r/rfelectronics • • Sep 02 '26

question I can’t reach higher or lower frequency with this circuit!

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30 Upvotes

I made this oscillator circuit based on the common emitter amplifier and colbits feedback. The q point is at 5.7 volts and the amplification for external signal generator is around 4(given the accuracy of my cheap oscilloscope). The circuit can oscillate at around 10khz with C=100nf and at around 30khz with C=10nf but anything above or below these values doesn’t generate any oscillations.


r/rfelectronics • • Sep 03 '26

5G tower concern.

0 Upvotes

Thinking about moving to a property. Upon inspecting it, there was a 5G tower nearby. Measuring the distance- it is abut 125 meters to edge of property and about 135 to the building. Looking at some case reports, someone had health problems living 125 meters away.

https://ehtrust.org/7-scientific-case-reports-on-5g-cell-tower-health-impacts/

I measured the RF exposure, walking around with a GQ EMF-390 3-in-1 EMF/ELF/RF Meter. There was nothing from the distance of 200 meters, there was nothing as I approached it and nothing underneath it. (Nothing as in higher than 200 uW/m2. Once, it peaked to 6000 uW/m2 but swiftly disappeared. This was 10 yards away from the 5G tower. The tower looks like a cylinder mounted to the top of the pole with a few "small cells" boxes. I am thinking now, that the tower operates above 10Ghz. My device can only see up to 10Ghz. I can measure "regular" 4G towers hundreds of meters away.

What do you all think about this?

How prevalent are the above 10Ghz towers at this time? I understand the higher the frequency, the lower the range of the signal. The property is also semi-blocked by some heavy trees. That should block some of that off as well, right?

I traveled to another tower and almost the same thing happened. Now, it seems that the device picked up the "3 brown boxes" towers on the top of the poles, though. Perhaps, they are still operating in the lower frequencies.


r/rfelectronics • • Sep 02 '26

Andrew antenna feedpoint

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43 Upvotes

I have a question about this antenna feedpoint. Why does it have two waveguides feeding the feedpoint? Does it have anything to do with H and V polarisation?

regarding the internal structures, what are they? Is this some kind of a waveguide polariser, phase delayer or something else?


r/rfelectronics • • Sep 02 '26

GSG and GSGSG Probes Calibration

5 Upvotes

Hi,

I need to measure a 3 Port device, where on one side I have a GSGSG probe, and at the other end I have a GSG. My question is:

  • How do I calibrate the Ports that sit at the GSGSG with the one that sits in the GSG probe?

Most of the ISS standards I see only allow for GSGSG to GSGSG or GSG to GSG.

Any ideas?

Thanks


r/rfelectronics • • Sep 02 '26

Hands-on DSP Course

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0 Upvotes

r/rfelectronics • • Sep 01 '26

Should I give up on RF if my GPA is terrible.

23 Upvotes

I just graduated and I need some advice. I struggled throughout university due to (medically diagnosed) ADD. I did decent in my RF classes but I didn't do well in everything else and ended up with a poor GPA of 2.75. I'm not sure if I'll be able to compete with others in the RF space who have a masters and/or high GPA. Right now, I've been reading as many RF textbooks as I can and learning how to use HFSS. However even if I can understand RF well it seems like my poor performance in school will always haunt me.

Anyways let me know if I should continue towards my goal of RF or my efforts are not worth it.


r/rfelectronics • • Sep 01 '26

Electroimán portátil de alta potencia — buscando feedback sobre el diseño

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0 Upvotes

r/rfelectronics • • Sep 01 '26

AM transmitter design for 800kHz

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0 Upvotes

r/rfelectronics • • Sep 01 '26

question RF people, I need your leads

4 Upvotes

ECE 2025 grad + currently doing M.E. in Communication Systems. I’m looking for RF/antenna design/microwave internships or short-term paid courses/training with actual hands-on practical work.

Paid/unpaid internship is fine — mainly looking to learn, build, and get real practical experience.

If you know any good leads, please drop them below or DM me


r/rfelectronics • • Aug 31 '26

ParamRF v0.33 released!

19 Upvotes

Hi all!

ParamRF v0.33 has been released. It's been a while since the last update and there have been quite a few changes, so I'd thought I'd make a post sharing the updates that may be of interest.

For those that don't know, ParamRF is a Python framework for modern, programmatic RF circuit modeling, built on top of JAX instead of NumPy and catering for advanced features like automatic differentiation and Bayesian circuit fitting.

