High‐performance cryogenic fractal 180° hybrid power divider with integrated directional coupler

A 180° hybrid and a directional coupler to be employed in the P-band cryogenic receiver of the Sardinia Radio Telescope are proposed in this work. An in-depth study of the issues related to the use of microwave components for cryogenic radio astronomy receivers is carried out to select the best suited technology and configuration. As a result, a planar fractal 180° hybrid configuration available in the literature has been optimized aiming to increase the operating bandwidth in order to comply with the design specifications of the application at hand. A coupled lines directional coupler with weak coupling and high isolation, used to calibrate the receiver chain, is cascaded to the 180° hybrid and realized in the same layout. The final device, consisting of the 180° hybrid and the directional coupler, has been manufactured and tested at the cryogenic temperature of 20 K, showing a good agreement between experimental results and predicted performance.

[1]  Kimberley W. Eccleston,et al.  Compact planar microstripline branch-line and rat-race couplers , 2003 .

[2]  R. Fano.  Theoretical limitations on the broadband matching of arbitrary impedances , 1950 .

[3]  T. Itoh,et al.  A compact enhanced-bandwidth hybrid ring using an artificial lumped-element left-handed transmission-line section , 2004, IEEE Transactions on Microwave Theory and Techniques.

[4]  Stefan Simion,et al.  Broadband and small-size 3-DB ring coupler , 2014 .

[5]  Kawthar A. Zaki,et al.  Full-wave modeling of generalized double ridge waveguide T-Junctions , 1996 .

[6]  V. Napijalo.  Coupled Line 180$^{\circ}$ Hybrids With Lange Couplers , 2012, IEEE Transactions on Microwave Theory and Techniques.

[7]  Giorgio Montisci,et al.  A Compact L-Band Orthomode Transducer for Radio Astronomical Receivers at Cryogenic Temperature , 2015, IEEE Transactions on Microwave Theory and Techniques.

[8]  Giorgio Montisci,et al.  High-performance microstrip directional coupler for radio-astronomical receivers at cryogenic temperature , 2014 .

[9]  Ning Yang,et al.  Broadband Compact 180 $^{\circ}$ Hybrid Derived From the Wilkinson Divider , 2010, IEEE Transactions on Microwave Theory and Techniques.

[10]  A. Melis,et al.  Sardinia Radio Telescope: General Description, Technical Commissioning and First Light , 2015, 1603.06134.

[11]  Quan Xue,et al.  A Broadband Compact Microstrip Rat-Race Hybrid Using a Novel CPW Inverter , 2007, IEEE Transactions on Microwave Theory and Techniques.

[12]  H. Ghali,et al.  Miniaturized fractal rat-race, branch-line, and coupled-line hybrids , 2004, IEEE Transactions on Microwave Theory and Techniques.

[13]  M. Dydyk,et al.  Microstrip directional couplers with ideal performance via single-element compensation , 1999 .

[14]  Jong-Sik Lim,et al.  A design of single and multi-section microstrip directional coupler with the high directivity , 2004, 2004 IEEE MTT-S International Microwave Symposium Digest (IEEE Cat. No.04CH37535).

[15]  R. M. Foster,et al.  A reactance theorem , 1924 .

[16]  Zhongbao Wang,et al.  Novel Coupled Line 180 $^{\circ}$ Hybrid With Non-Interspersed Input and Output Ports , 2014, IEEE Transactions on Microwave Theory and Techniques.

[17]  V.K. Tripathi,et al.  Compact folded line rat-race hybrid couplers , 2000, IEEE Microwave and Guided Wave Letters.

[18]  Ming-Lin Chuang.  Miniaturized ring coupler of arbitrary reduced size , 2005 .

[19]  G. Nedlin.  Energy in lossless and low-loss networks, and Foster's reactance theorem , 1989 .