A stub acts as a reactive component, providing either capacitive or inductive reactance depending on its physical length relative to the signal wavelength and whether its far end is open or short-circuited. Radio frequency engineers place them along waveguides or microstrip lines to cancel out reactive mismatches and maximize power transfer. They are physically etched into printed circuit boards or attached as coaxial segments.
We need to add an open-circuit stub right at the antenna feed point to tune out that extra capacitance.
Related terms
PCB
A laminated board holding and connecting electronic components using conductive traces.
Return path
The route that electrical current takes to flow back to its source, completing a circuit.
Impedance coil
A wire coil specifically designed to introduce a set amount of impedance to an alternating current circuit.