30 September 2019
A simple guide to impedance matching for RF
23 September 2019
If PCB board design itself is highly complex, impedance matching is a dark art. With all the time and expertise that go into finalising a design; ensuring antenna impedance is correctly matched to source impedance can be daunting, especially when faced with complicated equations and a Smith chart – pictured below.
The traditional Smith Chart method requires a comprehensive understanding of the principles of RF, and involves a variety of steps. When designing very small devices, that require feed lines to navigate tight spaces and multiple components; the Smith chart method can prove challenging.
A Smith chart performs a necessary step in calculating the matching component values of your device. Calculating the impedance of an antenna, while vital to the effective operation of a wireless device, needn’t be so challenging. Impedance continuity allows an antenna to radiate at the intended frequency with minimal deviation, vastly increasing a devices performance capabilities.
An unmatched antenna will suffer a significantly reduced range and may render the device unable to operate effectively. This can cause issues such as reduced battery performance, poorer load speeds, or lack of signal.
If your device is defective due to an antenna impedance miscalculation, the manufacturing process can be greatly delayed; leading to unanticipated costs, lengthy redesigns and even entire product recalls.
For effective impedance matching, it is necessary to alter your transmission line dimensions. Beneficial, is to utilise grounded coplanar waveguide transmission lines. This is because their dimensions - including the width and the gaps between the feed lines conductors, as well as their height - can be altered to ensure impedance continuity between the antenna and its source.
Additional benefits to using GCPW feed lines include:
Due to the additional feed track dimensions, matching impedances via GPCW feed lines is a complex process. At Antenova, we recommend using our new free impedance matching calculator as it enables designers to quickly calculate the optimum dimensions of their transmission line to ensure efficient performance.
Antenova’s new tool is designed to be easy-to-use, and calculate dimensions quickly and accurately. With greater speed and accuracy, designers are able to tune the dimensional characteristics of any feed line without having to compromise on the PCBs design.
To use our transmission lines calculator effectively, follow the instructions below:
With all the possible options mapped out, the designer has the flexibility they require to ensure feed line dimensions match the source and load impedances, while being best-suited to their PCB board design.
For designers, working to get very complex PCB boards ready for that all important testing stage, this free and easy-to-use tool is hugely liberating. It takes the stress and risk out of a process that can otherwise be time-consuming and complicated. That means one less thing to worry about, and peace of mind when it comes to calculating antenna impedance. In doing this, the calculator helps ensure that your device performs as it should, and receives the full benefit of any chosen antenna.