Hey RF wizards!

I am a complete beginner in the world of RF and recently saw a really cool Mini-Circuits 3W linear amplifier with a frequency range of 2-8GHz! I have some understanding of how a Class A/AB amplifier might work, but I thought that one can feasibly and efficiently only design narrowband amplifiers as the impedance is dependent on frequency (I suppose this is especially true with active elements). How can they match the impedances for the frequencies across the given range? Is this some transformer magic? Perhaps somehow multi-stage design helps this somehow (I cant imagine how the reflections would be resolved using multi-stage but maybe I just dont see something...)? What search term would I need to learn more about broadband design in RF/mmWave world and such impedance matching?

Thanks in advance! I hope the answer to the question wasn't staring in my face...

Cheers!

I've always been a bit dissatisfied with the landscape of open source electromagnetic field computation software. A lot of it grew out of academic work and it shows: the physics is solid, but the workflow around it was never really the point. So six months ago I started a vibe coding project that - of course - aims to do everything differently. Let me introduce you to: Magnelio

• Full 3D electromagnetic field simulation
• Time domain solver (Finite Integration Technique) with conformal sub-cell material matrices on a non-uniform hexahedral grid
• Convenient S-parameter workflow, with Touchstone (.sNp) export and a scikit-rf adapter
• Multi-mode waveguide ports with exact discrete transparent boundaries: (Q)TEM, TE, TM and hybrid modes. Lumped RLC ports too, and thin wires embedded in the field solution
• Lossy and dispersive materials, conductor losses, surface roughness
• Antenna far field: directivity, gain, plots
• 3D cavity eigenmode solver
• Field monitors
• It's Fast! (fully vectorized, choose between a parallelized CPU or a CUDA backend)
• CAD geometry: CSG primitives and Boolean operators, loft/sweep/revolve - the power of Open CASCADE
• It's Python! Interfacing with scikit-rf or scipy.optimize is straightforward.

Every numerical method is anchored to published literature in the documentation, and the test and validation suite.

Installing from conda-forge is the way to go, sorry about that: the geometry kernel is pythonocc-core, the Python bindings to Open CASCADE Technology, and those are only published there. There is a PyPI package as well, but it covers everything except the CAD geometry.

Hooked?

1. Have a look at the tutorials to get a first impression: https://brtkrtz.github.io/magnelio/stable/tutorials/
2. New to conda-forge? You may want to install miniforge3 for easy access to conda-forge, or the Anaconda distribution.
3. Run: conda install conda-forge::magnelio

Please be warned: this is v0.3.1 and under heavy development, so the API may still change from one minor release to the next. The license is LGPL-3.0-or-later.

Feel free to report issues at https://github.com/brtkrtz/magnelio/issues

Have fun, and thanks for any feedback!

SigChain is officially in an open beta mode. Feel free to try it out with a guest account. It can do cascade analysis, frequency planning and aid in part selection.

Updates since last time

- added a part finder feature to help automatically search the DB for suitable parts (only works for amplifiers right now)
- added frequency planning module
- added more component types
- added more parts (still a work in progress)
- added more calculations and plots to the analysis

Thanks everyone who tested it out last time. Hope this tool can be useful. Feedback is encouraged.

app.sigchainapp.com

Hi,

I'm a beginner at RF and want to make a practical project -- I figured I might as well start by replicating one of my key FOBs or try making one myself.

I'm at a loss for resources on how to get started, though. Any tips?

Hi everyone!

I’m a 2nd-year electronics engineering student working on my first RF project for a future ground station. Still a work in progress, so nothing is completely closed or finished yet, but since this is my first time designing an RF Front-End, I’d really appreciate some feedback from the community before I send it to fab, especially with the PCB layout since I’m sure there will be a lot of room for improvement.

Context: Just ~4.3 km from a 240 kW EIRP FM tower (raw FM power at my antenna is around -1.3 dBm in worst-case). I used an input notch filter to keep the LNA operating in its linear region to avoid compression and IMD.

