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Journal of Physics: Conference Series OPEN ACCESS A cryogenic front end for CDMA and UMTS wireless base stations To cite this article: H Piel et al 2006 J. Phys.: Conf. Ser. 43 331 View the article online for updates and enhancements. You may also like Mobile phone types and SAR characteristics of the human brain Ae-Kyoung Lee, Seon-Eui Hong, Jong- Hwa Kwon et al. - MAI statistics estimation and analysis in a DS-CDMA system A Alami Hassani, M Zouak, M Mrabti et al. - Outdoor RF spectral study available from cell-phone towers in sub-urban areas for ambient RF energy harvesting Omar M AbdelGhany, Ayman G Sobih and Ayman M El-Tager - Recent citations DC–3 GHz lownoise, flatgainresponse, and highlinearity amplifier YinHua Yao and TongXiu Fan - A. Knack et al - This content was downloaded from IP address 180.246.229.173 on 20/12/2021 at 17:44
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Page 1: A cryogenic front end for CDMA and UMTS wireless base stations

Journal of Physics Conference Series

OPEN ACCESS

A cryogenic front end for CDMA and UMTSwireless base stationsTo cite this article H Piel et al 2006 J Phys Conf Ser 43 331

View the article online for updates and enhancements

You may also likeMobile phone types and SARcharacteristics of the human brainAe-Kyoung Lee Seon-Eui Hong Jong-Hwa Kwon et al

-

MAI statistics estimation and analysis in aDS-CDMA systemA Alami Hassani M Zouak M Mrabti et al

-

Outdoor RF spectral study available fromcell-phone towers in sub-urban areas forambient RF energy harvestingOmar M AbdelGhany Ayman G Sobih andAyman M El-Tager

-

Recent citationsDCndash3 GHz lownoise flatgainresponseand highlinearity amplifierYinHua Yao and TongXiu Fan

-

A Knack et al-

This content was downloaded from IP address 180246229173 on 20122021 at 1744

A cryogenic front end for CDMA and UMTS wireless base stations

H Piel1 B Aminov1 F Aminova1 Cao Bisong2 M Getta1 S Kolesov1 A Knack13 J Mazierska34 N Pupeter1 Wei Bin2 D Wehler1 and Zhang Xiaoping2

1Cryoelectra GmbH Wettinerstr 6H D42287 Wuppertal Germany 2Tsinghua University Beijing PRChina 3James Cook University Townsville Australia 4Massey University New Zealand

Abstract The design and the laboratory performance of a cryogenic front end for CDMA and UMTS wireless base stations is described together with the results of a first field test at a CDMA base station in the region of Tangshan in China The central elements of the cryogenic front ends are the cryocooler the cryostat and the cryogenic platform mounted with up to 6 HTS pre-selection filters of high selectivity combined with the corresponding cryogenic low noise amplifiers of high dynamic range as well as the associated control electronics Design and performance of the UMTS and CDMA filters are described and the characteristic parameters of the cryogenic low noise preamplifier are given An analysis of the results of the first field test is discussed

1 Introduction Early exploratory measurements of the radio frequency (rf) Joule losses in polycrystalline YBCO samples1 and the encouraging experimental results on the rf surface resistance of epitaxially grown YBCO thin films on SrTiO3 substrates23 have indicated the possibility of the application of HTS materials in microwave systems The early availability of high quality commercially produced YBCO coated sapphire wafers4 have nourished this expectation About five years after the discovery of high temperature superconductivity5 planar superconducting microwave bandpass filters appeared to be one of the first and challenging application of HTS technology in the fast growing area of wireless communication HTS bandpass filters combined with cryogenic low noise amplifiers were considered to be attractive as cryogenic front ends for wireless base stations in mobile communication systems all around the world The most successful commercial application of cryogenic front ends has been demonstrated by STI by the installation of about 5000 systems predominantly in the United States in the past years6 In the years after 2002 a collaboration between scientists of Germany the PR of China Australia and New Zealand was established in order to strengthen their contribution to this promising application of high temperature superconductivity to share technologies and to make use of global application opportunities It is the main subject of this collaboration to investigate if high temperature rf-superconductivity proves to be an important technological contribution to future wireless communication This report summarises in short our most recent activities

Institute of Physics Publishing Journal of Physics Conference Series 43 (2006) 1354ndash1357doi1010881742-6596431331 7th European Conference on Applied Superconductivity

1354copy 2006 IOP Publishing Ltd

188 189 190 191 192 193 194 195 196 197 198-80

-60

-40

-20

0

20

f [GHz]

MS2

1 [d

B]

-50

-40

-30

-20

-10

0

MS11 [dB]

2 UMTS and CDMA bandpass filters In the years 1998 to 2003 UMTS bandpass filters were developed at Cryoelectra78 based on a patented design of Heinz Chaloupka9 The central component of this elliptic filter design is a dual mode resonator with two poles and two transmission zeros A filter with N+1 poles and N transmission zeros is composed of N2 dual mode resonators and one H-type resonator which couples the two groups of dual mode resonators to one filter Two characteristics of these filters are shown in figures 1 and 2

