The higher the frequency of the RF cable assembly, the more difficult it is to design and build, and the higher the cost of RF cable assembly manufacturers, which means that buyers need to purchase at a higher cost. What is the reason?
This can be attributed to the laws of physics and Maxwell's equations. At these higher frequencies, any theoretical deviation is a detrimental factor, even if it is very small. Higher frequencies mean shorter wavelengths, so the cable size is smaller, so the tolerances must be tighter than the dimensions. Some multi-GHz cables are now only a few millimeters in diameter and ten times smaller than low-frequency cables. This situation is exacerbating, and many of these cables need to be mechanically robust.
In some of the highest performance applications, subtle changes in cable parameters due to bending, temperature changes, and other "normal" changes will result in reduced performance. Some vendors offer specially designed and manufactured cables to withstand these changes at a price; in other cases, such as phased array radar systems, cables must be plugged in and out to track and change with temperature.