diff --git a/docs/hardware/antennas/testing.mdx b/docs/hardware/antennas/testing.mdx
index 39ec6f8b..12e8d97d 100644
--- a/docs/hardware/antennas/testing.mdx
+++ b/docs/hardware/antennas/testing.mdx
@@ -80,7 +80,7 @@ Unless you're using your devices in a vacuum, with clear line of sight between a
 For a bit of light reading on environmental research:
 
 - [RF attenuation in vegetation](https://web.archive.org/web/20201216041455/https://www.itu.int/dms_pubrec/itu-r/rec/p/R-REC-P.833-9-201609-I!!PDF-E.pdf) (yes really); if you wander through the woods wondering how your RF is bouncing off leaves dependent on their variety, and wind speed … well you do, now.
-- [RF attenuation with various building materials](https://www.ofcom.org.uk/__data/assets/pdf_file/0016/84022/building_materials_and_propagation.pdf).
+- [RF attenuation with various building materials](https://web.archive.org/web/20230606172231/https://www.ofcom.org.uk/__data/assets/pdf_file/0016/84022/building_materials_and_propagation.pdf).
 - This one by ITU again is very detailed in its [analysis of the drivers of attenuation](https://web.archive.org/web/20211005174833/https://www.itu.int/dms_pubrec/itu-r/rec/p/R-REC-P.2040-1-201507-I!!PDF-E.pdf) (I wasn’t aware that all EMF radiation exhibits reflection / transmission characteristics akin to light hitting a material boundary. So, depending on the angle of incidence, material and the EMF wavelength, it will be reflected and / or transmitted through).
 - These RF bands are also made more [noisy by adjacent LTE](https://www.ofcom.org.uk/__data/assets/pdf_file/0023/55922/lte-coexistence.pdf)