Figure 1 17 pole quasi elliptic UMTS filter with 20 MHz bandwidth and a roll off of 80dBMHz

Figure 2 9 pole quasi elliptic UMTS filter with 5 MHz bandwidth and a roll off of 50dBMHz

At Tsinghua University a CDMA bandpass filter was developed10 for a series of field tests of cryogenic front ends in the PR of China The filter has 16 poles and two transmission zeros The frequency dependence of gain noise figure of the CDMA-Filter-LNA-Combination (CDMA-FLNA) is shown in figures 3

805 810 815 820 825 830 835 840 845 850 855

-70

-60

-50

-40

-30

-20

-10

0

10

20

f [MHz]

MS2

1 [d

B]

-50

-45

-40

-35

-30

-25

-20

-15

-10

-5

0

MS11 [dB

]

Figure 3 Characteristic of Tsinghua CDMA-Filter plus LNA (FLNA)

826 828 830 832 834 836 838 84018

19

20

21

22

23

Frequency MHz

Gai

n d

B

04

06

08

10

12

14

Noise Figure dB

Figure 4 Frequency dependence of noise figure (05 dB at centre frequency and gain of the FLNA

3 A low noise amplifier with improved dynamic range High quality low noise preamplifiers are of decisive importance for the quality of a cryogenic front end At Cryoelectra a low noise cryogenic amplifier was developed based on the ATF-54143 transistor for the UMTS band The rf input signal to the amplifier is split by a 3 dB hybrid amplified in two parallel ATF-54143 transistor amplifiers and combined again (for details see ref 8) The IP1 point of this amplifier is 64 dBm (see figure 5) and surpasses the IP3 point of commercial cryogenic amplifiers which are available to us (MITEQ LNA AFS1-01900200-02-CR-2) by 94 dB The LNA used in the filterndashLNA Combination of the Tsinghua cryogenic front end follows the same design as the UMTS-LNA modified for CDMA frequencies The electronic design of the LNA is shown in the photograph of figure 6

1925 1930 1935 1940 1945 1950 1955 1960 1965 1970 1975-80

-60

-40

-20

0

f [GHz]M

S21

[dB

]-40

-30

-20

-10

0

MS

11 [dB]

1355

Figure 5 Dynamic range of the LNA (Linearity of Pout versus Pin)

Figure 6 Equipped PCB of the LNA The two hybrids and the two branches of the LNA are shown

4 Front end support systems Several cryogenic UMTS and CDMA front end support systems have been developed at Cryoelectra and at Tsinghua University A cryogenic front end support system consists primarily of the cryocooler the vacuum tank the vacuum system the cryogenic platform to which the bandpass filter LNA combinations are mounted and the cryogenic rf cables connecting the room temperature rf components with the cryogenic assembly of the FLNAs An electronic control system takes care of the temperature control of the FLNAs delivers the different bias voltages the control of the bypass relays and other electronic features considered necessary to the specific application environment of the cryogenic front end The first Cryoelectra front end used for exploratory UMTS field tests is shown in figure 7 The FLNAs are mounted on a flat cryogenic platform mounted to the cold head of a Leybold cryocooler using a flexible cryogenic coupling The cryogenic stainless steel rf cables with silver plated inner conductors of low rf loss and high thermal resistance are seen together with the 17 pole bandpass filters each of them followed by a MITEQ low noise cryogenic amplifier

Figure 7 View into the vacuum chamber of the Cryoelectra cryogenic front end used in a first UMTS field test

Figure 8 Experimental cryogenic front end used in the Wunongchang field test

1356

5 The Wunongchang field test A first field test was carried out by Tsinghua University in the Wunongchang base station of China Unicom using the cryogenic front end shown in figure 8 The design of this front end is determined by a maximum of convenience for preparatory experiments in the laboratory It can be assembled and disassembled conveniently and its vacuum is supplied by a 2ls ion getter pump Three FLNAs are mounted on a vertical obelisk with an hexagonal cross section mounted to the cold head of a Leybold cooler in vertical position The rf cable connections are similar to the ones shown in the design of figure 7 In the field test two of the three FLNAs are used to pre-select and to pre-amplify the receive signals of one main antenna and the corresponding diversity antenna The pre-amplified signals are then transferred to the commercial base station electronics By a microwave switch the HTS filter LNA combination can be bypassed and the antennas are then connected to the base station electronics in the standard way The prime motivation for the Wunongchang base station field test was to gain experience with all of the related procedures and to demonstrate the reliability of the cryogenic front end under standard operating conditions The cryogenic front end was first operated in the base station in April 2004 The system has been working reliably up to the time that this report is written A drive test was carried out in April of 2004 During this drive test a vehicle equipped with a mobile phone and appropriate equipment was monitoring the transmission power of the mobile phone which in turn was controlled by the Wunongchang base station By switching the bypass this power was registered for the case with and without pre-amplification and pre-selection by the cryogenic front end A significant reduction of the mobile phone power by in the average 3 dB was observed This large reduction came as a surprise to us It was not expected on the basis of a coverage and capacity model11 developed in order to analyse this and similar experiments The reason for this significant improvement has to be investigated in more detail in future experiments For this purpose a new test using 5 base stations equipped with cryogenic front ends for all of the relevant antennas is being prepared by Tsinghua University Acknowledgements This project was funded in part by the German Federal Ministry for Education and Research (BMBF) the German Ministry for Economy and Labour of the State of Nordrhein-Westfalen the Australian Post-Graduate Association and the National Natural Science Foundation of the PR China

