Radiation shield

A radiation shield is a device that serves to protect and place meteorological sensors, most often temperature and humidity sensors. Its main task is to protect the sensors from environmental influences that could distort the measured values.

• Direct sunlight: Heats the sensor above ambient temperature, resulting in falsely high readings.
• Precipitation: Rain and snow can wet the sensor and affect its functionality.
• Wind: Can cool the sensor and lead to underestimated values.
• Thermal conductivity: Contact with surrounding objects can lead to heat transfer and measurement distortion.

Parts

It consists of four types of individual parts, and the height can be modulated. Basic parts have 22mm height and diameters 112mm. Each piece has opposing surfaces for stacking. The slope of the radiation shield slats is 75 degrees. The slats protect the inner circuit board from water, splashes and drips.
The measuring well has a diameter of 40 mm The holder and the pass-through part have a groove (44 x 3mm) for inserting the PCB with the sensors.

Holder

The holder is a part for attaching the radiation shield to a pipe with a diameter of 40 mm. Cable ties or stainless steel hose clips can be used for attachment. Hole for attachment have 15 x 5 mm. 
On the bottom of this part there are two threaded inserts M3 x 5 mm, which are used to arrest the PCB in the radiation shield

Through part

The through part extends the radiation shield to the required height.

Separator

The separator extends the distance and isolates the top cover from the measuring well. It prevents heat from passing through the top of the radiation shield.

Top cover

The top cover has four holes for M4 x 5 mm threaded inserts. Threaded rods for mounting the radiation shield are screwed into these inserts.

Printing

The radiation shield is printed from white PET-G, which is resistant to UV radiation. Cubic 15% infil is used to minimize heat transfer from the shell surface. These settings prevent the internal passage of heat through the material. Recommended printed with support.

Assembly

Four M4 threaded rods are used for assembly, which are screwed into the upper cover part. Then the individual parts of the radiation shield are gradually inserted. The length is variable according to the number of parts used.
After assembling the radiation shield, M4 domed cap nuts are screwed onto the threaded rods.

Ideal location for measurements

According to metrological information, the radiation shield should be placed at a height of 2 m above the ground. It is also placed on a grass surface with a maximum grass length of up to 25 cm. Furthermore, it is located at a sufficient distance from radiating surfaces, e.g. the facade of a house.

Testing

I have radiation shield on grass in my garden. The shield was tested in air temperatures of 30 degrees.

Shoots from thermocam, afer instalataion. Surface have 29.2 degrese. (The warm spot is a dark photovoltaic panel)	Shoots from thermocam, afer instalataion. PCB in measuring well have 29.4 degrese. (The warm spot is a dark photovoltaic panel)
Shoots from thermocam, after 3 hours. Average air temperature is 33 degrese. Surface have 33,1 degrese.	Shoots from thermocam, afer 3 hours. PCB in measuring well have 33.4 degrese.

expLORA METEO
(Update - 1.6.2025) I inserted the measuring board from the expLORA METEO weather station into my radiation shield. After modifying the battery holder, the measuring PCB fits nicely into the radiation shield. [https://pajenicko.cz/meteorologicka-stanice-explora-meteo](https://pajenicko.cz/meteorologicka-stanice-explora-meteo)
I removed the original radiation shield.	PCB in radiation shield.	The batteries are removed, and the weather station is powered by a solar panel with a battery.