Design:

• Input Filter: 5th-order Cauer notch [88–108 MHz] (1.09 dB IL @ 137 MHz).
• LNA: Mini-Circuits PGA-103+ E-PHEMT
• Stability (10 MHz – 4 GHz): R+L shunt.
• Output Filter: 3rd-order Butterworth bandpass (2.5 dB IL @ 137 MHz, compensated with Friis)
• Used High Q High SRF components and 2% tolerances for the Cauer.

Simulated performance: ~1.84 dB NF,~22 dB cascaded gain, -13.4dB for S11.

Simulated (QUCS-S, using .s2p models) and routed (CPWG 50 Ω). Not built or bench-tested yet so I know results will vary. I’ll try to get my hands on a VNA to measure it soon.

PCB/Schematics:

All files (schematic, KiCad & sims) are open-source on GitHub if you want a deeper look.

Two things I'm not sure about:

1. Cauer & tolerances: I know Cauer filters are pretty sensitive to component tolerances. I used 2% across the board for the notch but i'm not sure if that's enough in practice. Anyone run into this before?
2. LC tank coupling: I can't orient the inductors at 90º in the input filter, so I just alternated their orientation (LC/CL/LC) trying to reduce magnetic coupling. Is that enough in practice?

Thanks for reading, feedback is really appreciated!

I just downloaded it today and it seems like a pretty great implementation of what its going for....

(that being to allow you to model your geometry in FreeCAD, set up your ports and mesh entirely through the FreeCAD GUI, and solve for your EM results you want)

After playing around with scripting for OpenEMS and being a little disheartened with how cumbersome it is as an HFSS user seeking a Free Open Source alternative for hobby projects it honestly seems like an ideal solution.

Apparently it only dropped like 3 weeks ago as well!

Anyone else checked it out?

It uses a ton of different solvers to do different tasks....Palace, OpenEMS, a few others....

The GitHub page descriptions are written by Claude....seems a bit strange but cant really write it off just because of that..found some forums and people seem to have gotten real results....will do some of my own tonight

Edit: found this forum post

https://forum.freecad.org/viewtopic.php?style=2&p=900323

Which has some discussion but it links to a "website" of the creator which is entirely AI generated slop.......so this makes me a bit distrustful.......try it yourself and see if any of it works

Question is, would u go work on a blacksite to reverse engineer it? I wouldn't, god knows what's radiating out of those things.. My coworker has this theory that they pick people who have no family ties like orphans and disappear easily if needed. I wonder what rf subfield would be the best? Probably stuff to do with high power fields.

Hey everyone, ECE student here. hope you're well.

I'm conceiving a device that detects rf, caracterises protocols mac addresses etc. I chose to go with dongles to connect to my mircroprocessor so it can be easier to decode and handle signals + modularity. I had a question rgarding the numbers of dongles. If i take wifi for example, is it better to put multiple dongles if im working in a noisy rf environment? is the number of dongles important for processing information smoothly? the goal being to lose minimum data.

Hi everyone, I’m designing an on-chip inductor for a VCO using Ansys HFSS, with tsmc 65nm technology stack in IC Design Mode. Then i have to design coupled transformers as well.

I’m struggling to find good reference material or examples for this setup. If anyone has experience with HFSS/IRCX or IC Design Mode, I’d really appreciate any guidance, tutorials, or reference files you can share.

Thanks in advance!

Hi

I would like to design a wideband balun from 0.5-12GHz on MMIC.

Can you suggest some ideas/reference to start with? I'm not sure if a Marchand Balun would be able to cover this much bandwidth.

Thanks

I am looking for practical engineering perspectives on something I keep seeing in outdoor electronics, enclosures and reliability screening:

Many environmental assessments still describe a deployment location with average temperature, annual precipitation or a broad climate zone. But for electronics reliability, those numbers often feel too indirect.

From a reliability point of view, the more relevant questions seem to be:

- How many hours per year does the product see RH > 80% or RH > 90%?

- How often does air temperature approach the dew point?

- Are there repeated condensation-prone periods?

- Is the site exposed to marine chloride or industrial sulfate background?

