平面域 meaning in English

plane domain

The creation of the concept of the definite integral was motivated by the problem of calculating the areas of certain plane regions .
定积分概念的产生是由求一个平面域的面积问题而导致的。
" modulation domain " ( mod ) is a plane domain which is consisted of frequency and time of signals . it is a necessary field to measure signals in three - dimension space of signal ( time domain , frequency domain and modulation domain )
调制域是由信号的时间和频率两个轴构成的平面域，是对信号进行三维(时域、频域、调制域)测量不可缺少的一个测试域。