very-high frequency band

Its difficult to maintain the multi-band receiver because of its wide frequency range and high integration, for which the usual intelligent detector is very complex.

多波段接收机覆盖频段宽，集成度高，维修保障难度大，采用智能故障诊断时的结构复杂，文章介绍的故障层次分类结构可大大提高智能诊断系统的工作效率。

The fast wave device gyrotron is base on the radiation theory which is excitated by electrons cyclotron resonance. Its frequency is very high especially at the millimeter and sub-millimeter wave band.

回旋管是一类基于电子回旋谐振受激辐射机理的快波器件，工作频率范围宽，特别是在毫米和亚毫米波段，能产生高脉冲峰值功率与连续波功率。