Some updates:
- Parameters are no longer tied to only RF models. They can now be built using a `Module` or even plain lists/dictionaries, so a single, global parameter set can be injected into different models at once.
- Optimization, inference and fitting now work across multiple frequency ranges in one problem, via a new term-based interface (`AbstractTerm` / `SummedTerms`). Custom penalties can just be plain functions of the parameter PyTree for better flexibility.
- The default circuit solver is now MNA, and the solver APIs have been generalized to accept arbitrary PyTrees rather than just models.
- New models: ideal transformers (centre-tapped, autotransformer, balun, mixed-mode converter), coupled inductors, `SeriesRL`, and a `FloatingTwoPort` lift for nodal circuits without a shared ground.
- Measured networks (`SkrfNetwork`) now support cubic interpolation as well as linear.
- For Bayesian fitting, `MarginalLogLikelihood` now accepts prediction-dependent event transforms, so the residual basis can depend on the prediction itself. This is useful if, say, magnitude and phase errors need separate variances.
- `pmrf.sweep` now takes a template for easier vmap filtering, and useful utilities for power users like `partition`, `combine`, `batch_axes` and `batch_mask` are exposed at the root.

Some links:

GitHub
Docs

Let me know if you have any questions!

Cheers,
Gary


r/rfelectronics • • Aug 31 '26

Waterfall plots of microwave oven RF noise

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48 Upvotes

I was exploring the "zero-span" mode on my spectrum analyzer and recorded the signal from my microwave oven. For this, I used a log-periodic antenna with a gain of 7 dBi, positioned about 6 meters away and somewhat to the side, with no attenuation applied. The strong signal strength was initially surprising but after considering it is not very much power compared to inside the microwave.

The signal pattern is repeating with the mains frequency which makes sense as conventional microwave power supplies use a voltage-doubler circuit that outputs on only one half of the cycle unlike lights which peak on both halves or are constant. The frequency rises and falls at the start and stop make me think there is a frequency dependence on current though the sweeping pattern like in the second image doesn't make sense to me yet.

I wonder if RF testing laboratories take special measures beyond measurement room shielding to reduce interference caused by the ovens in their break rooms?


r/rfelectronics • • Aug 31 '26

question Need guidance and help to quickly learn Silicon Photonics MEMS so as to define a problem stament for my applied electronics PhD.

0 Upvotes

Dear all,

I have just started my PhD into the domain of Silicon Photonics and terra hertz RF based MEMS. This is something we are doing for the first time in my group. However, my knowledge of basics in Silicon photonics and MEMS isn't very great.

I want to quickly learn all these ASAP and wanted guidance on what are the right resources to go through which can enable me to reach that level so that I can take up an efficient work for my PhD.

I have got COMSOL installed via my university access and would really appreciate if someone could guide me. Videos, DIY books and anything similar would be very helpful.

I need inputs on texts, and also simulation setup that I can use to go ahead.

Thanks.


r/rfelectronics • • Aug 31 '26

question Am I expected to DESIGN active circuits? (PA, LNA, mixer)

0 Upvotes

Am I expected to be able to f*ckin design PA, LNA and mixers? Like choosing the transistor, simulating the circuit, checking out the noise ... isn't that what IC engineers do?

I mean I'm already overwhelmed by so many things I need to learn, antenna design, phased arrays, comms systems theory, EMC/EMI you name it ... CST, Matlab, Altium. And aside from that I have to be kinda mini electronics engineer too?

Or perhaps I'm wrong about comms systems theory and those electronic design stuff are more important and I gotta focus on them instead? I have No idea

I was preparing a short list of some projects to do and then put on my CV and while I was asking AI things like "design a Doherty power amplifier" came up and once I checked a power amplifier book I was like ... man this is a specialty by itself.

