- #1
Tech2025
- 48
- 7
What I understand about harmonics, is when something is transmitted at high power, the antenna resonates on other frequencies besides the desired one. But Why?
We usually assume an antenna is linear - which is fine for a new one with no no rusty bolts.Tech2025 said:What I understand about harmonics, is when something is transmitted at high power, the antenna resonates on other frequencies besides the desired one. But Why?
Thanks for the explanation, Just getting started with learning antenna theory.sophiecentaur said:We usually assume an antenna is linear - which is fine for a new one with no no rusty bolts.
The non linear products come from the active devices in the transmitter amplifier. For the sake of efficiency, most transmitter designs will have some compromise with regard to the linearity so there will be some inherent harmonic content.
Back to the antenna. It is unlikely that an antenna will happen to 'resonate' at an exact harmonic of the fundamental of the transmitted signal but you don't need resonance for a piece of metal to radiate. Harmonics will tend to get through if you do not filter them out somewhere along the chain. The regulations are pretty severe about out of band radiation and, in addition to limits on radiated harmonic levels, other non linear products such as the theoretically infinite sidebands of an FM signal may also be radiated.
It is worth asking you what your level of knowledge of this very nerdy topic and how deep you want to delve.
I edited my post and added a bit.Tech2025 said:Thanks for the explanation, Just getting started with learning antenna theory.
Radio transmission harmonics are unwanted frequencies that occur at integer multiples of the fundamental frequency in a radio signal. They are caused by nonlinearities in the radio transmission system.
Harmonics occur because of nonlinearities in the radio transmission system. These nonlinearities can be caused by imperfections in the components or by external factors such as interference.
Harmonics can cause interference with other radio signals and result in degraded signal quality. They can also cause distortion and false reception of signals, leading to errors in data transmission.
While it is not possible to completely prevent harmonics, they can be minimized through proper design and maintenance of radio transmission systems. This includes using quality components and shielding, as well as regularly testing and calibrating the system.
Harmonics can be detected and measured using spectrum analyzers, which display the frequency components of a signal. They can also be detected using specialized filters and probes that are designed to isolate and measure specific harmonics.