High Temperature Superconductor Filters for Sardinia Radio Telescope INTRODUCTION Why a Filter? HTS FILTRES The Process HTS FILTERS Examples NEXT STEPS CONCLUSIONS P. Bolli1, L. Cresci1, F. Huang2, S. Mariotti3 D. Panella1 INAF-Osservatorio Astrofisico di Arcetri – Firenze - ITALY School of EECE, University of Birmingham, Edgbaston, Birmingham UK INAF-Istituto di Radioastronomia – Bologna ITALY Detection and measurement of RFI on radio astronomy – Yebes 8-9 June 2017

INTRODUCTION Why a Filter? HTS FILTRES The Process Given a radio receiver chain, in order to reject RFI, a band pass filter and/or a notch may be placed just after LNA. After LNA with typical Gain 35…40 dB, the increase of Tsys is negligible. INTRODUCTION Why a Filter? HTS FILTRES The Process HTS FILTERS Examples NEXT STEPS CONCLUSIONS Usually RFI became dangerous for receiver linearity at the end of the chain (mixer, IF Amp, final stage). RFI is every time blinding, but if linearity will be affected, even the software mitigation will fails. So, why a front-end filter? Detection and measurement of RFI on radio astronomy – Yebes 8-9 June 2017

INTRODUCTION Why a Filter? HTS FILTRES The Process The new frontier of RA calls for large bandwidth (1octave) or very large, as the case of BRAND-EVN ( 1 decade). INTRODUCTION Why a Filter? HTS FILTRES The Process HTS FILTERS Examples NEXT STEPS CONCLUSIONS For many years, usual and common LNA had a Po1 ~+5 dBm. An emerging brand sells excellent LNA but with Po1 ~ -12 dBm (C-band) Given this conditions, if radar(s) or strong source(s) are located near the Radiotelescope, the risk of non linearity distortion will affect the LNA too. For this reasons a front-end filter may help Detection and measurement of RFI on radio astronomy – Yebes 8-9 June 2017

INTRODUCTION Why a Filter? HTS FILTRES The Process FILTER REQUIREMENTS The loss of the filter must not increase significantly the Noise Temperature. INTRODUCTION Why a Filter? HTS FILTRES The Process HTS FILTERS Examples NEXT STEPS CONCLUSIONS This mean the loss and the mismatch of the filter should be the lower as possible and Tsys still remain competitive. |s21| and |s12| : the lowest possible |s11| and |s22| : the lowest possible Detection and measurement of RFI on radio astronomy – Yebes 8-9 June 2017

HTS Filters appeared immediately as the best technological solution. ON THE FILTER LOSS HTS Filters appeared immediately as the best technological solution. Due to the extremely low loss, HTS Filter has been used as narrow band Filters. For such applications the low loss performances cannot be overcome. INTRODUCTION Why a Filter? HTS FILTRES The Process HTS FILTERS Examples NEXT STEPS CONCLUSIONS Even more, with wide band, we expect an extremely low loss.   LF (intedigital, 20K) ≈ 0.4 @ P Band LF (HTS, 20K) ≈ 0.04 @ P Band (due to MgO substrate – estimated value) Filter Loss [ dB ]   Tsys w/o filter [ K ] Tsys with filter 0.05 5 5.3 15 15.4 0.10 5.6 15.8 0.15 5.9 16.2 0.20 6.2 16.6 0.25 6.5 17.1 Detection and measurement of RFI on radio astronomy – Yebes 8-9 June 2017

INTRODUCTION Why a Filter? HTS FILTRES The Process THE FILTER Filter Design HTS furnisher INTRODUCTION Why a Filter? HTS FILTRES The Process HTS FILTERS Examples NEXT STEPS CONCLUSIONS Ti alloy Milling Layout Optimization Ti alloy house drawing Assembly and Test & measurement Ti alloy plating Detection and measurement of RFI on radio astronomy – Yebes 8-9 June 2017

INTRODUCTION Why a Filter? HTS FILTRES The Process HST STRUCTURE Ion Beam Milling GOLD 0.2 mm HTS (YBCO) 0.6 mm MgO Dielectric 500 mm GOLD 0.2 mm INTRODUCTION Why a Filter? HTS FILTRES The Process HTS FILTERS Examples NEXT STEPS CONCLUSIONS Detection and measurement of RFI on radio astronomy – Yebes 8-9 June 2017