[1] Hagen M Hein M Klein N Michalke A Mueller F M Muumlller G Piel H Roumlth Sheinberg H and Smith J-

L 1987 Journal of Magnetism and Magnetic Materials 68 L1-L5 [2] Klein N Muumlller G Piel H Roas B Schultz L Klein U and Peiniger M 1989 Appl Phys Lett 54 757 [3] Klein N Chaloupka H Muumlller G Orbach S Piel H Roas B Schultz L Klein U Peiniger M 1990

JApplPhys 67 6940 [4] Berberich P Utz B Prusseit W Kinder H 1994 Physica C 219 497-504 [5] Bednorz J G and Muumlller K A 1986 Z Phys B 64 189 [6 ] Hammond B Superconductor Technologies Santa Barbara USA 2005 private Communication [7] Kolesov S Aminov B Chaloupka H Draganic Z Kaiser T Kreiskott S Medelius H Piel H Pupeter N

Wagner R and Wehler D 2000 Proc of the Applied Superconductivity Conf in Virginia Beach USA [8] Cryoelectra Report CRE 4-2004 (in German) [9] Chaloupka H 1999 German Patent 199 41 3118-35 Resonatorkonfiguration zur Realisierung von

Hochfrequenz-Bandpassfiltern mit Daumlmpfungspolen [10] Guo X B Cao B S Wei B Zhang X P Yin Z S He W J He S Gao L M Zhu M H Gao B X Aminov B

Getta M Kolesov S Piel H Pupeter N and Wehler D 2004 China Jof Phys 42 463 [11] Knack A Kolesov S and Mazierska submitted to the Asia Pacific Microwave Conference APMC2005

Suzhou China 4-7 December 2005

1357

Page 2: A cryogenic front end for CDMA and UMTS wireless base stations

A cryogenic front end for CDMA and UMTS wireless base stations

H Piel1 B Aminov1 F Aminova1 Cao Bisong2 M Getta1 S Kolesov1 A Knack13 J Mazierska34 N Pupeter1 Wei Bin2 D Wehler1 and Zhang Xiaoping2

1Cryoelectra GmbH Wettinerstr 6H D42287 Wuppertal Germany 2Tsinghua University Beijing PRChina 3James Cook University Townsville Australia 4Massey University New Zealand

Abstract The design and the laboratory performance of a cryogenic front end for CDMA and UMTS wireless base stations is described together with the results of a first field test at a CDMA base station in the region of Tangshan in China The central elements of the cryogenic front ends are the cryocooler the cryostat and the cryogenic platform mounted with up to 6 HTS pre-selection filters of high selectivity combined with the corresponding cryogenic low noise amplifiers of high dynamic range as well as the associated control electronics Design and performance of the UMTS and CDMA filters are described and the characteristic parameters of the cryogenic low noise preamplifier are given An analysis of the results of the first field test is discussed

1 Introduction Early exploratory measurements of the radio frequency (rf) Joule losses in polycrystalline YBCO samples1 and the encouraging experimental results on the rf surface resistance of epitaxially grown YBCO thin films on SrTiO3 substrates23 have indicated the possibility of the application of HTS materials in microwave systems The early availability of high quality commercially produced YBCO coated sapphire wafers4 have nourished this expectation About five years after the discovery of high temperature superconductivity5 planar superconducting microwave bandpass filters appeared to be one of the first and challenging application of HTS technology in the fast growing area of wireless communication HTS bandpass filters combined with cryogenic low noise amplifiers were considered to be attractive as cryogenic front ends for wireless base stations in mobile communication systems all around the world The most successful commercial application of cryogenic front ends has been demonstrated by STI by the installation of about 5000 systems predominantly in the United States in the past years6 In the years after 2002 a collaboration between scientists of Germany the PR of China Australia and New Zealand was established in order to strengthen their contribution to this promising application of high temperature superconductivity to share technologies and to make use of global application opportunities It is the main subject of this collaboration to investigate if high temperature rf-superconductivity proves to be an important technological contribution to future wireless communication This report summarises in short our most recent activities

Institute of Physics Publishing Journal of Physics Conference Series 43 (2006) 1354ndash1357doi1010881742-6596431331 7th European Conference on Applied Superconductivity

