28-FEB-2025
Quick Hands On Deembedding a RF S-Parameter Model for under 1GHz
In RF design, accurately measuring the performance of individual components requires deembedding, removing the effects of external fixtures like connectors and cables from measurements. It is a critical step for validating a designâs true behaviour, but not every project requires high end calibration equipment, especially for quick hands on testing.
For this test coupon example, a simple practical method was used to isolate the S parameter model of the PCB itself. This was done by cancelling out the edge connector influence within the Vector Network Analyser (VNA) calibration step. There are other methods that will be covered in later discussions.
To separate the effects of the connectors, modified SMA edge connectors were used to create a basic Short Open Load and Thru (SOLT) calibration setup:
đš Short Open Load Thru (SOLT) references were created using five edge connectors.
đš For the load, two 0603 100 ohm resistors were soldered in parallel onto a standalone SMA PCB edge connector.
đš To create a through connection, two edge connectors were soldered back to back.
Alternatively, the Test Coupon can be built with separate SOLT features on the PCB.
This method works well for quick validation up to 1 GHz. However, phase wobble creeps in at higher frequencies, highlighting the limitations of this hands on approach as parasitics and soldering imperfections become more significant.
Once we have the deembedded model, we can estimate pcb specifications without the influence of the edge connectors. This leads to more reliable data for refining simulations and ensures better alignment between simulated and measured results.
In more complex designs, S parameter blocks can also be used to model active components, such as amplifier semiconductors. Accurately deembedding surrounding circuitry allows for precise modelling of amplifier behaviour, helping to refine matching networks and improve stability analysis. Component suppliers often provide S parameter models for their components, making it easier to integrate them into simulations.
For higher frequencies or precision measurements, a more refined process is necessary. Tools such as QUCS Studio, ADS, and even Python scripts can help simplify deembedding and improve accuracy.
Do you make use of concepts like this to break a problem into smaller parts?
#RFEngineering #Deembedding #VNATesting #SParameters #SignalIntegrity #TestCoupon #TransistorAmplifier #ElectronicsEngineering #TrueRFInsights
9-FEB-2025
Refining RF Simulations: Assumptions vs. Reality
When designing RF circuits, we often make assumptions to simplify the first simulation and initial build. This speeds up development, but the real learning begins when measured results donât perfectly match simulations.
Revisiting our test coupon post, the first simulation assumed minimal impact from the SMA connector, focusing primarily on modelling the trackwork and pads. However, as shown in the Smith Chart, the simulated (red trace) and measured (blue trace) results donât perfectly align, although they are close. The Magnitude Logarithmic plot of the reflected signal in decibels (dB) shows the difference more clearly.
So, what could be causing the difference?
đš SMA connector parasitics: not modelling them can introduce unexpected effects.
đš PCB dielectric properties shift over frequency: real materials behave differently than idealised ones.
đš Manual soldering imperfections: small variations impact high-frequency performance.
đš Test equipment limitations: measurement accuracy can be a factor.
If the design goal has been met, the time spent refining the model can be time-bound. However, understanding the gaps between simulation and measurement strengthens future designs.
At True RF, we refine our process by âclosing the loopâ between design, simulation, and measured results. Every iteration improves accuracy, and every lesson enhances future projects. Refining the simulation also becomes part of documenting the design for those who follow. At a minimum, notes are be made on why results may have differed from simulation, ensuring continuity and knowledge transfer.
Whatâs an assumption youâve made in a design that later turned out to be critical?
#RFEngineering #DesignValidation #ProductDevelopment #DesignDocumentation #TrueRFInsights
20-JAN-2025
Balancing Design Complexity and Cost: The Art of RF PCB Stackup Selection
When designing RF products, choosing the right PCB layer stackup is a careful balance of performance, manufacturability, and cost. Each layer, material choice, and copper thickness plays a critical role in ensuring the design meets performance requirements while staying on budget.
Simulation tools like QUCS Studio, Keysight ADS, and others allow RF engineers to calculate and model the correct track widths and impedance for specific PCB materials and configurations. However, the real test comes after simulation with a Test Coupon.