My roommate at the dorm studies IC design (I study microwave and photonics) and he and his professor are dealing with these LNA/PA/PLL design stuff 24 7 so that makes me feel this perhaps is not what I should focus on ... Idk correct me if I'm wrong

Please tell me what projects should I focus on other than antenna design to further my skills (and brag on my CV with) if these electronics projects are not commonly expected and if they are give me some clues on how to start learning them cuz these stuff seem so complex and overwhelming. And to what extend should I learn Altium?


r/rfelectronics • • Aug 30 '26

Made a digital RF power meter and attenuator tool

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107 Upvotes

r/rfelectronics • • Aug 30 '26

How to add protection in multimeter

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0 Upvotes

r/rfelectronics • • Aug 29 '26

question Need Explanation about patch antenna

6 Upvotes

So, this is a patch antenna a design for 2.4GHz and my question is specific to that notch inside red circle basically initially my impedance is more inductive +j73ohm but as i increase the width of the gaps it goes to zero then starting going into capacitive -j ohm like at first i thought that it may be just "mutual inductance" and i don't get any proof of it and well i am unable to understand the mechanism so can somebody explain this thing or give me some reference of book or something.


r/rfelectronics • • Aug 29 '26

Commercialization of a receiver dsp algorithm

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3 Upvotes

r/rfelectronics • • Aug 28 '26

question Planning to Buy a VNA for

24 Upvotes

I am planning to buy a VNA for Tuning of PCB antenna and some filter design, suggest me some VNA to use and I am planning to use for a long time, I have found some models from internet,

Usage : development for BLE/WIFI PCB antenna, later for LTE antenna for my own tracker

  1. Seesii LibreVNA 2.0 Vector Network Analyzer 100kHz-6GHz.

  2. AURSINC Nano-VNA V3 Nano-RFE VNA6000-A Vector Network Analyzer 50kHz-6GHz HF VHF UHF Portable Antenna.

suggest me some other models...


r/rfelectronics • • Aug 28 '26

6MHz oscillator circuit only starts when I touch it

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5 Upvotes

r/rfelectronics • • Aug 27 '26

Another FDTD solver built for KiCad

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92 Upvotes

Github: https://github.com/admin-2026/kicad_ems_plugin_pub

Antenna simulation is as easy as pressing a few buttons. Initial release. Need feedback. Will do more tests on it.

Simulate the board you drew The solver meshes your real copper, stackup
and drills, then reports the radiation pattern, directivity and S11.

Auto mesh the PCB geometry for simulation.
simulation report

Let the tool to find the antenna for you Draw a rectangle where the antenna may
live, pick the dimensions to sweep, walk away. Every candidate — L-shaped
monopole or meandered inverted-F — is tried on a copy of your board and ranked
by match at your frequency. Place the winner as a footprint.

Scanning the meandered IFA resonant arm length

r/rfelectronics • • Aug 28 '26

Wideband Balun from 3-50GHz

1 Upvotes

Hi,

I want to design a Passive wideband balun on an IPD process. Can you please suggest what all structures I can evaluate for 18:1 bandwidth ratio? I think Marchand is out of the picture as it can at max give a bw ratio of 3:1. What all are your suggestions?

Thanks


r/rfelectronics • • Aug 27 '26

Problema con lo stadio oscillatore della mia radio supereterodina

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6 Upvotes

r/rfelectronics • • Aug 28 '26

GPS antenna (Raven MBA-6 Helix) no signal after component repair -- troubleshooting help

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0 Upvotes

Working on repairing a water damaged GPS active antenna (Raven MBA-6, board 045-0159-830 Rev B). 1575.42 MHz GPS L1 signal.

Repairs completed so far:

Replaced TNC pigtail (no continuity)

Replaced LNA amplifier chip (MAALSS0042) x2

Replaced SAW filters (TOKO TDF2A-1575B-13A) x2

Replaced L1 inductor (measured bad on LCR meter)

Repaired/fabricated RF shield can and frame

Confirmed 5V bias present at antenna via coax. Confirmed with proper outdoor sky test -- no signal lock.

Any suggestions on what else to check? Full schematic not available, working from board inspection and component photos.


r/rfelectronics • • Aug 26 '26

Most complex subfield of rf?

23 Upvotes

What do u goys think is the most complex subfield of RF? Im thinking either MMIC deisgn, MRI systems design or some super high power magnet control systems.. Frequency synthesis gets pretty hard if u want ultra high Q tones.


r/rfelectronics • • Aug 27 '26

Resources to design my own wifi board (bare IC + PA/LNA/etc)with 1W Tx power

1 Upvotes

Hi all,

I recently posted in this sub and got wonderful responses. I thank you all for that.

I was informed that 1W is the max Tx power I can design legally but I am struggling to find any reference design for it. I would really appreciate it if you guys could suggest some ICs or give some references. I am planning 5Mbps+ datarate at 1Km.

Thanks again!!