1354copy 2006 IOP Publishing Ltd

188 189 190 191 192 193 194 195 196 197 198-80

-60

-40

-20

0

20

f [GHz]

MS2

1 [d

B]

-50

-40

-30

-20

-10

0

MS11 [dB]

2 UMTS and CDMA bandpass filters In the years 1998 to 2003 UMTS bandpass filters were developed at Cryoelectra78 based on a patented design of Heinz Chaloupka9 The central component of this elliptic filter design is a dual mode resonator with two poles and two transmission zeros A filter with N+1 poles and N transmission zeros is composed of N2 dual mode resonators and one H-type resonator which couples the two groups of dual mode resonators to one filter Two characteristics of these filters are shown in figures 1 and 2

Figure 1 17 pole quasi elliptic UMTS filter with 20 MHz bandwidth and a roll off of 80dBMHz

Figure 2 9 pole quasi elliptic UMTS filter with 5 MHz bandwidth and a roll off of 50dBMHz

At Tsinghua University a CDMA bandpass filter was developed10 for a series of field tests of cryogenic front ends in the PR of China The filter has 16 poles and two transmission zeros The frequency dependence of gain noise figure of the CDMA-Filter-LNA-Combination (CDMA-FLNA) is shown in figures 3

805 810 815 820 825 830 835 840 845 850 855

-70

-60

-50

-40

-30

-20

-10

0

10

20

f [MHz]

MS2

1 [d

B]

-50

-45

-40

-35

-30

-25

-20

-15

-10

-5

0

MS11 [dB

]

Figure 3 Characteristic of Tsinghua CDMA-Filter plus LNA (FLNA)

826 828 830 832 834 836 838 84018

19

20

21

22

23

Frequency MHz

Gai

n d

B

04

06

08

10

12

14

Noise Figure dB

Figure 4 Frequency dependence of noise figure (05 dB at centre frequency and gain of the FLNA

3 A low noise amplifier with improved dynamic range High quality low noise preamplifiers are of decisive importance for the quality of a cryogenic front end At Cryoelectra a low noise cryogenic amplifier was developed based on the ATF-54143 transistor for the UMTS band The rf input signal to the amplifier is split by a 3 dB hybrid amplified in two parallel ATF-54143 transistor amplifiers and combined again (for details see ref 8) The IP1 point of this amplifier is 64 dBm (see figure 5) and surpasses the IP3 point of commercial cryogenic amplifiers which are available to us (MITEQ LNA AFS1-01900200-02-CR-2) by 94 dB The LNA used in the filterndashLNA Combination of the Tsinghua cryogenic front end follows the same design as the UMTS-LNA modified for CDMA frequencies The electronic design of the LNA is shown in the photograph of figure 6

1925 1930 1935 1940 1945 1950 1955 1960 1965 1970 1975-80

-60

-40

-20

0

f [GHz]M

S21

[dB

]-40

-30

-20

-10

0

MS

11 [dB]

1355

Figure 5 Dynamic range of the LNA (Linearity of Pout versus Pin)

Figure 6 Equipped PCB of the LNA The two hybrids and the two branches of the LNA are shown

4 Front end support systems Several cryogenic UMTS and CDMA front end support systems have been developed at Cryoelectra and at Tsinghua University A cryogenic front end support system consists primarily of the cryocooler the vacuum tank the vacuum system the cryogenic platform to which the bandpass filter LNA combinations are mounted and the cryogenic rf cables connecting the room temperature rf components with the cryogenic assembly of the FLNAs An electronic control system takes care of the temperature control of the FLNAs delivers the different bias voltages the control of the bypass relays and other electronic features considered necessary to the specific application environment of the cryogenic front end The first Cryoelectra front end used for exploratory UMTS field tests is shown in figure 7 The FLNAs are mounted on a flat cryogenic platform mounted to the cold head of a Leybold cryocooler using a flexible cryogenic coupling The cryogenic stainless steel rf cables with silver plated inner conductors of low rf loss and high thermal resistance are seen together with the 17 pole bandpass filters each of them followed by a MITEQ low noise cryogenic amplifier

Figure 7 View into the vacuum chamber of the Cryoelectra cryogenic front end used in a first UMTS field test

