High Temperature Superconductor Filters for Sardinia Radio Telescope

High Temperature Superconductor Filters for Sardinia Radio Telescope INTRODUCTION Why a Filter? P. Bolli 1, L. Cresci 1, F. Huang 2, S. Mariotti 3 HTS FILTRES The Process HTS FILTERS Examples NEXT STEPS CONCLUSIONS 1 INAF-Osservatorio Astrofisico di Arcetri – Firenze - ITALY 2 School of EECE, University of Birmingham, Edgbaston, Birmingham UK 3 INAF-Istituto di Radioastronomia – Bologna ITALY Detection and measurement of RFI on radio astronomy – Yebes 8 -9 June 2017 D. Panella 1

WHY A FILTER ? INTRODUCTION Why a Filter? HTS FILTRES The Process HTS FILTERS Examples NEXT STEPS CONCLUSIONS 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 d. B, the increase of Tsys is negligible. 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

WHY A FILTER ? § The new frontier of RA calls for large bandwidth (1 octave) 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 Po 1 ~+5 d. Bm. An emerging brand sells excellent LNA but with Po 1 ~ -12 d. Bm (Cband) § 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

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 This mean the loss and the mismatch of the filter should be the lower as possible and Tsys still remain competitive. |s 21| and |s 12| : the lowest possible |s 11| and |s 22| : the lowest possible NEXT STEPS CONCLUSIONS Detection and measurement of RFI on radio astronomy – Yebes 8 -9 June 2017

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? Even more, with wide band, we expect an extremely low loss. HTS FILTRES The Process HTS FILTERS Examples NEXT STEPS CONCLUSIONS LF (intedigital, 20 K) ≈ 0. 4 @ P Band LF (HTS, 20 K) ≈ 0. 04 @ P Band (due to Mg. O substrate – estimated value) Filter Loss [ d. B ] Tsys w/o filter [K] Tsys with filter [K] 0. 05 0. 10 0. 15 0. 20 0. 25 5 5 5. 3 5. 6 5. 9 6. 2 6. 5 15 15 15. 4 15. 8 16. 2 16. 6 17. 1 Detection and measurement of RFI on radio astronomy – Yebes 8 -9 June 2017

THE FILTER HTS furnisher Filter Design 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

HST STRUCTURE Ion Beam Milling GOLD 0. 2 mm HTS (YBCO) 0. 6 mm INTRODUCTION Why a Filter? HTS FILTRES The Process Mg. O Dielectric 500 mm HTS (YBCO) 0. 6 mm GOLD 0. 2 mm HTS FILTERS Examples NEXT STEPS CONCLUSIONS Detection and measurement of RFI on radio astronomy – Yebes 8 -9 June 2017

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

HST DESIGN INTRODUCTION Why a Filter? HTS FILTRES The Process HTS FILTERS Examples NEXT STEPS CONCLUSIONS 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 Ti 6 Al 4 V is the alloy that match the CTE of Mg. O, both at room temperature and in cryogenic environment. In order to better match the CTE, a “gummous” epoxy is used. The Henkek Ablefilm 5025 E – 4 mils is an electrical conductive, gommous, double-sided adhesive tape. Detection and measurement of RFI on radio astronomy – Yebes 8 -9 June 2017

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

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

T&M of FILTERS Cavity filter tested on liq. N 2 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

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

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

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

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

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

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

RECENT JOB INTRODUCTION Why a Filter? HTS FILTRES The Process C-Band, 4. 3… 5. 8 GHz for SRT HTS FILTERS Examples NEXT STEPS CONCLUSIONS S-Band, 2. 20… 2. 38 GHz credits: Jose A. Lopez-Perez Pablo García Carreño Yebes Observatory 7 poles + notch Detection and measurement of RFI on radio astronomy – Yebes 8 -9 June 2017 9 poles

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

HTS FILTRERS PRO vs CONS PRO reliability INTRODUCTION Why a Filter? HTS FILTRES The Process P-band is working on SRT since 3 years only cold It works only if the receiver is cooled not of the shelf Require in house development and expertise. Is it really a CONS or it is an opportunity to join international collaborations? non microfonic While the cavity filter can be. 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 HTS FILTERS Examples NEXT STEPS CONCLUSIONS Detection and measurement of RFI on radio astronomy – Yebes 8 -9 June 2017

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 Ti alloy is hard and difficult to machine, especially threathed holes. But a good mechanical workshop has been found. The plating of Ti alloy is extremely difficult. Not easy find a galvanic plant. But found CONCLUSIONS X 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

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