Hi, I am working with long cables with up to 100 nF of capacitance and 15 ohm resistance and I'm trying to understand where my power losses will come from.

Suppose I want to send a communication signal on the 50 kHz range. Besides the resistive power losses, do I have to worry about capacitive and inductive losses as well? In this case, is the dielectric loss (like calculated here: https://mycableengineering.com/knowledge-base/dielectric-loss-in-cables) the only thing I have to worry about?

 

What type of cables? Coaxial, twisted pair, strait wire?

 

What type of cables? Coaxial, twisted pair, strait wire?

It's a coaxial cable.

 

What type of coax? Ex: RG-58, RG-58-A, RG-59, etc.

How long is the cable?

What kind of modulation are you using and what is the bandwidth or bit rate?

Where is the 15 ohms located?

 

The capacitive reactance at 50kHz is about 32Ω, so the reactive current from that will need to be delivered by the source, so any losses from that extra current in the source will add to the source power required.

What is the cable characteristic impedance?

 

I am thinking about the receiving end termination needed to minimize problems with reflections but don't have enough information yet.

 

What type of signal and what is 'long'? At 50 Khz the wavelength is ~6km.
https://www.pulseresearchlab.com/pages/faqs-about-transmission-line-effects

 

What type of signal and what is 'long'? At 50 Khz the wavelength is ~6km.
https://www.pulseresearchlab.com/pages/faqs-about-transmission-line-effects

Thank you for the source! While I had a basic understanding of this topic, I found the text to be highly informative.

DPSK communication over low-voltage DC line.

The capacitive reactance at 50kHz is about 32Ω, so the reactive current from that will need to be delivered by the source, so any losses from that extra current in the source will add to the source power required.

What is the cable characteristic impedance?

50 ohm.

What type of coax? Ex: RG-58, RG-58-A, RG-59, etc.

How long is the cable?

What kind of modulation are you using and what is the bandwidth or bit rate?

Where is the 15 ohms located?

RG-58. With dpsk modulation .

Around 400 m. 15 ohm is more or less the total cable resistance I calculated.

 

RG-58 has a capacitance of about 82pF/m so the total capacitance for 400m of cable is 32nF.
The reactance of this at 50kHz is about 100Ω so your driver will need to drive that load.

The cable inductance at that frequency should have negligible effect.