功率衰减器是一种能量损耗性射频/微波元件,元件内部含有电阻性材料。除了常用的电阻性固定衰减器外,还有电控快速调整衰减器。衰减器广泛使用于需要功率电平调整的各种场合。一、衰减器的技术指标衰减器的技术指标包括衰减器的工作频带、衰减量、功率容量、回波损耗等。1、工作频带。衰减器的工作频带是指在给定频率范围内使用衰减器,衰减器才能达到指标值。由于射频/微波结构与频率有关,不同频段的元器件,结构不同,也不能通用。现代同轴结构的衰减器使用的工作频带相当宽,设计或使用中要加以注意。2、衰减量。无论形成功率衰减的机理和具体结构如何,总是可以用下图所示的两端口网络来描述衰减器。 信号输入端的功率为P1,而输出端得功率为P2,衰减器的功率衰减量为A(dB)。若P1 、P2 以分贝毫瓦(dBm)表示,则两端功率间的关系为P2(dBm)= P1(dBm)- A(dB)可以看出,衰减量描述功率通过衰减器后功率的变小程度。衰减量的大小由构成衰减器的材料和结构确定。衰减量用分贝作单位,便于整机指标计算。3、功率容量。衰减器是一种能量消耗元件,功率消耗后变成热量。可以想象,材料结构确定后,衰减器的功率容量就确定了。如果让衰减器承受的功率超过这个极限值,衰减器就会被烧毁。设计和使用时,必须明确功率容量。4、回拨损耗。回拨损耗就是衰减器的驻波比,要求衰减器两端的输入输出驻波比应尽可能小。我们希望的衰减器是一个功率消耗元件,不能对两端电路有影响,也就是说,与两端电路都是匹配的。设计衰减器时要考虑这一因素。二、衰减器的基本构成构成射频/微波功率衰减器的基本材料是电阻性材料。通常的电阻是衰减器的一种基本形式,由此形成的电阻衰减器网络就是集总参数衰减器。通过一定的工艺把电阻材料放置到不同波段的射频/微波电路结构中就形成了相应频率的衰减器。如果是大功率衰减器,体积肯定要加大,关键就是散热设计。随着现代电子技术的发展,在许多场合要用到快速调整衰减器。这种衰减器通常有两种实现方式,一是半导体小功率快调衰减器,如PIN管或FET单片集成衰减器;二是开关控制的电阻衰减网络,开关可以是电子开关,也可以是射频继电器。三、衰减器的主要用途衰减器有以下基本用途:1、控制功率电平:在微波超外差接收机中对本振输出功率进行控制,获得最佳噪声系数和变频损耗,达到最佳接收效果。在微波接收机中,实现自动增益控制,改善动态范围。2、去耦元件:作为振荡器与负载之间的去耦合元件。3、相对标准:作为比较功率电平的相对标准。4、用于雷达抗干扰中的跳变衰减器:是一种衰减量能突变的可变衰减器,平时不引入衰减,遇到外界干扰时,突然加大衰减。从微波网络观点看,衰减器是一个二端口有耗微波网络。它属于通过型微波元件。英文:Power attenuator is a kind of energy loss of the RF / microwave components, devices with resistive material inside. Addition to the usual fixed resistive attenuator, there are electronically controlled attenuator to adjust fast. Attenuators are widely used in the power level needed to adjust a variety of occasions.First, the technical indicators attenuatorTechnical indicators include attenuator attenuator's frequency band, attenuation, power capacity, return loss and so on.1, the working frequency band. Attenuator is defined frequency band used within a given frequency attenuator attenuator to achieve the target value. Since the RF / microwave structures with frequency, the components of different frequency bands, different structure, it can not be universal. Modern coaxial attenuator used in a wide frequency band, design, or use it should be noted.2, the attenuation. Whether the mechanism of the formation of power attenuation and specific structure of how, can always shown below to describe the two-port network attenuator.Signal input power P1, the power output was P2, the power attenuation attenuator is A (dB). If P1, P2 in dB milliwatts (dBm) said that the two ends of the power relationship betweenP2 (dBm) = P1 (dBm) - A (dB)Can be seen that attenuation describes the power attenuator after the power through smaller degree. The size of attenuation by the attenuator material composition and structure determined. Attenuation in decibels as a unit, easy to machine index calculation.3, the power capacity. Attenuator is a component of energy consumption, power consumption, which becomes heat. Conceivable material structure determined, the power attenuator to determine the capacity. If you let the power attenuator to withstand more than this limit, the attenuator will be burned. Design and use, must be clear power capacity.4, back losses. Reversal of loss is the VSWR attenuator, attenuator required input and output VSWR at both ends should be as small as possible. We hope that the attenuator is a power consumption of components, can not affect both ends of the circuit, that is, with both ends of the circuit are matched. To be considered when designing the attenuator factor.Second, the basic component attenuatorConstitute the RF / microwave power attenuator is a resistive material base material. Usually the resistance is a basic form of attenuator, the resulting resistor attenuator network is lumped attenuator. Through a certain process to be placed to a different band resistance materials of RF / microwave circuit structure to form the corresponding frequency attenuator. If the high-power attenuator and volume must be increased, thermal design is the key. With modern electronic technology, in many cases to use to quickly adjust the attenuator. The attenuator is usually implemented in two ways, first low-power fast transfer of semiconductor attenuatorSuch as tube or FET monolithic integrated PIN attenuator; the second is the resistance of attenuation of the network switch, the switch can be electronic switches, can also be a radio relay.Third, the primary purpose attenuatorAttenuator has the following basic purposes:1, control power levels: in the microwave superheterodyne receiver output power of the vibration control, the best noise figure and conversion loss, the best reception. In the microwave receiver, automatic gain control, improved dynamic range.2, decoupling components: as the oscillator and the load to the coupling between the components.3, the relative standard: as a comparison of the relative standard power level.4, for radar jamming transition in the attenuator: a mutation of attenuation can be variable attenuator, usually without introducing attenuation, encountered outside interference, the sudden increase attenuation.Microwave network from the point of view, is a two-port attenuator lossy microwave networks. It is through the type of microwave components.