I have to connect two devices with multiple coax cables each carring a signal that has frequency components ranging from DC to a few GHz. I don't know how to avoid ground loops with this type of connection, this answer(https://electronics.stackexchange.com/a/192554/205214) says to break a ground connection on all but one ground paths but it is impossible in this situation because that would interfere with a return path of a high frequency components of those signals. Is there a solution to this problem?
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1\$\begingroup\$ You can try to make the loop area smaller by running the cables close together. \$\endgroup\$– JustinFeb 21, 2020 at 19:25
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\$\begingroup\$ I'd like to avoid any ground loops but that's what i'm going to do if there is going to be no other solutions. \$\endgroup\$– zakrentFeb 21, 2020 at 19:31
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\$\begingroup\$ What devices would those be? Also, what ground loops you expect to happen? Can you be more specific? \$\endgroup\$– JustmeFeb 21, 2020 at 19:46
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\$\begingroup\$ The source of these signals are some specialized sensors, each has 2 outputs and they will be connected to custom data acquisition system, those signals are hard to work with because they have both DC and high frequency components. I've never had to connect two devices with two coax cables and I think that type of connection can create a ground loop that consists of shields of both coaxes. \$\endgroup\$– zakrentFeb 21, 2020 at 19:59
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1\$\begingroup\$ In addition to keeping them close, as @Justin states, try to keep all cables the same length and arrange the connectors to be equidistant, if possible (e.g. if just 3, in an equilateral triangle). \$\endgroup\$– DrMoishe PippikFeb 21, 2020 at 20:52
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2 Answers
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Some approaches come to mind:
1) use two cables of the same length and twist them together. The goal is to minimize the difference in the dynamic magnetic field exposure between the two coaxes.
2) break the shield at one end of one connector and capacitor couple the shield to the connector. This well help with DC and low frequency loops.
3) measure the currents in one of the braids. If low enough, accept the noise and get on with your project.
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For measuring high frequency ac signals try putting an inductive rf choke in line with your test probes ground wire. (:
