MatchLab user manual
Everything you need to go from an antenna measurement or simulation file to a matching circuit you can build.
What MatchLab does
An antenna rarely works well straight out of its measurement: part of the power reflects back instead of radiating. A matching circuit (a few inductors and capacitors between the radio and the antenna) fixes that. MatchLab takes your antenna's S-parameters, tries thousands of circuit arrangements using real, catalogued parts (including their own losses), and ranks the best ones against the frequency bands you care about.
What you get back for every candidate: efficiency and S11 curves, a Smith chart, a verdict for each band, a full power-loss breakdown, a drawn schematic, live part tuning, a manufacturing-tolerance (yield) study and hand-off files for your simulator.
Quick start (5 steps)
- Data – load your antenna file (Touchstone
.s1p,.s2p…) or press “Load a demo antenna” to try it. - Targets – add the frequency bands the antenna must work in (pick presets, or type start and stop in MHz).
- Search – choose how many matching parts you allow, pick the parts library, and press Run search.
- Results – click a circuit in the ranked list. Check the band tiles, the curves and the schematic.
- Export – download the circuit, report and CST macro.
Use Next and Back at the bottom of each setup page, or the left menu.
1 · Data
Antenna file
Drop or choose a Touchstone file (.s1p for one port up to .s32p). The file holds S11 versus frequency measured or simulated at the antenna feed. A CST export .zip (S-parameters plus efficiency) also works.
Antenna efficiency (optional)
Without it MatchLab assumes the antenna itself is lossless, so results show the mismatch effect only. If you have the antenna's own radiation efficiency (CST or similar table, one file per port or a summary table, or far-field .ffd/.rpf files) add it here and tick Include antenna efficiency in all results – numbers then show real total efficiency.
Single-port or multiport
Single-port uses port 1 of the file. Multiport (a file with 2 or more ports) lets you give each port a role – see Multiport antennas.
2 · Targets
A band is a frequency range with a goal.
| Field | Meaning |
|---|---|
| Band start / stop (MHz) | The range to optimise. |
| Goal | Pass = maximise efficiency in this band. Stop = keep it quiet (used to avoid a band where you do not want to radiate). |
| Weight | How much this band matters relative to the others in the score (1 = normal, 2 = twice as important). |
| Eff ≥ (%) and S11 ≤ (dB) | Optional pass/fail targets. The result tile turns green when met, red when missed. |
| Judge targets by | Band average (typical) or worst point in the band (strict). |
Adding bands quickly
- Preset chips – tick several (Wi-Fi, Bluetooth, GPS, LTE…) and press Add selected bands.
- Add several bands from the library – opens the full list (GSM, WCDMA, LTE FDD/TDD, Wi-Fi, GNSS, ISM…). Click one, then Ctrl+click or Shift+click to select more, then Add selected bands.
- Type several at once – e.g.
824-894, 1710-1880, 2400-2483.5. - Fit sweep to bands – trims the analysed frequency range to your bands. The sweep box sets the range drawn on the charts.
- Saved band sets – save and reload your favourite band lists (kept in this browser only).
3 · Search
| Setting | Meaning |
|---|---|
| Number of parts | Maximum matching components. More parts can match more bands but add loss, cost and board area. Start with 2 or 3. |
| Search effort | Quick, Standard or Thorough – how hard it looks. Thorough takes longer. |
| Score domain | How efficiency is turned into a score. “dB (stricter)” punishes weak spots harder than “Linear”. |
| Weight within / across bands | Balance between the average and the weakest point, and between bands. |
| Prefer simpler circuits | Among circuits that score almost the same, favour the one with smaller values / fewer parts. |
| Parts library | Murata inductor and capacitor series with their tolerances and value ranges. You can also upload your own 2-port .s2p part files; these replace the library for this session only. |
Press Run search. A progress bar shows 0 – 100 % while MatchLab works. A search counts once against your allowance; tuning, tolerance runs and exports do not.
Reading the results
After the search the screen switches to the results workspace. The left menu now means: Results (main window), Tolerance, Export; Data / Targets / Search take you back to change the setup (then run again).
- Ranked circuits (left) – best first, with score and part values. Click one to select it.
- Band tiles – per band: average efficiency, the weakest efficiency, worst S11, and a green/red verdict against your targets.
- Efficiency, S11, Smith chart – shaded bands are your targets. Move the mouse over a curve to read frequency and value. Double-click a chart to place a marker; drag to move it.
- Where the power goes – for each band, how the power splits into radiated, reflected (mismatch), antenna loss, loading parts (loss in your matching components), feed network and coupling. Rows add up to 100 %.
- Circuit schematic – the selected network, with designators, values and part numbers.
- Edit setup / History / Compare – change the setup; see earlier runs in this session; compare the curves of several circuits side by side.