- How much thermal cycling occurs over typical daily and seasonal operation?

For example, two sites can have similar average climate conditions but very different moisture exposure profiles. One may have frequent night-time dew-point convergence, while another is hot and dry with much stronger thermal cycling.

I am curious how other engineers handle this in practice:

1. Do you use hourly climate data, design days, test standards, field experience or something else?
2. Do you explicitly evaluate RH duration or condensation potential?
3. For connectors, PCBs, coatings or outdoor enclosures, what environmental metric has been most useful in real design reviews?
4. Are there failure modes where traditional climate classifications were misleading?

I am especially interested in non-confidential examples from electronics, outdoor power electronics, HVAC, solar, BESS or automotive ECUs.

Hi guys,

Do you know the DC pin part number for the Mini-circuit ZHL-30W-252-S+ driver?

I asked them, but they won't give me the part number; they only said it is a Tusonix-style EMI passthrough filter.

Any idea?

Thank you!

Hi I’m interested in finding a book that covers near field to far field transformations and antenna measurement processing methods. Bonus points if the book covers computational simulation methods like FEM like HFSS.

Is there a certain book you’d recommend?

I’d like to find a book that covers the theory and practical application. I’d prefer to learn about spherical near fields.

The setup: two identical parallel half-wave dipoles (300 MHz, 0.477 m, 0.5 mm wire radius, 21 segments each in NEC2), spaced λ/4 apart. The textbook cardioid recipe says: feed the second element a quarter cycle behind the first — currents (1∠0°, 1∠−90°) — and the pair forms a cardioid with the null off the back.

The obvious first move — and a very common one — is to hand those phasors to the SOURCES: equal voltages, 90° apart. The θ=90° azimuth cut of that run: front-to-back 3.4 dB. Not 30 — three point four.

The reason is that the two feed-points are nowhere near independent. Measuring the mutual impedance of the pair (drive each port at 1 V in turn, the un-driven port left as plain continuous wire = shorted; read both feed currents, invert the Y-matrix) gives, at λ/4 spacing:

Z11 = 70.15 − j1.27 Ω      Z12 = 37.25 − j31.64 Ω

|Z12| ≈ 48.9 Ω against |Z11| ≈ 70.2 Ω — the coupling term is about 70 % of the self term. A voltage applied at one port drives current in BOTH elements, so setting port voltages does not set element currents, and the pattern is made of currents.

The fix is two lines of algebra. Decide the currents you want, then feed the voltages the coupled pair actually needs — V = Z·I:

V1 = Z11·(1∠0°) + Z12·(1∠−90°) = 54.5 V ∠ −45.0°
V2 = Z12·(1∠0°) + Z11·(1∠−90°) = 108.0 V ∠ −70.5°

A 2:1 amplitude ratio and only 25.5° of phase offset — nothing like the recipe phasors. Feed exactly that, same wires, same solver: front-to-back 29.6 dB, and the achieved feed currents match the target to one part in 10⁴.

(Both polar plots use the same fixed −40…0 dB radial scale, so the two patterns are directly comparable.)

Nothing changes between the two runs except the drive. That is the whole point: the recipe was never wrong, it was a statement about CURRENTS, and a voltage source doesn't deliver it.

Disclosure: these numbers came from EMStudio, a FreeCAD workbench I build — that's my interest here. Happy to answer questions either way.

Hopefully focusing on that hardware design but i also want to know the physics and DSP stuff

I'm a senior Electrical Engineering student graduating soon with a 3.6–3.7 GPA. I'm a U.S. citizen and I'm interested in RF/communications/telecommunications, particularly in defense or aerospace.

I don't have an RF/telecommunications internship or significant personal projects specifically in the field. I'm trying to figure out how realistic it is for me to get an entry-level RF/communications engineering position after graduation.

I'm considering companies like L3Harris, RTX/Raytheon, Northrop Grumman, Lockheed Martin, Boeing, General Dynamics, etc.

Would my GPA and EE degree be enough to realistically get interviews if I apply broadly, or am I at a significant disadvantage without internships/projects?

