LgadCables

Table of Cables

• For a single Board setup one would require the following material:
  
  

  Type	Qt.
  SMA - BNC Cable	3
  BNC - Banana connector	2
  SMA male - SMA male connector	1

Cable Specifications

For cables there are two available options, buying a prefabricated cable with the appropriate connectors at each end or making a cable from scratch. In the latter case, specifications are provided hereafter as to which type of cable is recommended. In any case, a thin broadband coaxial cable should be used, with cooper shield and silver coated cooper core. The RG-174 and RG-316 standards are suitable for this application, with the latter providing a lower attenuation but also weaker poer tolerance.

• Cable only recommendations: A thin, broadband, flexible coaxial cable is recommended incorporating a cooper insulation and core with a 50Ohm impedance. Maximum recommended voltage rating should be at least 3000V. A convenient solution is the HYTEM HY402FLEX broadband cable, supporting up to 20GHz signal frequency with an external diameter of 3.58 mm. Main specifications are available in the following table:
  
  

  Electrical characteristics
  Impedance	50 Ohm
  Cut-off frequency	20 GHz
  Capacitance	95 pF/m
  Propagation Velocity	70 %
  Shielding Effectiveness	100 dB/m
  Time Delay	4.8 ns/m
  Maximum working Voltage	3000 V

  
  The recommended length should be limited to 1.5 m to avoid excessive losses and signal distortion while allowing enough length for connections.
  Detailed specifications are available in the corresponding datasheet: hytem_cable.pdf
  
  
• Pre-fabricated assemblies: It is recommended to use 1.5m long RG-174/RG-316 assemblies with pre-attached male SMA connector at one side and male BNC connector at the other. Two readily available solutions are the Amphenol RF Division 245101-07 and the Cinch Connectivity Solutions Johnson 415-0028 corresponding tot he RG-174 and RG-316 standards respectively. Both are readily available for order form DigiKey:
  
  
  1. Amphenol RF Division 245101-07
  2. Cinch Connectivity Solutions Johnson 415-0028

Connectors Specifications

In case the choice is made to make in-house cables in stead of buying prefabricated solutions, suggestions for the connectors are provided hereafter. It is highly recommended to use a prefabricated option, especially for the RG-316 standard, in order to ensure that all specifications are respected.

• 50Ohm SMA straight plug_ connector: A straight RF SMA male crimp plug connector, compatible with RG-188, RG-316, RG-174, RG-179B, RG-187A cable standards. A 50Ohm impedance with PTFE insulation and a minimum of 12 GHz bandwidth is recommended. A gold plated brass body is preferable with respect to the gold plated stainless steel option, since the latter has a typical of 100 mating cycle in contrast with the 500 cycles of the first type. Electrical and mechanical characteristics of the part are detailed in the following table:
  
  

  Mechanical and electrical specifications
  Working Voltage	500 V
  Proof Voltage	1500 V
  Frequency Range	up to 12.4 GHz
  Impedance	50 Ohm
  Mating Cycles	500
  Cable type	LMR-100, M17/119-RG174, RG-174, RG-188, RG-188A, RG-316
  Termination style	Cable - Crimp
  Orientation	Straight
  Body material	Gold plated Brass
  Insulator	PTFE

  
  A suitable part is provided by Amphenol (no. 132114) and is available for order at Digikey (ACX1202-ND). The corresponding datasheet and relevant information are available here.

• 50Ohm BNC straight plug connector: A straight male BNC crimp connector compatible with cable types RG-174, RG-316, LMR-100. A 50Ohm impedance is required while a brass silver plated body with a brass gold plated central pin are recommended to get a maximum of 500 mating cycles. For these connectors maximum cut-off frequency is at 4GHz with a typical 500V operating voltage. The usage of PTFE insulation ensures a maximum voltage of 1500V. Detailed specifications are available in the following table:
  
  

  Mechanical and electrical specifications
  Working Voltage	500 V
  Proof Voltage	1500 V
  Frequency Range	up to 4 GHz
  Impedance	50 Ohm
  Mating Cycles	500
  Cable type	LMR-100, M17/119-RG174, RG-174, RG-188, RG-188A, RG-316
  Termination style	Cable - Crimp
  Orientation	Straight
  Body material	silver plated Brass
  Insulator	PTFE

  
  A suitable part is provided by Amphenol (no. 112132S) The corresponding datasheet and relevant information are available here.

Adapter Specifications

• SMA male to SMA male adapter: A straight RF SMA plug to SMA plug adapter, rated at a frequency greater than 10GHz, is required for direct connection of the second stage amplifier to the sensor board. Voltage proofing can be limited to 1500V since the part is attached to the signal output line. Insertion loses should be kept to a minimum to limit signal degradation.
  
  Main electrical characteristics of a recommended part are presented in the following table:
  
  

  Electrical specifications
  Working Voltage	450 V
  Proof Voltage	1500 V
  Frequency Range	up to 18 GHz
  VSWR	1.07 + 0.07 x f(GHz)
  Insertion losses	0.04 x √f(GHz) dB
  Phase repeatability	±3° after 1000 mating cycles

  
  A low cost solution is available from RS and can be found here (RS-PRO 546-3282).

• Banana to BNC adapter: Two banana to BNC adapters are required per board, one for the high and one for the low voltage power supply connections. A recommended part should have a rating of at least up to 2kV with a minimum parasitic resistance (typical values of ~10mOhm). An available part for RS can be found here (Telegrapher J01008A0626). If using a third party part, it is recommended to purchase one with clear color coding and additional holes in the input terminals to allow for multiple connections at the same output.
  

  

-- VagelisG - 2017-07-26