Good efficiency numbers
As a rule of thumb: above 60 % is good for a small antenna, 40–60 % is workable, below 30 % usually needs a better antenna or fewer constraints. S11 better than −6 dB is a useful match; −10 dB is a good one.
Tuning parts
The Tune the selected circuit card lists each part with a drop-down of neighbouring catalogue values and ◀ ▶ buttons. Change a value and the curves, tiles and score update immediately. The faded line is the original circuit. Reset to original undoes your changes. Exports always use the tuned values.
Tolerance (Monte Carlo yield)
Real parts vary (for example ±0.1 pF or ±2 %). Open Tolerance from the left menu to test how your circuit survives that. MatchLab builds many random versions of the circuit within the part tolerances and reports the yield: the share that still meets your condition.
- Trials – how many random circuits (300 is a good start).
- Distribution – uniform within tolerance, or Gaussian.
- Pass if band efficiency drops by no more than (dB) – the acceptance rule. Min. band efficiency is an optional extra rule.
- Tolerance for all parts – override the library tolerance.
- Seed – the same seed repeats the same random study.
Most users only need this before releasing a design to production. It does not use up a search.
Export
| File | Use |
|---|---|
| Download all (.zip) | Everything below in one zip. |
| Report (HTML) | A printable summary – open it and choose Print → Save as PDF. |
| Netlist (.cir) | SPICE-style netlist of the matching circuit. |
| CST schematic macro (.zip) | Extract it (e.g. to C:\MatchLab_CST\) and follow the README inside to build the circuit in CST's schematic, with the vendor part files included. |
| Touchstone (.s1p) | The matched S11 of the antenna plus circuit. |
| Parts list / Response (CSV) | Bill of materials and the curve data for Excel. |
The quick buttons are on the right of the main results window (Hand-off). The Export view in the left menu has every option.
Multiport antennas
For antennas with several feeds (MIMO, diversity) load a file with 2 or more ports and choose Multiport. Give each port a role: external (it gets its own matching network), a fixed termination (50 Ω, a load or a part), or left alone. Each band can be assigned to a specific feed. Results show one feed at a time – use the Port buttons above the schematic. Coupling between ports is included in the power-loss breakdown.
CST export macro
If you simulate in CST Studio Suite, you can avoid exporting files by hand. Download the MatchLab CST macro (also linked on the Data page). Install it once in CST (Macros → Make VBA Macro), run it on a finished project, and it saves <project>_MatchLab_bundle.zip in your Downloads folder with the S-parameters of all ports and the antenna efficiency. Drop that zip on the CST export bundle box. The zip includes step-by-step instructions.
New antenna, new bands, new search
After a search you can download what you need (report, CST macro, netlist, parts list) from the Hand-off panel. To continue:
- New bands, same antenna: press Targets in the left menu, change the bands, go to Search and press Run search. This is a new search.
- New antenna: go to Data and choose the new file (or CST bundle). The old results are cleared automatically, your band list and search settings are kept, and you can run again. No page refresh is needed.
- Everything from scratch: press Start over in the top bar.
If you have results that are not saved, MatchLab asks whether to save the project first before it clears anything. Closing or refreshing the page also warns you.
What counts as a search? Each press of Run search that finishes successfully counts as one search, whatever the number of bands or parts. A search that fails is not counted. Tuning parts, tolerance runs, downloads, reports and CST macro exports never count. Tip: add all the bands you care about before you run, so one search covers them.
Projects and searches
- Save project stores your setup and results; open it later from Saved projects. Saved projects are deleted automatically after 10 days.
- Your account has a number of searches (shown at the top). The administrator can increase it – contact info@ampnode.in.
- Only the person named on the account may use it. Do not share sign-in links.
Buying more searches
When your searches run low, press Buy searches in the top bar and choose a pack. We receive your request and email you the payment instructions. After you pay, reply to that email and we add the searches to your account; you will get a confirmation email. Tuning, tolerance runs and exports never use searches. For invoices or larger volumes write to info@ampnode.in.
Questions and answers
My efficiency looks too good to be true.
Check that you added the antenna efficiency file on the Data page. Without it the antenna is treated as lossless.
No circuit meets my targets.
Try allowing more parts, widening the library ranges, relaxing the targets, or searching fewer or narrower bands. The “Bandwidth potential” view (open it from All candidates / Bandwidth in the results menu) shows how wide a band an ideal lossless match could ever reach with your antenna.
Why do two circuits with the same score look different?
Many networks perform alike. Prefer the simpler one, or the one with the best tolerance yield.
The sign-in link does not work.
Links work once and expire. Request a new one from the sign-in page.
Who do I contact?
info@ampnode.in
Results are engineering estimates based on your data and the manufacturers' published part models; always verify on hardware. See the terms of use.