INTRODUCTION Why a Filter? HTS FILTRES The Process HST DESIGN INTRODUCTION Why a Filter? HTS FILTRES The Process HTS FILTERS Examples NEXT STEPS CONCLUSIONS The filter may be band pass, low pass, high pass, notch or a combination of them The synthesis is based on original circuital solutions and layout geometry coming from the long experience of Lancaster’s group at Birmingham University. More deeply, the design method is based on coupling coefficients of intercoupled resonators and the external quality factors of the input and output resonators. Later , the geometry is fine tuned and analysed with Sonnet EM simulator Detection and measurement of RFI on radio astronomy – Yebes 8-9 June 2017

INTRODUCTION Why a Filter? HTS FILTRES The Process HST DESIGN The housing should firmly host the PCB. Excellent electrical contacts on both central pin and GND is required The mechanical design must be robust against differential of Coeff. Of Thermal Expansion INTRODUCTION Why a Filter? HTS FILTRES The Process HTS FILTERS Examples NEXT STEPS CONCLUSIONS Ti6 Al4 V is the alloy that match the CTE of MgO, both at room temperature and in cryogenic environment. In order to better match the CTE, a “gummous” epoxy is used. The Henkek Ablefilm 5025E – 4 mils is an electrical conductive, gommous, double-sided adhesive tape. Detection and measurement of RFI on radio astronomy – Yebes 8-9 June 2017

INTRODUCTION Why a Filter? HTS FILTRES The Process HST: ASSEMLING PHASE INTRODUCTION Why a Filter? HTS FILTRES The Process HTS FILTERS Examples NEXT STEPS CONCLUSIONS HTS C-Band : Assembling phase Detection and measurement of RFI on radio astronomy – Yebes 8-9 June 2017

INTRODUCTION Why a Filter? HTS FILTRES The Process HST TEST & MEASUREMENT Test & Measurement were made in parallel in two laboratories, Florence and Bologna   Bologna Lab. Florence Lab. VNA  cryogenic full 2 port calibration under refinement full 2 port calibration at room temperature, then correction of the cold path in post-processing. LOW DRIFT SNA good for fast test, but less accurate Radiometric Noise Possible but complicated and not more accurate than VNA INTRODUCTION Why a Filter? HTS FILTRES The Process HTS FILTERS Examples NEXT STEPS CONCLUSIONS Detection and measurement of RFI on radio astronomy – Yebes 8-9 June 2017

Cavity filter tested on liq. N2 T&M of FILTERS Cavity filter tested on liq. N2 INTRODUCTION Why a Filter? HTS FILTRES The Process HTS FILTERS Examples NEXT STEPS CONCLUSIONS HTS C-Band : Cryostat measurement Detection and measurement of RFI on radio astronomy – Yebes 8-9 June 2017

INTRODUCTION Why a Filter? HTS FILTRES The Process T&M of FILTERS INTRODUCTION Why a Filter? HTS FILTRES The Process HTS FILTERS Examples NEXT STEPS CONCLUSIONS HTS C-Band : Noise temperature method Detection and measurement of RFI on radio astronomy – Yebes 8-9 June 2017

INTRODUCTION Why a Filter? HTS FILTRES The Process THE FILTERS INSTALLED P-Band (VHF) HTS Filter On prime focus receiver INTRODUCTION Why a Filter? HTS FILTRES The Process HTS FILTERS Examples NEXT STEPS CONCLUSIONS C-Band (5 GHz) HTS Filter On Gregorian receiver Detection and measurement of RFI on radio astronomy – Yebes 8-9 June 2017

INTRODUCTION Why a Filter? HTS FILTRES The Process THE FILTERS INSTALLED INTRODUCTION Why a Filter? HTS FILTRES The Process HTS FILTERS Examples NEXT STEPS CONCLUSIONS P-Band (305-410 MHz) Detection and measurement of RFI on radio astronomy – Yebes 8-9 June 2017

