Specification:

- Condition: 100% brand new and high quality
- Item Name: SWR Bridge
- Color: as shown
- Frequency: spare parts: 1.8M-30MHz; finished product: 3.5-30MHz (default)
- Size: 45mmX 29mm
- Type:
A: DIY Kit (optional)
B: Finished board

10-3000MHz Standing Wave Ratio Reflection Bridge SWR RF Directional Bridge Network Circuit Antenna Ham Radio Amplifier
https://www.banggood.com/10-3000MHz-Standing-Wave-Ratio-Reflection-Bridge-SWR-RF-Directional-Bridge-Network-Circuit-Antenna-Ham-Radio-Amplifier-p-1789895.html?currency=EUR&utm_source=criteo&utm_medium=cpc_brand&utm_content=all&utm_campaign=electronics-emea-en&cur_warehouse=CN

Model: Standing wave bridge
Frequency range: 1MHz ~ 3GHz (1MHZ-2.6GHZ is relatively flat)
Characteristic impedance: 50Ω
Directionality: ≥30dB
Maximum input power: ≤0.2W

https://transverters-store.com/rf_bridge/rf_bridge.html

If you got bridge from China 99,9% chance it is a fake and not working due to serious errors in copying and bad ferrites. Luckily for you, errors can be easily fixed, but for 3GHz operation you´ll still have to replace coaxial cables with UT-141 rigid or something similar and replace ferrites with better. Fixed chinese fake can be used up to 1GHz.

You can also use one TinySa to measure and a noise source or RF generator. This will only work as a scalar analyzer and not as a vector analyzer so you can only measure SWR, Return Loss and impedance magnitude.

You need to calibrate using short, open and 50 ohm loads. Accuracy will be worse than a NanoVNA.