r/rfelectronics

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

https://preview.redd.it/iuaqyw1gnjug1.png?width=1466&format=png&auto=webp&s=af347518f4873ed31153c08421637f5e87575ae3

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?

Hi,

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

https://preview.redd.it/p6nlwpw8umug1.png?width=329&format=png&auto=webp&s=3d30941250fcc2542366d6cec879ea68993b48a1

https://preview.redd.it/y2ve17eaumug1.png?width=640&format=png&auto=webp&s=dfbf8bb559698a38b4ea41e7767f09663a704739

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.

https://preview.redd.it/hu7ja0l7jhug1.jpg?width=1024&format=pjpg&auto=webp&s=1238fbc3e956fc9b47533712bfe30964f1cd50bb

I recently received a technical specification for a 200kHz radio system (you will spot the problem instantly , but AI didn't ) . On the surface, the document looked flawless—properly formatted, full of industry jargon, and clearly generated by a high-end LLM.

But as an engineer with 27 years in the field, I spotted the "hollow" center within seconds.

The document was 1 page long, it never once mentioned a Link Budget. It didn't specify the Transmitter Power (e.g., 10dBm). It didn't account for path loss or the receiver's noise floor.

To a layman, the AI gave them a "complete" plan. To a seasoned RF engineer, it gave them a physical impossibility.

The Multiplier Effect: $Skill \times AI$

We often talk about AI replacing people, but we aren't talking enough about how AI amplifies the gap between the amateur and the expert.

The Unskilled + AI: They use AI to generate knowledge they don't have. They don't know that a 200kHz link is meaningless without a link budget, so they don't ask for it. The result is a "flat" specification—it looks like a plan, but it won't work in the real world.

The Skilled + AI: We use AI to accelerate the expertise we already possess. We don't ask the AI "what is a transmitter?" We tell the AI: "Calculate the link budget for a 200kHz system at 10dBm with a -110dBm sensitivity requirement in an urban noise environment."

AI is a Mirror, Not a Guru

The AI is not yet "ready" to tell a client their specification is incomplete. It is a tool that fulfills a prompt. If the prompt lacks the "engineering punch"—the specific constraints like power levels, impedance matching, or thermal limits—the AI will happily hallucinate a generic solution.

The "50 Missing Things":

In any professional specification, there are 50 nuances that only come from years in the lab with an oscilloscope and a VNA. If you don't know those 50 things exist, you can't prompt for them.

The Verdict

Skill doesn't just "matter" in the age of AI; it has become the ultimate differentiator.

If you are using AI to hide a lack of fundamental knowledge, the mask is paper-thin to anyone who actually knows the physics. But if you are an expert using AI to handle the heavy lifting, your "punch" becomes exponential.

True authority isn't about the tool; it’s about having the wisdom to know what’s missing from the output.
#RFEngineering #HardwareDesign #AI #EmbeddedSystems #TechLeadership #EngineeringExcellence #LinkBudget #ElectronicsEngineering

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...

https://preview.redd.it/ossjk92bhlug1.jpg?width=3024&format=pjpg&auto=webp&s=2977a73a0a91fb50f60a6dc28540cfbd8198746f

https://preview.redd.it/orjy8c2bhlug1.jpg?width=3024&format=pjpg&auto=webp&s=c78ff3b8925b62392b68eab7a6ce9a773f455817

https://preview.redd.it/i2tpva2bhlug1.png?width=1037&format=png&auto=webp&s=58f769c1d46c386d8da6f9142484b5a195a3a134

https://preview.redd.it/l1ka8a2bhlug1.png?width=837&format=png&auto=webp&s=91489a73f424dc46481b701b122fb196585ed755