Figure 8 Experimental cryogenic front end used in the Wunongchang field test

1356

5 The Wunongchang field test A first field test was carried out by Tsinghua University in the Wunongchang base station of China Unicom using the cryogenic front end shown in figure 8 The design of this front end is determined by a maximum of convenience for preparatory experiments in the laboratory It can be assembled and disassembled conveniently and its vacuum is supplied by a 2ls ion getter pump Three FLNAs are mounted on a vertical obelisk with an hexagonal cross section mounted to the cold head of a Leybold cooler in vertical position The rf cable connections are similar to the ones shown in the design of figure 7 In the field test two of the three FLNAs are used to pre-select and to pre-amplify the receive signals of one main antenna and the corresponding diversity antenna The pre-amplified signals are then transferred to the commercial base station electronics By a microwave switch the HTS filter LNA combination can be bypassed and the antennas are then connected to the base station electronics in the standard way The prime motivation for the Wunongchang base station field test was to gain experience with all of the related procedures and to demonstrate the reliability of the cryogenic front end under standard operating conditions The cryogenic front end was first operated in the base station in April 2004 The system has been working reliably up to the time that this report is written A drive test was carried out in April of 2004 During this drive test a vehicle equipped with a mobile phone and appropriate equipment was monitoring the transmission power of the mobile phone which in turn was controlled by the Wunongchang base station By switching the bypass this power was registered for the case with and without pre-amplification and pre-selection by the cryogenic front end A significant reduction of the mobile phone power by in the average 3 dB was observed This large reduction came as a surprise to us It was not expected on the basis of a coverage and capacity model11 developed in order to analyse this and similar experiments The reason for this significant improvement has to be investigated in more detail in future experiments For this purpose a new test using 5 base stations equipped with cryogenic front ends for all of the relevant antennas is being prepared by Tsinghua University Acknowledgements This project was funded in part by the German Federal Ministry for Education and Research (BMBF) the German Ministry for Economy and Labour of the State of Nordrhein-Westfalen the Australian Post-Graduate Association and the National Natural Science Foundation of the PR China

[1] Hagen M Hein M Klein N Michalke A Mueller F M Muumlller G Piel H Roumlth Sheinberg H and Smith J-

L 1987 Journal of Magnetism and Magnetic Materials 68 L1-L5 [2] Klein N Muumlller G Piel H Roas B Schultz L Klein U and Peiniger M 1989 Appl Phys Lett 54 757 [3] Klein N Chaloupka H Muumlller G Orbach S Piel H Roas B Schultz L Klein U Peiniger M 1990

JApplPhys 67 6940 [4] Berberich P Utz B Prusseit W Kinder H 1994 Physica C 219 497-504 [5] Bednorz J G and Muumlller K A 1986 Z Phys B 64 189 [6 ] Hammond B Superconductor Technologies Santa Barbara USA 2005 private Communication [7] Kolesov S Aminov B Chaloupka H Draganic Z Kaiser T Kreiskott S Medelius H Piel H Pupeter N

Wagner R and Wehler D 2000 Proc of the Applied Superconductivity Conf in Virginia Beach USA [8] Cryoelectra Report CRE 4-2004 (in German) [9] Chaloupka H 1999 German Patent 199 41 3118-35 Resonatorkonfiguration zur Realisierung von

Hochfrequenz-Bandpassfiltern mit Daumlmpfungspolen [10] Guo X B Cao B S Wei B Zhang X P Yin Z S He W J He S Gao L M Zhu M H Gao B X Aminov B

Getta M Kolesov S Piel H Pupeter N and Wehler D 2004 China Jof Phys 42 463 [11] Knack A Kolesov S and Mazierska submitted to the Asia Pacific Microwave Conference APMC2005

Suzhou China 4-7 December 2005

1357

Page 3: A cryogenic front end for CDMA and UMTS wireless base stations

188 189 190 191 192 193 194 195 196 197 198-80

-60

-40

-20

0

20

f [GHz]

MS2

1 [d

B]

-50

-40

-30

-20

-10

0

MS11 [dB]

2 UMTS and CDMA bandpass filters In the years 1998 to 2003 UMTS bandpass filters were developed at Cryoelectra78 based on a patented design of Heinz Chaloupka9 The central component of this elliptic filter design is a dual mode resonator with two poles and two transmission zeros A filter with N+1 poles and N transmission zeros is composed of N2 dual mode resonators and one H-type resonator which couples the two groups of dual mode resonators to one filter Two characteristics of these filters are shown in figures 1 and 2

Figure 1 17 pole quasi elliptic UMTS filter with 20 MHz bandwidth and a roll off of 80dBMHz

Figure 2 9 pole quasi elliptic UMTS filter with 5 MHz bandwidth and a roll off of 50dBMHz

At Tsinghua University a CDMA bandpass filter was developed10 for a series of field tests of cryogenic front ends in the PR of China The filter has 16 poles and two transmission zeros The frequency dependence of gain noise figure of the CDMA-Filter-LNA-Combination (CDMA-FLNA) is shown in figures 3

805 810 815 820 825 830 835 840 845 850 855

-70

-60

-50

-40

-30

-20

-10

0

10

20

f [MHz]

MS2

1 [d

B]

-50

-45

-40

-35

-30

-25

-20

-15

-10

-5

0

MS11 [dB

]

Figure 3 Characteristic of Tsinghua CDMA-Filter plus LNA (FLNA)

826 828 830 832 834 836 838 84018

19

20

21

22

23

Frequency MHz

Gai

n d

B

04

06

08

10

12

14

Noise Figure dB

Figure 4 Frequency dependence of noise figure (05 dB at centre frequency and gain of the FLNA

