In amateur radio, we care about impedance matching when we need to keep the load within the equipment's specification (for best performance, or just to avoid damaging a transmitter), when we want to maximize the power delivered into the load, or when a minimum noise figure is desiable.

When the reasons above are not a concern, impedance matching can be ignored. For example, in the question What is the relationship between SWR and receive performance, Phil Frost answered that "There is no relationship between SWR and receive performance". Surely, modern electronics have a lot of gain, and on HF, the inherit noise from the environment is often already much greater than noise floor of the radio receiver, as long as the SNR is reasonable, a HF receiver will happily receive everything coupled into it, even a random wire works, in this case, matching is pointless or sometimes counterproductive.

Nevertheless, they are not the only reasons for wanting a matched impedance or low SWR. In video engineering and high-speed digital systems, impedance termination (often by a resistor) is usually mandatory, even if it decreases the power delivered into the load, because of another reason: the reflection on the transmission line causes signal distortion. In analog video, the reflection causes "ghosting" on a TV screen. In digital systems, the reflection causes intersymbol interference that increases the error rate of the transmission, or creates unacceptable overshoot and ringing.

However, I don't see this issue discussed by any amateur radio publication. Why?

I assume it's not important, either because it's

1. Only relevant for higher-frequency signals above HF. Within HF, the wavelength is long, so these adversary transmission line effects don't show up.

2. It's only the case for high speed, wide bandwidth (a few megahertz or more) signals. On HF, bandwidth of a signal is measured in kilohertz. We never use wide-bandwidth signal on HF.

But I'm not sure which one is the case.

In amateur radio, we care about impedance matching when we need to keep the load within the equipment's specification (for best performance, or just to avoid damaging a transmitter), when we want to maximize the power delivered into the load, or when a minimum noise figure is desiable.

When the reasons above are not a concern, impedance matching can be ignored. For example, in the question What is the relationship between SWR and receive performance, Phil Frost answered that "There is no relationship between SWR and receive performance". Surely, modern electronics have a lot of gain, and on HF, the inherent noise from the environment is often already much greater than noise floor of the radio receiver, as long as the SNR is reasonable, a HF receiver will happily receive everything coupled into it, even a random wire works, in this case, matching is pointless or sometimes counterproductive.

Nevertheless, they are not the only reasons for wanting a matched impedance or low SWR. In video engineering and high-speed digital systems, impedance termination (often by a resistor) is usually mandatory, even if it decreases the power delivered into the load, because of another reason: the reflection on the transmission line causes signal distortion. In analog video, the reflection causes "ghosting" on a TV screen. In digital systems, the reflection causes intersymbol interference that increases the error rate of the transmission, or creates unacceptable overshoot and ringing.

However, I don't see this issue discussed by any amateur radio publication. Why?

I assume it's not important, either because it's

1. Only relevant for higher-frequency signals above HF. Within HF, the wavelength is long, so these adversary transmission line effects don't show up.

2. It's only the case for high speed, wide bandwidth (a few megahertz or more) signals. On HF, bandwidth of a signal is measured in kilohertz. We never use wide-bandwidth signal on HF.

But I'm not sure which one is the case.

In amateur radio, we care about impedance matching when we need to keep the load within the equipment's specification (for best performance, or just to avoid damaging a transmitter), when we want to maximize the power delivered into the load, or when a minimum noise figure is desiable.

When the reasons above are not a concern, impedance matching can be ignored. For example, in the question What is the relationship between SWR and receive performance, Phil Frost answered that "There is no relationship between SWR and receive performance". Surely, modern electronics have a lot of gain, and on HF, the inherit noise from the environment is often already much greater than noise floor of the radio receiver, as long as the SNR is reasonable, a HF receiver will happily receive everything coupled into it, even a random wire works, in this case, matching is pointless or sometimes counterproductive.

Nevertheless, they are not the only reasons for wanting a matched impedance or low SWR. In video engineering and high-speed digital systems, impedance termination (often by a resistor) is usually mandatory, even if it decreases the power delivered into the load, because of another reason: the reflection on the transmission line causes signal distortion. In analog video, the reflection causes "ghosting" on a TV screen. In digital systems, the reflection causes intersymbol interference that increases the error rate of the transmission, or creates unacceptable overshoot and ringing.

However, I don't see this issue discussed by any amateur radio publication. Why?

I assume it's not important, either because it's

1. Only relevant for high-speed signals above HF. Within HF, the wavelength is long, so these adversary transmission line effects don't show up.

2. It's only the case for high speed, wide bandwidth (a few megahertz or more) signals. We never use signal of this type on HF.

But I'm not sure which one is the case.

In amateur radio, we care about impedance matching when we need to keep the load within the equipment's specification (for best performance, or just to avoid damaging a transmitter), when we want to maximize the power delivered into the load, or when a minimum noise figure is desiable.

When the reasons above are not a concern, impedance matching can be ignored. For example, in the question What is the relationship between SWR and receive performance, Phil Frost answered that "There is no relationship between SWR and receive performance". Surely, modern electronics have a lot of gain, and on HF, the inherit noise from the environment is often already much greater than noise floor of the radio receiver, as long as the SNR is reasonable, a HF receiver will happily receive everything coupled into it, even a random wire works, in this case, matching is pointless or sometimes counterproductive.

Nevertheless, they are not the only reasons for wanting a matched impedance or low SWR. In video engineering and high-speed digital systems, impedance termination (often by a resistor) is usually mandatory, even if it decreases the power delivered into the load, because of another reason: the reflection on the transmission line causes signal distortion. In analog video, the reflection causes "ghosting" on a TV screen. In digital systems, the reflection causes intersymbol interference that increases the error rate of the transmission, or creates unacceptable overshoot and ringing.

However, I don't see this issue discussed by any amateur radio publication. Why?

I assume it's not important, either because it's

1. Only relevant for higher-frequency signals above HF. Within HF, the wavelength is long, so these adversary transmission line effects don't show up.

2. It's only the case for high speed, wide bandwidth (a few megahertz or more) signals. On HF, bandwidth of a signal is measured in kilohertz. We never use wide-bandwidth signal on HF.

But I'm not sure which one is the case.