INTRODUCTION Why a Filter? HTS FILTRES The Process THE FILTERS INSTALLED INTRODUCTION Why a Filter? HTS FILTRES The Process HTS FILTERS Examples NEXT STEPS CONCLUSIONS P-Band (305-410 MHz) Detection and measurement of RFI on radio astronomy – Yebes 8-9 June 2017

INTRODUCTION Why a Filter? HTS FILTRES The Process THE FILTERS BUILD INTRODUCTION Why a Filter? HTS FILTRES The Process HTS FILTERS Examples NEXT STEPS CONCLUSIONS C-Band (7 GHz) HTS Filters Detection and measurement of RFI on radio astronomy – Yebes 8-9 June 2017

INTRODUCTION Why a Filter? HTS FILTRES The Process THE FILTERS BUILD INTRODUCTION Why a Filter? HTS FILTRES The Process HTS FILTERS Examples NEXT STEPS CONCLUSIONS C-Band (7 GHz) HTS Filter Detection and measurement of RFI on radio astronomy – Yebes 8-9 June 2017

INTRODUCTION Why a Filter? HTS FILTRES The Process RECENT JOB INTRODUCTION Why a Filter? HTS FILTRES The Process HTS FILTERS Examples NEXT STEPS CONCLUSIONS C-Band, 4.3…5.8GHz for SRT S-Band, 2.20…2.38 GHz credits: Jose A. Lopez-Perez Pablo García Carreño Yebes Observatory 7 poles + notch 9 poles Detection and measurement of RFI on radio astronomy – Yebes 8-9 June 2017

INTRODUCTION Why a Filter? HTS FILTRES The Process THE FILTERS BUILD INTRODUCTION Why a Filter? HTS FILTRES The Process HTS FILTERS Examples NEXT STEPS CONCLUSIONS Detection and measurement of RFI on radio astronomy – Yebes 8-9 June 2017

INTRODUCTION Why a Filter? HTS FILTRES The Process HTS FILTRERS PRO vs CONS PRO CONS reliability P-band is working on SRT since 3 years only cold It works only if the receiver is cooled non microfonic While the cavity filter can be.  not of the shelf Require in house development and expertise. Is it really a CONS or it is an opportunity to join international collaborations? Small dimension Due to er as high as 9.6. Small dimension means small mass. Non impact on cool down time.  cost a 2” wafer costs 4500€ + 1000€ mechanical and plating + assembly and T&M low loss lowest loss technology known   replicability high INTRODUCTION Why a Filter? HTS FILTRES The Process HTS FILTERS Examples NEXT STEPS CONCLUSIONS Detection and measurement of RFI on radio astronomy – Yebes 8-9 June 2017

INTRODUCTION Why a Filter? HTS FILTRES The Process FOUND PROBLEMS LESSON LEARNED Loss is dominated by connectors body and pin joint. Loss of K connector is higher than SMA connector, But SMA central tab tend to pull and crack the epoxy. Consequently, K connector has been adopted. INTRODUCTION Why a Filter? HTS FILTRES The Process HTS FILTERS Examples NEXT STEPS CONCLUSIONS Ti alloy is hard and difficult to machine, especially threathed holes. But a good mechanical workshop has been found. X The plating of Ti alloy is extremely difficult. Not easy find a galvanic plant. But found For these reasons Ti alloy is a critical issue, we experimented also copper instead but the PCB cracks due to high DCTE Detection and measurement of RFI on radio astronomy – Yebes 8-9 June 2017

INTRODUCTION Why a Filter? HTS FILTRES The Process NEXT STEPS / CONCLUSIONS Reflection coefficient does not match the simulated one. Need to understand why. The loss of the connector body cannot be lowered. But the contact to microstrip can be. Bond-wires / ribbon against epoxy. INTRODUCTION Why a Filter? HTS FILTRES The Process HTS FILTERS Examples NEXT STEPS CONCLUSIONS More challenging solution: Integration of the HTS Filter and LNA in the same house. Reconsider traditional metals as housing. Maybe drawing solutions can compensate the stress More accurate / advanced VNA error correction techniques Sincere (and not rhetoric) thanks to the SOC and the LOC for excellent organization. Thanks to for the partial support to the travel Detection and measurement of RFI on radio astronomy – Yebes 8-9 June 2017