Picking up from where Part 1 left off, this article explores the single-element, rectangular microstrip antenna. Antenna arrays will be examined later in the series.
Microstrip Antenna Feed Line
The resonant input resistance at the edge of the microstrip conductor is generally greater than the feed-line characteristic impedance and requires an impedance-matching structure to reduce the mismatch loss and thereby improve the antenna efficiency. Two common feed-line techniques can facilitate the impedance matching required to achieve an efficient rectangular microstrip antenna (Fig. 1).
1. Shown are the inset-feed (left) and quarter-wavelength (right) techniques for impedance matching.