LF, MF, HF, VHF, and UHF signals and Walls

[Miss Amy]

How many walls does a HF signal has to go through before the signal starts to fade considerably? How about LF, MF, VHF, and UHF signals? From what I've read, lower frequencies go through more walls than higher frequencies before fading out, is that correct? Thanks a lot for reading this!

 

[DaveE]

You are correct that, in general, lower frequencies will be attenuated less. However, the amount of attenuation depends on how the walls are constructed. So I don't think there is a simple answer. Here's one link that discusses this, there are many others too.
https://www.dataloggerinc.com/wp-content/uploads/2016/11/16_Basics_of_signal_attenuation.pdf

 

[Baluncore]

How many walls does a HF signal has to go through before the signal starts to fade considerably?

Define 'fade considerably'.

Depending on materials and wavelength, the walls, floor and ceiling surfaces may take any combination of transparent, absorptive or reflective. Significant attenuation only occurs with some materials and some dimensions. Doors and windows may block or encourage propagation depending on material, size and wavelength.

A conductive copper sheet will be an excellent mirror at RF. But unless you completely close the box without gaps, the RF surface currents will pass around the boundaries at the edge of the wall.

So the answer to your question depends on why you ask such a general question.

 

[berkeman]

Methinks @Miss Amy is asking this because of her SDR project...

I'm talking about the HF range (30mhz-3mhz) and lower (since that is the range the KiwiSDR has). Unfortunately, I have to have the antenna inside my house and near my computer/internet connection. Would that be okay? Are general internet connestions HF and lower?

 

[Baluncore]

The KiwiSDR looks good for 10kHz to 30MHz, especially with the 14 bit A-D converter. But without an external antenna, I expect Miss Amy will be making a study of digital and switch-mode power supply noise in the HF band. Walls will not be the problem. Small external antennas are possible for RX.