高频电子设备机壳散热孔电磁辐射特性分析

Analysis of EM Radiation Characteristics at Louvers on HF Electronic Equipment Enclosures with Apertures

随着高频电子设备的增多和布局越来越密集,为使设备间能够互不干扰的正常工作,兼顾设备的散热性和电磁兼容性就成了一个非常突出的问题。该文从高频电子设备机壳散热孔的辐射场入手,对机壳上所常开的矩形孔、圆形孔的辐射场采用解析法进行了分析计算,并对二者的辐射场进行了分析比较,在电子设备机箱上开散热孔,若已知外来电磁波频率,即波长一定时,所开的矩形孔的宽边尺寸应控制在w≤0.1λ以下,矩形缝隙的尺寸越小越好,且缝隙的长宽比l/w越大越好。在开孔面积相同的条件下,圆形孔的辐射比矩形孔的辐射要小,所以尽量开圆形散热孔,且孔的直径尽量控制在2a≤0.1λ以下,此时孔的辐射比较小,对外部设备及对内部电路的影响比较小。

In order to enable equipments to be noninterference in each other＇s normal work among equip- ments, consideration must be given to both the heat dissipation of equipments and the electromagnetic compatibility of equipments with the increase of HF electronic equipments and their dense distribution. This paper analyzes and calculates the radiation fields of the louver of HF electronic equipments, the com- mon rectangular and circular louver＇s radiation field by analytical method, and then compares the both field results. Under condition that louvers are made in HF electronic equipments, and the outcome electromag- netic wave＇s frequency is known, i.e. the wavelength is constant, the width of rectangular louver should be less than or equal to 0.1X, and the smaller the size of rectangular louver, the better the its performance, and the bigger the length--width ratio, the better the its performance. In the condition of same area of lou- ver, the radiation fields of circular louver are smaller than that of rectangular one. The best way is to make a circular louver, and the diameter of a louver should be less than or equal to 0.1λ as far as possible. In this case the radiation field of louver is the smallest, and its influence on external equipments and internal cir- cuits is comparatively weak.