3 A low noise amplifier with improved dynamic range High quality low noise preamplifiers are of decisive importance for the quality of a cryogenic front end At Cryoelectra a low noise cryogenic amplifier was developed based on the ATF-54143 transistor for the UMTS band The rf input signal to the amplifier is split by a 3 dB hybrid amplified in two parallel ATF-54143 transistor amplifiers and combined again (for details see ref 8) The IP1 point of this amplifier is 64 dBm (see figure 5) and surpasses the IP3 point of commercial cryogenic amplifiers which are available to us (MITEQ LNA AFS1-01900200-02-CR-2) by 94 dB The LNA used in the filterndashLNA Combination of the Tsinghua cryogenic front end follows the same design as the UMTS-LNA modified for CDMA frequencies The electronic design of the LNA is shown in the photograph of figure 6

1925 1930 1935 1940 1945 1950 1955 1960 1965 1970 1975-80

-60

-40

-20

0

f [GHz]M

S21

[dB

]-40

-30

-20

-10

0

MS

11 [dB]

1355

Figure 5 Dynamic range of the LNA (Linearity of Pout versus Pin)

Figure 6 Equipped PCB of the LNA The two hybrids and the two branches of the LNA are shown

4 Front end support systems Several cryogenic UMTS and CDMA front end support systems have been developed at Cryoelectra and at Tsinghua University A cryogenic front end support system consists primarily of the cryocooler the vacuum tank the vacuum system the cryogenic platform to which the bandpass filter LNA combinations are mounted and the cryogenic rf cables connecting the room temperature rf components with the cryogenic assembly of the FLNAs An electronic control system takes care of the temperature control of the FLNAs delivers the different bias voltages the control of the bypass relays and other electronic features considered necessary to the specific application environment of the cryogenic front end The first Cryoelectra front end used for exploratory UMTS field tests is shown in figure 7 The FLNAs are mounted on a flat cryogenic platform mounted to the cold head of a Leybold cryocooler using a flexible cryogenic coupling The cryogenic stainless steel rf cables with silver plated inner conductors of low rf loss and high thermal resistance are seen together with the 17 pole bandpass filters each of them followed by a MITEQ low noise cryogenic amplifier

Figure 7 View into the vacuum chamber of the Cryoelectra cryogenic front end used in a first UMTS field test

Figure 8 Experimental cryogenic front end used in the Wunongchang field test

1356

5 The Wunongchang field test A first field test was carried out by Tsinghua University in the Wunongchang base station of China Unicom using the cryogenic front end shown in figure 8 The design of this front end is determined by a maximum of convenience for preparatory experiments in the laboratory It can be assembled and disassembled conveniently and its vacuum is supplied by a 2ls ion getter pump Three FLNAs are mounted on a vertical obelisk with an hexagonal cross section mounted to the cold head of a Leybold cooler in vertical position The rf cable connections are similar to the ones shown in the design of figure 7 In the field test two of the three FLNAs are used to pre-select and to pre-amplify the receive signals of one main antenna and the corresponding diversity antenna The pre-amplified signals are then transferred to the commercial base station electronics By a microwave switch the HTS filter LNA combination can be bypassed and the antennas are then connected to the base station electronics in the standard way The prime motivation for the Wunongchang base station field test was to gain experience with all of the related procedures and to demonstrate the reliability of the cryogenic front end under standard operating conditions The cryogenic front end was first operated in the base station in April 2004 The system has been working reliably up to the time that this report is written A drive test was carried out in April of 2004 During this drive test a vehicle equipped with a mobile phone and appropriate equipment was monitoring the transmission power of the mobile phone which in turn was controlled by the Wunongchang base station By switching the bypass this power was registered for the case with and without pre-amplification and pre-selection by the cryogenic front end A significant reduction of the mobile phone power by in the average 3 dB was observed This large reduction came as a surprise to us It was not expected on the basis of a coverage and capacity model11 developed in order to analyse this and similar experiments The reason for this significant improvement has to be investigated in more detail in future experiments For this purpose a new test using 5 base stations equipped with cryogenic front ends for all of the relevant antennas is being prepared by Tsinghua University Acknowledgements This project was funded in part by the German Federal Ministry for Education and Research (BMBF) the German Ministry for Economy and Labour of the State of Nordrhein-Westfalen the Australian Post-Graduate Association and the National Natural Science Foundation of the PR China

[1] Hagen M Hein M Klein N Michalke A Mueller F M Muumlller G Piel H Roumlth Sheinberg H and Smith J-

L 1987 Journal of Magnetism and Magnetic Materials 68 L1-L5 [2] Klein N Muumlller G Piel H Roas B Schultz L Klein U and Peiniger M 1989 Appl Phys Lett 54 757 [3] Klein N Chaloupka H Muumlller G Orbach S Piel H Roas B Schultz L Klein U Peiniger M 1990

