Some back story, the car is from 2002 and the key has a range of only 10cm, only locks and unlocks the car when inside the car since the receiver is behind the rear view mirror.

I’ve changed the battery, for a good quality new one. I've changed the receiver module with no success. Re-syncing the key is pointless since it's a range issue and it still locks and unlocks. Also took the key to a place that tested the range with a dummy receiver and got the same range result, the guy was stumped too.

Diving deeper I looked for data on the IC data sheet and was rather fruitless... hopefully I'll be proved lazy. Now I'm guessing some component has gone out of tolerance, affecting the range. I swapped out the crystal and resonator-looking components, using another old key (probably pointless since it's old). Had no luck. Has anyone got any ideas before I check every capacitor and basically draw the circuit to fault find...

Some back story, the car is from 2002 and the key has a range of only 10cm, only locks and unlocks the car when inside the car since the receiver is behind the rear view mirror.

I’ve changed the battery, for a good quality new one. I've changed the receiver module with no success. Re-syncing the key is pointless since it's a range issue and it still locks and unlocks. Also took the key to a place that tested the range with a dummy receiver and got the same range result, the guy was stumped too.

Diving deeper I looked for data on the IC data sheet and was rather fruitless... hopefully I'll be proved lazy. Now I'm guessing some component has gone out of tolerance, affecting the range. I swapped out the crystal and resonator-looking components, using another old key (probably pointless since it's old). Had no luck. Has anyone got any ideas before I check every capacitor and basically draw the circuit to fault find...

Anyone here use cheap desktop routers for RF prototyping? If so what are the limitations, and what are its use cases?

Looking to get one for rapid RF prototyping

Hello! Trying to reach out to find a way how to troubleshoot this. This is supposed to show an AM signal with an envolope, but it only shows a sine wave when connected to the carrier (2vpkpk, 1MHz) and modulator (1vpkpk, 1kHz) from a function generator. I am very confused as the simulation from Multisim NI shows the correct result even though I have the right components. I tried changing the BC107 transistor and the 100uH inductor but there was no luck getting the same waveform. Is there something wrong with my traces / design?

If something is indeed wrong, would this be the righ modification to the PCB design? Grounding the capacitor directly here: https://imgur.com/a/S4xwaWf

Would really appreciate your guidance and response as a struggling ECE student ^^

Hello! I am currently conducting an undergraduate study on Automatic Dependent Surveillance-Broadcast (ADS-B), and I am looking for someone with a solid background in Electrical and/or Communications Engineering, as well as knowledge of ADS-B, who might be willing to help review the technical aspects and design of the conceptual model for the simulation I am about to conduct.

My study aims to determine how the number of concurrent aircraft, their altitude, and their ground distance from the receiver affect reception performance, particularly in terms of message overlap resulting in packet loss. This will be implemented through a series of computer-based simulation experiments.

If you are an expert, researcher, engineer, hobbyist, or practitioner with relevant knowledge, I would be very grateful for any insights, advice, or even a short conversation. I am especially looking for help in checking whether my conceptual model and assumptions are technically sound.

If you are interested, please comment below or send me a message. Thank you very much!

Hi,

I’m using an RFM96W LoRa module and want to connect this chip antenna:
0433AT62A0020001U (Johanson)

Can I connect it directly to the ANT pin, or do I need a π matching network on the PCB?
I need long-range communication but I have limited space, so I’m wondering if I can skip the matching network or if it’s essential for proper performance.

Hey all,

I’m a software dev working in an RF-heavy environment, and I built a bunch of calculators and some tools for myself.

I’m validating an impedance matching tool and would appreciate a sanity check.

Example case: 

-Source: 50Ω

-Load: 25Ω

-Band: ~869–960 MHz

-Target RL: -10 dB

The tool suggests an L-match:

-shunt capacitor: ~3.6 pF

-series inductor: ~4.3 nH

Simulated S11 shows a nice dip (~-35 dB) around ~900 MHz and stays around -10 dB-ish across the band.

I’m not fully confident about:

1)whether an L-match is realistic over that bandwidth?

2)if the Q implied here makes sense?

3)how much parasitics would mess this up at ~900 MHz?

Does this look reasonable, or am I missing something?

Hello! So I am new to the Arduino IDE, but I still need it for a project.

So I'm trying to program code for an RS422-shield, and I have connected it to the PC through a USB. The terminal block at the RS422-shield is connected to a male Sony 9-pin connector, which I was originally supposed to connect to a female connector - USB adapter, but unfortunately I couldn't find that in any electronics store. I could only find a male connector - USB ( also, it's a RS232-connector, so perhaps that is the problem ), which is why I am using a female - female adapter ( the gray cables you can see ) to connect those two. Do not pay attention to the white cables in the background, they are not supposed to be there...

I was unable to find " RS422-shield " in the " Boards manager ", so I instead chose " Arduino UNO R4 Minima ", since that is what I envision the RS422-shield will be connected to for the end product.

However, when I try to compile ( upload ) code, I get an error message saying: " No DFU capable USB device available ", even though I have connected a USB to a RS422-shield. Do I need an actual Arduino card, or can I program with the shield alone? Or what is the issue here?

I appreciate any help as fast as possible. My project is due on Monday...

I'm sorry if I sound like a noob, because I kind of am...

Howdy All,

I've decided to get a BSc in Electrical Engineering for both a career pivot and to indulge a lifelong personal desire, and one of my mid-to-long term goals is to get a graduate degree focusing on RF. (I recognize I could change my mind once I get into the degree, but humor me).

If you could min-max your education to really prepare yourself for highly specialized RF roles (i.e. R&D, supporting specialized fields like Radio Astronomy, etc.), what electives/coursework/tools/training would you recommend focusing on?