Test Coupons are small PCB sections that replicate the transmission line stackup and trackwork, built to verify that simulated results hold true in practice. To assess performance:
1. A Vector Network Analyzer (VNA) measures S-parameters, with the ideal Smith Chart S11 plot showing small circles centered around the normalized impedance (typically 50 ohms).
2. A Time Domain Reflectometer (TDR) checks for consistent impedance. A flat TDR line indicates that the trackwork transitions, cable to connector to PCB, are free of significant mismatches.
Last year, True RF developed a Test Coupon that validated our simulation results. This not only confirmed our design but also became a valuable reference point for future projects. With a little creativity, surplus Test Coupons can even be repurposed for prototyping, adding efficiency to the process.
Selecting the right stackup and validating it with tools like VNAs and TDRs ensures that our designs deliver reliable performance while balancing cost and manufacturability.
How do you or your team balance these trade-offs and derisk your designs?
#RFEngineering #PCBDesign #VNATesting #TDRAnalysis #SimulationTools #DesignValidation #CostEfficiency #CheckTheBackSeat
6-JAN-2025
Understanding the Product Lifecycle Curve
As engineers and project managers, meeting customer and stakeholder expectations isn't just about delivering great products, itâs also about supporting the business case behind them. Thatâs where understanding the Product Lifecycle Curve becomes critical.
This curve illustrates how a productâs profitability changes over time:
1ď¸âŁ Introduction: High prices recover R&D costs, but profits are minimal. Early adopters set the stage.
2ď¸âŁ Growth: Profits peak as demand grows and economies of scale kick in. This is the most profitable phase, before competitors enter the market.
3ď¸âŁ Maturity: The market saturates, prices drop, and competition increases. Margins shrink, and differentiation becomes key.
4ď¸âŁ Decline: Sales fall as newer solutions emerge. The focus shifts to minimizing costs or pivoting.
Why does this matter in developing product?
đ By understanding this curve, you can plan projects that align with customer timelines and stakeholder expectations, ensuring your product hits the growth phase while demand (and profit) is highest.
đ Delivering on time is critical. Delays can push your product into a saturated market, reducing profitability.
đ In the maturity stage, engineers play a vital role in cost reduction, optimizing production, and maintaining quality.
The takeaway: Your work directly influences the companyâs ability to maximize profit and meet stakeholder goals. When we understand the lifecycle, weâre not just solving technical challenges. Product development teams are driving business success.
How do you ensure your projects deliver the right product at the right time?
5-DEC-2024
One to test, One to trust
When it comes to new product development, many businesses adopt a lean approach to maximise efficiency and minimise waste. At True RF, weâve seen firsthand how a thoughtful, iterative process can reduce risks and accelerate innovation.
Eric Ries' book The Lean Startup outlines a simple, iterative framework that we often recommend to our customers, particularly for the earliest stages of development. The process follows these steps:
1. Idea: Start with a clear value proposition and business model.
2. Build: Develop a Minimum Viable Product (MVP). This step is where risk lies, so focus on minimizing wasted effort.
3. Measure: Share the MVP with stakeholders and collect feedback.
4. Learn: Review the feedback, adjust, and prepare for the next iteration.
For early iterations of the Build step, a common missed opportunity is creating only one unit for the proof of concept. We recommend building two units instead. Why? Comparison is invaluable. Having two units allows you to:
⢠Identify manufacturing challenges early.
⢠Spot potential design inconsistencies.
⢠Reduce the risk of overlooking critical flaws.
⢠Review with more than one stakeholder simultaneously.
This small addition to the process provides early warnings of risks, giving your project a stronger foundation to iterate upon. At True RF, we take this approach seriously, helping our customers create prototypes that empower informed decisions and effective adjustments.
#Prototype #NewProductDevelopment #LeanStartup #RiskManagement #ElectronicsDesign #RFDesign #TheBuddySystem
25-NoV-2024
From Cellular Networks to MANET: The Evolution of Connectivity
Most of us are familiar with traditional cellular networks: our devices rely on centralized towers to send and receive data. This point-to-center-point model works well in urban areas with established infrastructure. But what happens when that infrastructure is unavailable?
