018 In progress
SRT 64m 33-50 19 Circular HEMT amp 40 TBD In progress
Tianma 65m 35-50 2 Circular HEMT amp 40 2015 This work
Note: The noise temperature of existing Q-band cryogenic receiver over the world is 40～70K
4
Tianma Q-band receiver noise budget and specification
Item Specification
Frequency Band 35-50 GHz
Number of Beams 2
TRX < 40 K
Gain ~ 60 dB
Polarization dual, circular(AR≤ 1dB)
Polarization Isolation
> 25 dB
LO (1st) 31-38 GHz
IF Frequency (1st) 4-12 GHz
Headroom >30 dB (to P1dB)
P-1dB +10 dBm
5
Quasi-optics of Q-band feed in Tianma Telescope
Feed Spacing(mm)
Beam Spacing(arcsec)
Unit of HPBW Remarks
Single Pixel 27.4” 1
60 86.4” 3.2
70 100” 3.7 Our Choice
80 113.8” 4.2
100 144” 5.3
-300 -200 -100 0 100 200 30010
20
30
40
50
60
70
80
90
100
[arcs]
Rad
iatio
n P
atte
rn [d
Bi]
Single Pixel 43GHzSymmetry D=60mm 43GHzSymmetry D=70mm 43GHzSymmetry D=80mm 43GHzSymmetry D=100mm 43GHzSymmetry D=120mm 43GHzSymmetry D=140mm 43GHz
Single-Beam Spacing=70mm
-300 -200 -100 0 100 200 30010
20
30
40
50
60
70
80
90
100
[arcs]
Rad
iatio
n P
atte
rn [d
Bi]
Symmetry 70mm 35GHzSymmetry 70mm 43GHzSymmetry 70mm 50GHz
Spacing=50mm Spacing=150mmRadiation pattern for spacing=70mm at 35GHz, 43GHz and 50GHz
6
Corrugated feed horn
Return loss test
7
Far-field radiation pattern measurement
Edge Taper: -18 to -12dB @ 13°on the rim of sub-reflector over the full-band
8
Noise injection directional coupler using circular waveguide
34 36 38 40 42 44 46 48 50
26
28
30
32
34
Cou
plin
g [d
B]
Frequency [GHz]
Measured Result Simulated Result
34 36 38 40 42 44 46 48 50-60
-50
-40
-30
-20
-10
0
R
ecta
ngul
ar W
aveg
uide
Ref
lect
ion
[dB]
Frequency [GHz]
Measured Result Simulated Result
Only one noise source will inject the LHCP and RHCP four channels with two beams simultaneously.
Assuming Tsys=100K，ENR=21，
IL =0.2+3.2+0.1+2+28=33.5 dB，ILswitch = 0.2dB, Ilpower divier =3.2dB, ILwg = 0.1dB,ILcoupler to Injector = 2dB,ILcoupling = 28dB,
Tsource=323×(10^(ENR/10)+1)=40986.3
Tinjection=18K，18%Tsys
9
90°phase shifter with two-wall corrugation
35 40 45 500
0.5
1
1.5
Freq [GHz]
Axia
l Rat
io [d
B]
35 40 45 50-0.25
-0.2
-0.15
-0.1
-0.05
0
0.05
0.1
0.15
Freq [GHz]
Inse
rtion
Los
s [d
B]
10
Ortho-mode transducer based on boifot-junction with double ridge
35 40 45 50
-0.4
-0.2
0
0.2
Freq [GHz]
Inse
rtion
Los
s [d
B]
Dual-Ridge Ortho-mode Transducer
Horizontal-PolVertical-Pol
Return loss
11
Feed network assembly and test
35 40 45 50-1
-0.8
-0.6
-0.4
-0.2
0
Freq [GHz]
Inse
rtion
Los
s [d
B]
IL: 0.4~0.6dB @ 300KNT: 3K @ 20K
12
Cold cartridge assembly and test
Preliminary test result with Q-band receiver noise temperature of 30-50K is achieved.
13
Future work and schedule
System stability will be tested.
The box of warm cartridge will be fabrication.
The installation mechanical structure in telescope will be fabrication.
Tianma Q-band cryogenic receiver will be commissioning on Dec. 2015.