JApplPhys 67 6940 [4] Berberich P Utz B Prusseit W Kinder H 1994 Physica C 219 497-504 [5] Bednorz J G and Muumlller K A 1986 Z Phys B 64 189 [6 ] Hammond B Superconductor Technologies Santa Barbara USA 2005 private Communication [7] Kolesov S Aminov B Chaloupka H Draganic Z Kaiser T Kreiskott S Medelius H Piel H Pupeter N

Wagner R and Wehler D 2000 Proc of the Applied Superconductivity Conf in Virginia Beach USA [8] Cryoelectra Report CRE 4-2004 (in German) [9] Chaloupka H 1999 German Patent 199 41 3118-35 Resonatorkonfiguration zur Realisierung von

Hochfrequenz-Bandpassfiltern mit Daumlmpfungspolen [10] Guo X B Cao B S Wei B Zhang X P Yin Z S He W J He S Gao L M Zhu M H Gao B X Aminov B

Getta M Kolesov S Piel H Pupeter N and Wehler D 2004 China Jof Phys 42 463 [11] Knack A Kolesov S and Mazierska submitted to the Asia Pacific Microwave Conference APMC2005

Suzhou China 4-7 December 2005

1357

Page 4: A cryogenic front end for CDMA and UMTS wireless base stations

Figure 5 Dynamic range of the LNA (Linearity of Pout versus Pin)

Figure 6 Equipped PCB of the LNA The two hybrids and the two branches of the LNA are shown

4 Front end support systems Several cryogenic UMTS and CDMA front end support systems have been developed at Cryoelectra and at Tsinghua University A cryogenic front end support system consists primarily of the cryocooler the vacuum tank the vacuum system the cryogenic platform to which the bandpass filter LNA combinations are mounted and the cryogenic rf cables connecting the room temperature rf components with the cryogenic assembly of the FLNAs An electronic control system takes care of the temperature control of the FLNAs delivers the different bias voltages the control of the bypass relays and other electronic features considered necessary to the specific application environment of the cryogenic front end The first Cryoelectra front end used for exploratory UMTS field tests is shown in figure 7 The FLNAs are mounted on a flat cryogenic platform mounted to the cold head of a Leybold cryocooler using a flexible cryogenic coupling The cryogenic stainless steel rf cables with silver plated inner conductors of low rf loss and high thermal resistance are seen together with the 17 pole bandpass filters each of them followed by a MITEQ low noise cryogenic amplifier

Figure 7 View into the vacuum chamber of the Cryoelectra cryogenic front end used in a first UMTS field test

Figure 8 Experimental cryogenic front end used in the Wunongchang field test

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5 The Wunongchang field test A first field test was carried out by Tsinghua University in the Wunongchang base station of China Unicom using the cryogenic front end shown in figure 8 The design of this front end is determined by a maximum of convenience for preparatory experiments in the laboratory It can be assembled and disassembled conveniently and its vacuum is supplied by a 2ls ion getter pump Three FLNAs are mounted on a vertical obelisk with an hexagonal cross section mounted to the cold head of a Leybold cooler in vertical position The rf cable connections are similar to the ones shown in the design of figure 7 In the field test two of the three FLNAs are used to pre-select and to pre-amplify the receive signals of one main antenna and the corresponding diversity antenna The pre-amplified signals are then transferred to the commercial base station electronics By a microwave switch the HTS filter LNA combination can be bypassed and the antennas are then connected to the base station electronics in the standard way The prime motivation for the Wunongchang base station field test was to gain experience with all of the related procedures and to demonstrate the reliability of the cryogenic front end under standard operating conditions The cryogenic front end was first operated in the base station in April 2004 The system has been working reliably up to the time that this report is written A drive test was carried out in April of 2004 During this drive test a vehicle equipped with a mobile phone and appropriate equipment was monitoring the transmission power of the mobile phone which in turn was controlled by the Wunongchang base station By switching the bypass this power was registered for the case with and without pre-amplification and pre-selection by the cryogenic front end A significant reduction of the mobile phone power by in the average 3 dB was observed This large reduction came as a surprise to us It was not expected on the basis of a coverage and capacity model11 developed in order to analyse this and similar experiments The reason for this significant improvement has to be investigated in more detail in future experiments For this purpose a new test using 5 base stations equipped with cryogenic front ends for all of the relevant antennas is being prepared by Tsinghua University Acknowledgements This project was funded in part by the German Federal Ministry for Education and Research (BMBF) the German Ministry for Economy and Labour of the State of Nordrhein-Westfalen the Australian Post-Graduate Association and the National Natural Science Foundation of the PR China

[1] Hagen M Hein M Klein N Michalke A Mueller F M Muumlller G Piel H Roumlth Sheinberg H and Smith J-

L 1987 Journal of Magnetism and Magnetic Materials 68 L1-L5 [2] Klein N Muumlller G Piel H Roas B Schultz L Klein U and Peiniger M 1989 Appl Phys Lett 54 757 [3] Klein N Chaloupka H Muumlller G Orbach S Piel H Roas B Schultz L Klein U Peiniger M 1990

