Every once in a while, I answer amateur radio questions on Quora, and sometimes I get requests to answer them. Well, a request popped up in my inbox this morning, and I just clicked on the link. I got a real chuckle from the two replies (see below)….Dan
Does a resonant antenna work better than a non-resonant antenna?
Reply #1 from “Retired EE with aerospace and biomedical experience & 8 patents.”
Yes a resonant antenna properly matched to the transmitter or reciever will work better a non-resonant antenna. Any antenna discussion MUST include the frequency or frequency band in order to be more detailed.Reply #2 from “Physicist, Electronic Engineer, Musician (1968-present)”
No. It may be easier to match a feedline to it, but once a current distribution is achieved in it, it radiates just as well as a non-resonant dipole.
So, antenna gurus, which one do you think is right?
UPDATE 6/14/20
A third fellow replied:
In order to avoid confusion, I offer a definition of a resonant antenna. (First of all, I am assuming you are not referring to an uncommon antenna type that has no resonance, no standing wave.) Irrespective of the feedline characteristics (assuming there is a feedline—could be fed directly by equipment), at its feed point, an antenna presents a certain impedance value as a function of frequency. The frequency for which this impedance is resistive (contains no reactive component) is the resonant frequency.
The objective when feeding an antenna is to transfer as much power as possible to it. As with any type of load, this is accomplished when the source and load impedance values are “matched”. Following from the previous paragraph, a resonant antenna needs to be fed with source having a resistive impedance equal to that presented by the antenna.
At all frequencies other than its resonant frequency the antenna presents a reactive impedance component (inductive or capacitive) that adds to the resistive component. If the source impedance is still resistive, it is no longer matched to that of the antenna, so the power delivered to it is reduced. In other words, any series reactance of the antenna adds to the resistive (called radiation resistance) component to reduce the amount of current flow; so the antenna does not work as well.
This does not mean, however, that a non-resonant antenna cannot work as well. If the source impedance is adjusted to add reactance that is equal and opposite to that presented by the non-resonant antenna, the power delivered to it will equal that of the antenna’s resonant frequency. A properly impedance “matched” non-resonant antenna works (radiates) just as well as a properly matched resonant antenna.
The equipment used to maintain this impedance “match” over a relatively wide frequency range is called an Antenna Tuner. Inasmuch as mounting and adjusting an antenna tuner attached/connected directly to the antenna feed point is normally frightfully awkward, it is normally at the radio equipment end of the feedline. In this configuration, the feedline and antenna are automatically tuned simultaneously. There are implications for the most desirable type of feedline to use, but that is another discussion.
(Note: As the frequency is changed, the resistive portion of antenna feed point impedance varies as well, but this change is relatively minor and is also compensated for by the antenna tuner.)
I like this answer.