关于介电损耗

在看某高速pcb设计guideline的时候，讲到如何减少losses的时候，提到了两个方法，一个是使用大线宽（这个好理解）；还有一个是“use low dissipation factor laminate”，这个是啥意思，有人能解释下吗?

不过，他又提到线宽不是越宽越好：
If FR4 is the dielectric, the dissipation factor is about 0.02. Above 1 GHz, and line widths of about 8 mils, the losses are dominated by the dielectric, so there is not much gain going to a wider line than about 8 mils.

这句话如何理解，说增加线宽必要增加介质厚度来实现100欧匹配?
The only knob to affect conductor losses is the width of the conductor. To minimize conductor losses, use a wide conductor. Of course, at the same time we increase the line width, we will also have to increase the dielectric thickness to maintain our target differential impedance of roughly 100 ohms.

用耗损小的介质

意思是说你增加了线宽，为了保持阻抗不变，势必要增加介质层的厚度，这样介质损耗又增加了。