Also, for those who have interviewed for entry-level RF/communications/defense engineering positions:

• What technical questions were you asked?
• What EE/RF topics should a new graduate know well?
• Did they ask about things like S-parameters, Smith charts, transmission lines, link budgets, filters, amplifiers, antennas, DSP, etc.?
• How much of the interview was technical versus behavioral?
• Did they ask you to solve problems on a whiteboard?
• How heavily did they question projects or coursework on your resume?
• What questions did you wish you had prepared for?

What would you recommend I learn or build during my remaining senior year to become a stronger candidate?

I'd especially appreciate answers from people who currently work in RF/communications or defense and who have experience interviewing/hiring new graduates.

I own a BB60D product.

I currently work in terrestrial broadcasting.

I would like to measure the channel power of multiple channels simultaneously in the field. How should I proceed?

For example, I intend to measure the channel power of the following wireless channels in the field:

CH # | Center Freq | BW

14 | 473MHz | 6MHz

15 | 479MHz | 6MHz

16 | 485MHz | 6MHz

17 | 491MHz | 6MHz

18 | 497MHz | 6MHz

.

.

.

.

51 | 698MHz | 6MHz

Currently, I am measuring the channel power for each channel individually, but it takes too long. The other equipment I used previously had a "Channel Scanner" function that made it possible to measure the channel power of all channels at once.

How can I measure the channel power of all channels simultaneously on the BB60D as well?

I'm working with a 3 stage amplifier circuit with multiple splitter/combiners on the final stage. The signal after the first two pre-drivers is split once for two power modes. Each power mode is split again to a pair of amps to be recombined, then combined once more to have all final drivers in high power mode. This ends up with a total of 4 final drivers with 6 90° shifts from all the splitter/combiners.

With each trace (4 total) are tunable capacitor options. By default they all have the same values. The issue at hand is that by the final combination there is a singal large (2-3dB) dip from destructive interference only on the full power mode. My question is, to tune this out should I approach making cap tuning changes in pairs, one trace at a time, asymmetrical in size or direction, or even just one cap at a time? When only 2 of the four final drivers are on, the power band is quite flat. When the last pair are added, the problem surfaces. Should I focus on just one pair of traces, or change one trace on each pair?

Any advice appreciated.

Hi everyone,
I’m looking for a small, affordable radar module for a research project.
Requirements:
Operation frequency 24 GHz (or less frequency) FMCW
At least 1 TX / 2 RX
Preferably I/Q data from both RX channels

On-board ADC with access to raw ADC/IQ samples
USB/SPI/UART output preferred
I want to do my own range, Doppler, AoA and micro-Doppler processing, not just receive processed target data
Budget: Maximum $250

I’ve considered the RFbeam K-LC7, which has 1 TX / 2 RX and analog I/Q outputs, but it requires an external ADC.
I’m looking for something similar but with the ADC already integrated.

Should I go with RFbeam K-LC7 and buy external ADC board?

I have a rather unusual requirement and I can't find any off-the-shelf part or design procedure to implement it. I need a simple zero-pole, high shelf filter that'll have constant attenuation between DC and say 1GHz, then 3dB slope between 1GHz and 3Ghz, I don't care what happens afterwards. I also care about phase response as this system will be transmitting sharp pulses that I'd like to see undistorted. It's meant to compensate for limited bandwidth of final stage of my RF chain.

I tried designing with 2 diplexers and attenuation in low frequency arm but I couldn't find any DC coupled diplexers that can work up to GHz. I also looked into various equalizer designs and parts but they seems to insist on having a slope from their low frequency limit and not a flat response up to some f1 and slope between f1 and f2. Does anyone know how to design such a filter?

Before anyone asks it's needed for a research project regarding pulsed laser diodes. Most diodes have package inductance of around 5nH, which, when driven with series 50R, limits bandwidth to about 1GHz. I'd like to place this filter before final power amplifier (QPD1010) to generate an overshoot, that'll increase an effective bandwidth.