Antenna-Radome Distance: Understanding Optimal Spacing

Let’s explore the relationship between antennas and radomes, focusing on the crucial aspect of optimal distance for minimizing interference.

What is an Antenna Radome?

A radome is a protective enclosure designed to shield an antenna from harsh environmental conditions. Crucially, it’s made of a material transparent to electromagnetic (EM) waves, allowing the antenna to operate effectively without significant signal degradation.

Horn Antenna Radome

Parabolic Antenna Radome

The figures above illustrate examples of radomes used with horn and parabolic antennas.

Radome Thickness Calculation

The radome itself needs to be of a specific thickness to ensure minimal signal reflection and interference. The following formula is used to determine the appropriate thickness:

Radome thickness calculation formula

Optimal Distance: Minimizing Reflections

So, what’s the ideal distance between the antenna and the radome?

distance between antenna and radome

The key is to minimize the effects of reflections caused by the radome. These reflections can interfere with the antenna’s signal. The optimal distance is achieved when the reflected waves returning to the antenna are in phase with the transmitted waves. This minimizes destructive interference and maximizes signal strength. The formula for calculating this optimal distance is shown in the image above.

Example Calculation

Let’s consider an example:

For a carrier frequency (Fc) of 24.125 GHz, the wavelength (λ0) is approximately 12.4 mm. Using the formula in the image for distance between antenna and radome , we can get optimal distance i.e. dm.

$dm = λ0/2$

$dm = 12.4 mm/2 = 6.2 mm$

This gives us a dm of 6.2 mm.

• Distances < 6.2 mm should be avoided. These distances are more likely to cause significant interference due to out-of-phase reflections.
• Distances > 6.2 mm are not as critical. While still important to consider, the impact of reflections is less pronounced at larger distances.