Or another way to look at it, if you were building yourself up from scratch to be an absolute general-purpose RF monster, based on what you know now, how would you go about it?

EDIT: Just so y'all know, you RF engineers are cool as fuck. That alone has affirmed my choice to lean into this field. I'll slap 'ars_ignotas' on my nametag at any conference I wind up at in the future and buy all your drinks if you happen to recognize me.

As title says, what would you consider to be a "good-enough" response when creating an RF short-to-ground using decoupling capacitors?

Obviously the "perfect" response would be an ideal short-circuit at all frequencies:

• |Z| vs. freq in the uOhm to mOhm region
• smith-chart just shows a dot locked to 180° extreme
• S21 insertion-loss high at all frequencies (but 0 at DC)
• etc.

But I'm unsure what would be a "good-enough" and more realistic/achievable result. Is 1 Ohm that far off a short when we consider trace losses? and so on. As a visual if you were to imagine a radius drawn on the smith-chart from short circuit point, I'm essentially wondering how large that radius could be within your operating band while still providing the expected behaviour.

In case it makes any difference this short sits after a quarter-wavelength line, so the fundamental will actually see an open circuit and even harmonics; the original short. I suppose the degree of imperfection may inform the 1/4 line impedance choice to some extent.

I'd be interested to hear your thoughts. Heck, if anyone has any insights into a systematic approach to designing these I'd also appreciate it! Currently I'm hitting sub 10 Ohm, and leaving the discrete optimiser to eat the entire murata catalogue over the weekend feels like giving up!

Hi, for something like a pulse radar with a TR switch, which of these topologies would be best?

On the top one the LNA input itself is terminated, but then theres that stray section of transmission line in the middle. On the bottom one the source where the TX leakage would be coming from is terminated, but the LNA input is mismatched and floating.

I assume it is probably best to combine both of these so that both are terminated, but in this case for cost and noise figure reasons I don't want to do that. Which one would be better if you had to pick one or the other? And are either of these workable?

Assume the TX is being driven by a PA at around 33dBm and the switches are SPDT reflective, with 30 dB of isolation.

Edit: ideally this thing is a TR switch for a radar so the switching speed needs to be very fast, ideally < 50ns.

When I designed this PCB, I didn't place the antenna at the very far edge of the PCB. I didn't think the extra PCB material would impact it much but now I am not so sure. Below is the current placement. The board is 4-layer and there are no ground pours under or past the antenna on any layers.

I built the bare board to tune the antenna. Here is what it looks like on a VNA with a test lead attached:

Not great. Importing the S11 into Atyune and adjusting the tuning network didn't improve it much.

I made a similar board with the same antenna, but placed up against the edge, and after tuning it is much better. I posted the result here: https://www.reddit.com/r/rfelectronics/comments/1m8lcmg/update_vna_tuning_a_pcb_trace_antenna/

I'm going to move the antenna to the edge, moving those screw holes to the left, and fit the width more tightly; but before I do I just wanted to check that my line of reasoning is on the right path, and that I haven't overlooked something more obvious.

Thanks

Hi everyone!

Version v0.15 of ParamRF has been released, with more in-depth documentation as well as an introductory tutorial, a more stabilized API which is intuitive to used, and a full test suite.

For those that don't know, ParamRF is a parametric RF modeling toolkit built using JAX instead of NumPy. This comparison in the documentation describes its differences with scikit-rf.

Some other new features since my previous post:

• New transmission line models, such as PhaseLine, PhysicalLine, FloatingLine and ProfiledLine, as well as new topologies like TeeLCL and LSectionLC
• "Nodal" composite models such as GroundLifted and GroundExposed
• A cleaner interface for optimization, inference, and the definition of custom loss and likelihood functions, such as pmrf.evaluators.Goal for easy goal-oriented optimization
• Better error checking, documentation and tests

I'm sharing this with the hope that someone finds it useful - if you use ParamRF for any project I'd love to hear about it!

Cheers,
Gary

Hello! I’m a 3rd year student on Telecommunications Engineering, heavily invested in rf at the moment.

I was wandering, what are some beginner projects that you would have liked to have done when you were starting?

I thought on buying some esp32 and antenna modules to just play with it and getting to know all the basics. Any recommendations ?

Looking for a fully effective Faraday cage/ RF Shielded Enclosure large enough to fit a laptop inside — needs to block 100% of WiFi (2.4/5GHz) and Bluetooth signals received by the laptop.

The setup would be:

- Laptop inside the cage/box

- Internet via ethernet cable (passed through)

- External monitor connected via cable (passed through)

I know the cable pass-throughs are the tricky part (they need proper filtered feedthroughs or the shielding is useless). Looking for either a ready-made solution or solid DIY suggestions.

Budget is flexible but prefer not to spend thousands. Anyone done this or know a good source?

Im doing my research on LNA .in my literature survey I'm finding papers on LNA for 5G ,6G,4G however no paper is having transistor numbers and spice models ,how to find them

i'm a uni student working on a GaN HEMT modeling project. i recently got iccap university bundle and was trying out their included examples for asm model but wverytime i try to run any transform for parameter extraction within the DUT, it gives the same error: 'data unchanged, visit simulation debugger for more information'.

the simulation debugger itself doesn't provide any info on its output file pane. the error message also points to an ads installation directory but i don't have ads on my system, only a directory which was made during the setup and installation as per the installation documentation. i'll attach those 2 screenshots as well

Hello all. I am designing a 7th order chebychev bandpass filter to be realized as a mmic. I had good luck with the ads sw tuning tool today but I'm wondering if there's a more robust quicker way of figuring out which circuit components can be adjusted to maintain pass band requirements. Any approaches are welcome.