About
This tool allows create a simple RF system cascade. You may view things such as cascaded noise figure, cascaded linearity (IP3, IP2, P1dB), electronic gain, aperture gain, EIRP, and other parameters.
RF cascade analysis is very commonly done in an Excel document. Many companies have their own preferred Excel document; my goal here is to create a simple, accessible online tool to verify calculations or for new engineers to learn. At first glance, there's a lot going on; take some time to learn the way I'm visualizing the information and allow the user to control what is being viewed. I think you'll enjoy using the tool and I hope you share it with others.
This tool was created by Jason Durbin, a free-lancing phased array engineer.
Usage and Terminology
- System blocks may be added using "Add Block". The block Type controls how the backend treats it during the cascade. There are multiple types:
- Active - Control gain, noise figure, and linearity settings.
- Passive - Control gain and linearity settings. Gain must be less than 0 and the noise figure is directly related to gain.
- Corporate Combiner - This block requires the system direction to be "RX". An extra parameter appears ("inputs/outputs"). For example, a 2-way would be have 2 inputs. Gain is the insertion loss of the device not including the split loss. During system calculation, this block assumes the signal is coherent and noise is incoherent. Therefore, this block should improve SNR. Additionally, this block increases element count (and therefore aperture gain). Note, if your system is not a phased array, this block is unneccessary.
- Corporate Divider - This block is reciprocal of "Corporate Combiner" for TX. Similarly, gain must be insertion loss not including split loss. Unlike the combiner, noise and signal power are not treated differently through this block. Note, if your system is not a phased array, this block is unneccessary.
- Combiner - A combiner that is not treated special. Element count is not affected by it. Loss through the combiner is the number of inputs + gain. Essentially this is an amplifier with linear gain equal to the number of inputs.
- Divider - This block is reciprocal of "Combiner". This block is essentially a passive lossy device.
- Antenna - A special block that increases aperture gain, signal gain, but not electronic gain or noise figure - essentially an antenna with perfect radiation efficiency. If you have radiation efficiency, consider adding a passive block immediately following the antenna. Antennas should be the first element in RX or last element in RX.
- Single Path vs Coherent
In this tool, I carry terms for single path noise figure and gain and coherent noise figure and gain. This distinction only applies when looking at and RX system. Coherent implies that all devices prior to corporate combiner are all operating identically and their noise is random; therefore, the signals add coherent (in power) and the noise adds incoherently (in voltage). Single path is the performance if all elements are off except for one. For example, single path gain is what you'd measure with a network analyzer connected to one input.
- Electronic gain vs array gain vs signal gain
- Signal gain is simply the how much the signal power has increased through the system. All devices impact the signal gain.
- Array gain is simplified directivity estimate of the array. Some people carry this number as negative noise figure (because that's what it is).
- Electronic gain is the gain of all the devices that contribute to noise. If you remember from Pozar, the noise at the output of a device =
g_linear*(kTB + noise_input). For a phased array, the gain in that equation (g_linear) is electronic gain. - More simply, if you were to replace the entire phased array with a single amplifier and a single antenna, the amplifier would have a gain equal to electronic gain (and a noise figure equal to coherent noise figure), the antenna would have a directivity equal to array gain, and the signal from left to right (or vise-versa) would increase by the signal gain.
- System globals control things like system temperature, direction, bandwidth (for noise), input signal power, and input noise temperature.
- Columns can be rearranged or hidden as necessary.
- You can add system plots for most columns.
- Hover the column header or column selectors to show a description of the parameter.
- The Y-axis of plots is controlled by the unit selected in the column. Changing the unit of a column will change the unit of the plot.
Notes
- This tool is not intended to replace more advanced system simulation tools.
- While I try my best to test every feature and verify the mathematics, there's a potential of errors. If you see one, contact me.
- This tool uses a delicate balance of saving raw data to URL (or clipboard). Sometimes, random errors may occur. If you happen to be able to replicate an error, contact me!
Other Resources
- Microwaves101 System Calculator and their in-depth page on RF cascade analysis.
- RF Dude's RFsyscalc.
Commercial Use
This tool or any derivatives of this tool may not be hosted on commercial websites (internal or external) without approval. Of course, you are welcome to share the URL.
If your company is interested in a bespoke version of this tool on your website, please contact hello@neonphysics.com
Commercial use is otherwise prohibited.
Donation and Feedback
If you enjoy this tool, please consider donating using PayPal.
If you have any recommendations, feedback, or requests, feel free to send Jason a message on LinkedIn or send an email to hello@neonphysics.com.
Attributions
- Colormaps are from Paul Tol's Color Scheme or matplotlib.
- Icons are from Tabler Icons.
Tracking and Proprietary Information
I use a self-hosted version of Matamo to track viewers and analytics. I do not sell any information and I only use the information for my personal understanding of usage to better improve the tool.
Please note: because the settings are saved in the URL, I can personally view and replicate any configuration. If you or your company deem any configuration to be proprietary, I do not recommend sharing the link. However, I have intentionally not included things like frequency to avoid this concern.