上海天文台 Shanghai Astronomical Observatory RFI Environment at the Shanghai Sheshan Site Zhi-Qiang Shen, Bin Li, and Tao An (Shanghai Astronomical Observatory) “RFI RFI Mitigation Workshop” March, 2010, Groningen (NL)

上海天文台 Shanghai Astronomical Observatory Major Facilities for RA in China Delingha 13.7m 21CMA

上海天文台 Shanghai Astronomical Observatory Telescope site （ km away ） Headquarter of ShAO Location of the Shanghai Sheshan Site

上海天文台 Shanghai Astronomical Observatory Diameter: 25m Band: L, S/X, C, K VLBI Recording system: MK4, MK5A, MK5B Shanghai Sheshan 25m RT (1987)

上海天文台 Shanghai Astronomical Observatory Location 5 多波束射电接收时代的天体物理 南京 2009 年 9 月 6.1 KM 4 KM 2.4 KM 25m RT 65m RT

上海天文台 Shanghai Astronomical Observatory Shanghai 65m Radio Telescope  65-m in diameter fully steerable radio telescope  Active surface  Cover 1.4 – 46 GHz with 8 bands ： L(1.6GHz) S/X(2.3/8.4GHz) C(5GHz) Ku(15GHz) K(22GHz) Ka(30GHz) Q(43GHz)  General-purpose (radio astronomy, geodynamics, single- dish, VLBI ) 6

上海天文台 Shanghai Astronomical Observatory  Frequency coverage: 1.4~46 GHz  Aperture Efficiency ： L/S/C >60%, X >55%, Ku >40%, K >20% Ka >50%, Q >45% (with active surface)  Surface accuracy ： 0.6mm RMS (without active surface) 0.3mm RMS (with active surface)  Pointing accuracy ： 3 arcsec (wind < 4m/s) 10 arcsec (wind < 10m/s) 30 arcsec (wind < 20m/s)  First secondary lobes: <20 dB under main  Elevation limits: 5~90 degree  Slew rates: 0.5 degree/s (azimuth), 0.3 degree/s (elevation) Telescope Specifications 7

上海天文台 Shanghai Astronomical Observatory Receiver Specifications Band Frequency Range (GHz) Bandwidth (GHz) BW/CF (%) Polarization T REC (K) T LNA (K) L (18 &21cm) 1.25 ～ Lin/Circ10< 5 S (13cm) 2.15 ～ Circ12< 5 C (5 &6cm) 4.50 ～ Lin/Circ16< 5 X (3.6cm) 8.00 ～ Circ15< 5 Ku(2.2cm) ～ Circ15< 6 K (1.3cm) ～ Circ21< 10 K a(9mm) ～ Circ25< 12 Q(7mm) ～ Circ40< 18 Note: S/X and X/Ka are dual-frequency bands 8

上海天文台 Shanghai Astronomical Observatory  2008 ： funded, contract to CETC54 for the antenna construction  2009: complete design, start manufacturing  2010: foundation completed  2011: antenna completed  2012: L/S/C/X band test observations, ready for participation in the Chinese Lunar Mission  : active surface tested, Ku/K/Ka/Q band test observations  2015: project finished Project Timeline 9

上海天文台 Shanghai Astronomical Observatory 10 多波束射电接收时代的天体物理 南京 2009 年 9 月

上海天文台 Shanghai Astronomical Observatory L 波段的详细测试图 LNA =40dB. 1200MHz~1520MHz ，测试天线水平极化，以下四附图依次为天线指向东南西北四个方向测到的频谱图  L: 1.25 ～ 1.80GHz 1.25—1.52 GHz East South West North

上海天文台 Shanghai Astronomical Observatory  L: 1.25 ～ 1.80GHz 1.52—1.80 GHz

上海天文台 Shanghai Astronomical Observatory  S: 2.15 ～ 2.45GHz C:4.5 ～ 7.0 GHz

上海天文台 Shanghai Astronomical Observatory  C:4.5 ～ 7.0 GHz X:8.0 ～ 9.0 GHz

上海天文台 Shanghai Astronomical Observatory  9.2 ~ 17.8 GHz

上海天文台 Shanghai Astronomical Observatory Active surface control  Compensate (repeatable) gravitational deformations, to maintain the nominal shape of the primary reflector (to improve the efficiency at high frequencies)  Used on the USA GBT 100-m and Italy Noto 32-m 16

上海天文台 Shanghai Astronomical Observatory EMC testing with 300kg load 17

上海天文台 Shanghai Astronomical Observatory Results from EMC testing 18 Power-on & in motionPower-on & hold still

上海天文台 Shanghai Astronomical Observatory solutions  Administrative level: Shanghai Radio Administration Bureau Was done in 1990’s Good contact  Hardware: Superconductor filter Shielding etc  Software: learned from this workshop 19

上海天文台 Shanghai Astronomical Observatory Superconductor Filter  Mitigate strong RFI which saturates the first cryogenic LNA.  Working at 10~20K, low loss, low phase degeneration. Example  Frequency: 2.2~2.3GHz (3G mobile 2.14GHz)  Style: hairpin, 12 sections  Material: thin film TL-2212  Insertion loss: 0.05dB at 20K 20

上海天文台 Shanghai Astronomical Observatory Superconductor Filter Provided by CETC-16 institute 21

上海天文台 Shanghai Astronomical Observatory Conclusions and Future Work  RFI has become an important issue to the sites of radio telescopes in China  Observatory will pay close attention to both the technical and regulatory issues related to RFI  Superconductor filter (considered for 65m)  Shielding (under consideration)  Softwares  …  Spectrum management at different levels  Origins of RFI (Shanghai Radio Administration Bureau)  More frequent RFI monitoring is necessary to ensure a reliable assessment at Shanghai Sheshan site 22