What causes ripple in cable?

What causes ripple in cable?

Impedance mismatch within the cable, evaluation board traces, and package cause multiple reflections of electromagnetic fields, resulting in the formation of ripples. These ripples are caused due to impedance mismatch at the junctions of these interconnects.

What is RF ripple?

Ripple (specifically ripple voltage) in electronics is the residual periodic variation of the DC voltage within a power supply which has been derived from an alternating current (AC) source. This ripple is due to incomplete suppression of the alternating waveform after rectification.

How do you test RF cables?

Use a multimeter to determine if there is a short or other issue affecting continuity within an RF Cable:

1. Set the meter to the resistance setting with the best resolution.
2. To determine if there is any internal resistance in the meter, cross the black and red probes and note the resistance shown onscreen.

How does a network analyzer measure cable loss?

Steps

1. Turn on Spec An and attach adapters to the tracking generator (TG) output and RF Input.
2. Connect the reference cable to the TG out and RF In.
3. Adjust Span of scan for frequency range of interest.
4. Adjust TG output amplitude and spectrum analyzer display to view the entire trace.
5. Enable TG.

What is echo in a cable system?

Echo subsea cable system is the first-ever subsea cable to directly connect the U.S. to Singapore with direct fiber pairs over an express route.

How do you check RF cable loss?

Cable Loss can be measured using the Return Loss measurement available in the cable and antenna analyzer. By placing a short at the end of the cable, the signal is reflected back and the energy lost in the cable can be computed.

How do you test an RF coaxial cable with a VNA?

To achieve accurate results, it is recommended to configure the C1220 VNA settings as follows: Start -> VNA’s lowest frequency; Stop -> Cable’s maximum frequency; Sweep -> Linear; IFBW -> 1kHz; Power -> -5 dBm. Connect the test cable as the DUT, and measure S11 VSWR and S21 Log Mag.

How is RF insertion loss measured?

During network deployment, maintenance, and trouble shooting phases, insertion loss can be measured by disconnecting the antenna and connecting an enclosed short at the end of the transmission line.

How is cable VSWR measured?

VSWR is a measure of the ratio of the minimum and maximum voltage in the transmission line. As an example, the VSWR value 1.2:1 denotes a maximum standing wave amplitude that is 1.2 times greater than the minimum standing wave value. High reflections cause a high ratio of minimum to maximum voltage.

Why are there ripples in the S21 measurement?

The magnitude of the ripple will depend upon the severity of the impedance mismatch at the interface, and the period of the ripple over frequency will depend upon the length of the cable. Ripple can appear in a measurement of S21 even if the frequency response of the DUT is perfectly flat.

What kind of tests are done on RF cable?

The services include electrical, mechanical and environmental stress testing of products such as a cable assembly, amplifier, RF transmitter etc. However, for the sake of inclusion, we will list down some of these tests to be performed.

How is a VNA used in RF testing?

VNA is RF test equipment used by electrical and RF engineers to measure the electrical characteristic of a complex network. It has multiple transmitter and receiver combination to calculate the gain, loss, reflection, VSWR and impedance of a DUT. Modern network analyzers are capable of performing more complicated tasks.

What is the impedance of Port 1 in S21?

The source impedance driving port 1 must be 50Ω, and the load impedance presented to port 2 must also be 50Ω. Suppose the network is an amplifier. Then S21 measures the gain of the amplifier, with port 1 being the input and port 2 being the output.