Historically, radio communication evolved with store-and-forward networks, where radios passed messages between nodes when direct communication was not possible. This was a breakthrough for remote operations and emergency communications.
Today, the next step in this evolution is Mobile Ad Hoc Networks (MANET). Like Mesh networks, MANET enables direct communication between devices. However, while both share decentralized and self-healing properties, they differ in important ways:
1. Mesh networks often rely on stationary nodes, creating a stable web of connections.
2. MANET is designed for mobility, with nodes dynamically forming and adapting the network as they move.
Imagine a team of drones coordinating their flight paths in real time or first responders maintaining seamless communication as they move through disaster zones. This is where MANET shines, offering dynamic topology, scalability, and resilience in challenging environments.
As we look to the future, cognitive radio presents exciting opportunities to push connectivity even further. Cognitive radios are smart devices that can dynamically sense the radio spectrum, identify unused frequencies, and adapt their transmissions to maximize efficiency. By learning from their environment, they can avoid interference and optimize network performance. This technology aligns naturally with MANET, enhancing its ability to perform in crowded or unpredictable environments.
How do you see your industry harnessing evolving radio technologies?
#TrueRF #MANET #CognitiveRadio #MeshNetworks #WirelessInnovation #Connectivity #RFEngineering #IoT #TrueRF #RadioTechnology
11-NoV-2024
Radio System Bench Testing Without Antennas?
Before deploying in the field, it is good practice to perform bench testing on radio systems for an extended "burn-in" period. This helps identify configuration errors and early failures. When testing without antennas, it is easy to overlook the importance of using 50 ohm loads or attenuators. Some might think, "The radio is built to handle an antenna or open load, so what is the harm?" or assume that leaving the antenna off is a form of stress testing. It isnât a great test of normal operation.
Although modern radios have built-in protections, continuous exposure to this kind of stress can still lead to premature wear. The ideal setup is a 50 ohm load to eliminate reflected power, though this might prevent effective communication between radios. Alternatively, using attenuators with or without antennas reduces reflected power and allows stronger signals between radios. The closer the load on the antenna port is to 50 ohms, the less reflected power there will be, which minimizes unnecessary stress and wear on your equipment.
Some radios are designed to lower output power when an open load is detected, and reduce premature wear. In this case, the power supply is not as heavily loaded by transmissions. Lower power supply loading could  mask potential power issues during bench testing.
Whether you are conducting bench tests before field deployment or verifying performance during development, use the right tools:50 ohm loads, attenuators, or antennas. If antennas are used, be sure to select the correct attenuator to maintain safe distances and protect against human exposure to high RF power.
What are you seeking to achieve in bench testing?
Proper load matching and safe testing practices to ensure that your equipment remains protected, reliable, and focused on testing what matters.
#TrueRF #RFTesting #EngineeringBestPractice #RadioCommunication #LoadMatching #RFSafety #Sunscreen
22-AUG-2024
 Free 3D Printable SMA Connector Wheel from True RF!
A big shout out to all our mentors in radio electronics engineering for their wisdom over the years, especially their advice on taking care of our coaxial cable connectors. The life of radio frequency connectors can be extended by restricting movement to the securing thread, preventing the spin of the central conductors against each other.
An alternate approach is to use quick-connect type connectors. However, as the complexity and time to execute tests increase, the traditional mechanically secure nut approach is best. It is disappointing to find a loose connection during the disassembly of a test, placing doubt over results, and triggering a retest in the lab.
At True RF, weâve developed a handy SMA wheel tool to reduce human effort, time to make reliable connections, and prolong the life of equipment. It slides over your existing SMA connectors, with a small clip to hold it in place.
Download the STL format file or ask for some when we next meet.
We want to improve outcomes for everyone, and this is a simple way we can give back to the community. If this matches your values and interests, consider following True RF on LinkedIn.
Recommended 3D print settings: PLA filament, 100% infill.
Download Link:Â https://truerf.com.au/tools/TrueRF_SMA_Wheel_R6.stl