🔍 Key Concepts

• Resonant frequency of an antenna and how it relates to antenna electrical length • Effect of adding inductive reactance (L) vs capacitive reactance (C) in series with an antenna • How a Marconi (quarter‑wave vertical) antenna behaves when it is physically too short for the desired lower frequency

💭 Think About

• Think about whether you want the antenna to behave as if it is electrically longer or shorter to reach a lower frequency. • For a physically short vertical antenna, does it tend to look more capacitive or inductive, and what component in series would you add to cancel that reactance? • Which choice actually changes the series reactance of the radiating element, as opposed to just providing a bypass or a choke path elsewhere in the circuit?

✅ Before You Answer

• Identify which options place a component in series with the antenna element itself (those are the only ones that can directly change its resonant frequency). • Recall that to lower resonant frequency you must make the antenna electrically longer, and ask which component in series has that effect. • Eliminate any options that mostly deal with bypassing RF to ground or decoupling rather than tuning the antenna’s natural resonance.