JApplPhys 67 6940 [4] Berberich P Utz B Prusseit W Kinder H 1994 Physica C 219 497-504 [5] Bednorz J G and Muumlller K A 1986 Z Phys B 64 189 [6 ] Hammond B Superconductor Technologies Santa Barbara USA 2005 private Communication [7] Kolesov S Aminov B Chaloupka H Draganic Z Kaiser T Kreiskott S Medelius H Piel H Pupeter N

Wagner R and Wehler D 2000 Proc of the Applied Superconductivity Conf in Virginia Beach USA [8] Cryoelectra Report CRE 4-2004 (in German) [9] Chaloupka H 1999 German Patent 199 41 3118-35 Resonatorkonfiguration zur Realisierung von

Hochfrequenz-Bandpassfiltern mit Daumlmpfungspolen [10] Guo X B Cao B S Wei B Zhang X P Yin Z S He W J He S Gao L M Zhu M H Gao B X Aminov B

Getta M Kolesov S Piel H Pupeter N and Wehler D 2004 China Jof Phys 42 463 [11] Knack A Kolesov S and Mazierska submitted to the Asia Pacific Microwave Conference APMC2005

Suzhou China 4-7 December 2005

1357

Page 5: A cryogenic front end for CDMA and UMTS wireless base stations

5 The Wunongchang field test A first field test was carried out by Tsinghua University in the Wunongchang base station of China Unicom using the cryogenic front end shown in figure 8 The design of this front end is determined by a maximum of convenience for preparatory experiments in the laboratory It can be assembled and disassembled conveniently and its vacuum is supplied by a 2ls ion getter pump Three FLNAs are mounted on a vertical obelisk with an hexagonal cross section mounted to the cold head of a Leybold cooler in vertical position The rf cable connections are similar to the ones shown in the design of figure 7 In the field test two of the three FLNAs are used to pre-select and to pre-amplify the receive signals of one main antenna and the corresponding diversity antenna The pre-amplified signals are then transferred to the commercial base station electronics By a microwave switch the HTS filter LNA combination can be bypassed and the antennas are then connected to the base station electronics in the standard way The prime motivation for the Wunongchang base station field test was to gain experience with all of the related procedures and to demonstrate the reliability of the cryogenic front end under standard operating conditions The cryogenic front end was first operated in the base station in April 2004 The system has been working reliably up to the time that this report is written A drive test was carried out in April of 2004 During this drive test a vehicle equipped with a mobile phone and appropriate equipment was monitoring the transmission power of the mobile phone which in turn was controlled by the Wunongchang base station By switching the bypass this power was registered for the case with and without pre-amplification and pre-selection by the cryogenic front end A significant reduction of the mobile phone power by in the average 3 dB was observed This large reduction came as a surprise to us It was not expected on the basis of a coverage and capacity model11 developed in order to analyse this and similar experiments The reason for this significant improvement has to be investigated in more detail in future experiments For this purpose a new test using 5 base stations equipped with cryogenic front ends for all of the relevant antennas is being prepared by Tsinghua University Acknowledgements This project was funded in part by the German Federal Ministry for Education and Research (BMBF) the German Ministry for Economy and Labour of the State of Nordrhein-Westfalen the Australian Post-Graduate Association and the National Natural Science Foundation of the PR China

[1] Hagen M Hein M Klein N Michalke A Mueller F M Muumlller G Piel H Roumlth Sheinberg H and Smith J-

L 1987 Journal of Magnetism and Magnetic Materials 68 L1-L5 [2] Klein N Muumlller G Piel H Roas B Schultz L Klein U and Peiniger M 1989 Appl Phys Lett 54 757 [3] Klein N Chaloupka H Muumlller G Orbach S Piel H Roas B Schultz L Klein U Peiniger M 1990

JApplPhys 67 6940 [4] Berberich P Utz B Prusseit W Kinder H 1994 Physica C 219 497-504 [5] Bednorz J G and Muumlller K A 1986 Z Phys B 64 189 [6 ] Hammond B Superconductor Technologies Santa Barbara USA 2005 private Communication [7] Kolesov S Aminov B Chaloupka H Draganic Z Kaiser T Kreiskott S Medelius H Piel H Pupeter N

Wagner R and Wehler D 2000 Proc of the Applied Superconductivity Conf in Virginia Beach USA [8] Cryoelectra Report CRE 4-2004 (in German) [9] Chaloupka H 1999 German Patent 199 41 3118-35 Resonatorkonfiguration zur Realisierung von

Hochfrequenz-Bandpassfiltern mit Daumlmpfungspolen [10] Guo X B Cao B S Wei B Zhang X P Yin Z S He W J He S Gao L M Zhu M H Gao B X Aminov B

Getta M Kolesov S Piel H Pupeter N and Wehler D 2004 China Jof Phys 42 463 [11] Knack A Kolesov S and Mazierska submitted to the Asia Pacific Microwave Conference APMC2005

Suzhou China 4-7 December 2005

1357


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