USB 功率计的推出打破了人们对功率计为台式且体积庞大的印象。得益于半导体的快速发展，也得益于测试厂商的努力，便携小巧的功率计几乎一夜之间就如雨后春笋般冒了出来。这里列举了6个厂商的产品加以对比，相信对需要野外作业，以及非实验室环境下进行功率测试的工作者提供了极大的便利，并摆脱了台式功率计的束缚。
1. Keithley 3500 USD 1,500
2. Agilent U2000 USD 3,707
3. NI USB-5680 RMB 21,305
4. Boonton 52000 USD 1,785
5. Satori ST265 GBP 1,450
6. LadyBug LB480A USD1,745
Keithley 3500

  

Keithley在2006年推出的3500手持式功率计是我所见过的最小的RF功率计。初看上去外表有点像万用表，显得小巧精致。但在小巧的外观里仍然保持了实验室级的性能，提供了10MHz~6GHz的频率范围内20dBm~-63dBm的功率测量，内置了功率传感器，不需外接功率探头，内部自校准，提供了线缆插损补偿，并提供±0.21dB的绝对精度。3500是唯一一款本次对比中不需要电脑而能独立运行的功率计，用户可以选择2AA电池供电，交流供电，以及直接由USB供电，不过USB接口是USB2.0 full speed。软件编程支持XXXXXt,VB,VC，但没有独立的软件界面，这也是本次对比中唯一没有独立软件的功率计。
Agilent U2000

U2000A

U2000A block
Agilent 在功率计领域一直都是主要玩家之一，2007也推出了独立的USB功率计U2000系列，首次摆脱了功率探头。支持9kHz~24GHz频率范围，功率测量范围-60dBm~44dBm，具有内部调零，以及最快250次/s的测量速度。秉承了Agilent功率计的优良传统，U2000可与PC或Agilent的其它射频仪器无缝集成。并提供了内部触发，最多看支持到10通道。并支持Agilent富有盛名的功率分析软件N1918A，N918A-100，提供PDF，CDF，CCDF的统计分析功能，以及多达15项的脉冲测量。

Pulse test

CCDF
NI USB-5680

NI于2007年也推出了USB功率计USB-5680，补齐了射频产品线。该功率计的频率范围为50MHz~6GHz，功率测量支持-40dBm~23dBm,并提供了10Hz和100Hz两种典型通道带宽。功率小于0.18dBm是提供0.13dB的绝对精度，具备内部调零。该功率计支持CW真有效值功率测量，除了提供labview的独立软件外，IVI驱动可以和自家产品Labview，Labwindow/CVI无缝集成，并支持 .NET,C,C++。

5680 Fornt Panel

5680 Labview example
Boonton 52000和Satori ST265


Boonton 52000

Satori ST265
鉴于这两款产品相似的外观，相同的规格，相信是出自一个团队之手，只是由两家公司各自生产。
虽然Satori Technology名不见经传，但Boonton却是以功率计而闻名于世。Boonton以52000系列冠名，而Satori则是ST124，ST185，ST265对应。总之这种USB功率计提供10MHz~26.5GHz的频率范围，以及20~-50dBm的功率测量范围，8~50次/S的测量速度，同NI的USB-5680一样，只支持CW信号。12.4GHz和18.5GHz的连接头为SMA，26.5GHz的连接头为K型。

软件界面
关于Satori Technology
Satori Technology designs and develops powerful USB-based RF sensors that are controlled by easy to use software. The company, based in Scotland, has a dedicated and experienced team of highly motivated engineers with many years of knowledge of RF & Microwave metrology.
The ST series products are complete miniature RF & Microwave power meters. Each sensor contains a controlling CPU that processes the measurement results and operates the interface. All data and settings are managed by your PC with our windows-based software.
Connecting a sensor directly to a PC is the most cost-effective method for high-precision power measurements, especially if a PC is already used for data acquisition and evaluation. Moving the control and measurement display away from the sensor and into the PC means you save space and reduce cost.
Service technicians will appreciate this product since the power sensor is only 1.7 x 1.350 x 5.2 inches (34x 43 x 132 mm) and can easily be operated from a laptop.
Our goal is to produce easy to use equipment at an affordable price.
LadyBug LB480A




LadyBug的log居然是一只七星瓢虫，初看还以为是动物用品，可那的确是功率计。如此小的体积内集成了功率计和功率探头，可以支持脉冲外形，脉冲（峰值）功率和CW功率测量，一点都不比Agilent的Ｕ2000差。LadyBug生产的功率计一共有6种型号，提供了从10MHz到26.5GHz的频率范围，以及-60~20dBm的功率测量能力，并提供了最好1.7%的精度以及1.5%线性度。内置触发模块，具备内部校准。提供11种时间（闸门）测量，4种脉冲（峰值）测量，以及CDF，CCDF统计分析。值得一提的是LadyBug提供了该类仪器里边最快的测量速度2000次/S。同时最多支持8个功率计，2km的远程控制能力，以及最大10MHz通道带宽。软件方面，除了提供独立应用软件以外，还支持VB，XXXXXt，XXXXXt，C#，C++，不过不支持Labview是一大遗憾。

Pulse Profiling Panel Showing Basic RF & Microwave Pulse Power Measurements

Microwave Pulse Power Measurement Using the LB480A’s Wide Dynamic Range

Pulse Profiling Panel Showing Measurement of a complex signal
关于LadyBug


Richard Hawkins is President of LadyBug Technologies. Like co-founder and Vice President Jon Sigler, Richard is inspired by a company intent on building a better product at a better price and doing it in the U.S.A.
Richard brings twenty-five years of Sonoma County experience in the RF & Microwave Test & Measurement arena to LadyBug Technologies. As an R&D Engineer, Richard developed hardware for Vector Network Analyzers, Microwave Sources, Mechanical Calibration Kits and Large Distributed Monitoring Systems.
Richard also managed a number of R&D projects including Automated Vector Network Analyzer Calibration Devices, RF and Microwave Power Sensors, RF and Microwave Switches and major Manufacturing Test Software efforts.
Richard has additional experience in manufacturing management and precision time and frequency products, marketing and marketing management. This rich background has played a key role in LadyBug's founding and the development of these products.
Richard graduated Magna Cum Laude from Cal Poly, San Luis Obispo California with a BSEE.

Jon Sigler is Vice President and co-founder of LadyBug Technologies. Jon brings over twenty-five years of RF & Microwave Test & Measurement experience to LadyBug. Jon's focus has been software and firmware. This experience serves as an essential compliment to Richard's hardware experience and to the creation of LadyBug Technologies.
Jon's software development experience includes Built-In Diagnostics, EMC Test Software and Firmware, and a variety of Satellite Software Solutions. Jon also has been successful in architecting, managing and developing larger enterprise test software efforts. These complex, long lived projects bridge corporate level organizational boundaries, geographical boundaries as well as process and product boundaries.
Jon's strong background is further enhanced by his marketing management and manufacturing experience as well as a tour as a U.S. Marine in calibration labs.
Jon graduated from Memphis State University with a BSEE.
结论
是时候来个结论了。如果你需要的是手持功率计的话，只有Keithley的3500能满足你的要求。除此之外，如果你看重的是和Labview的无缝连接的话，NI 的USB-5680和Agilent的Ｕ2000不失为好的选择。如果你看重性价比的话，无疑LadyBug的产品具有最好的性价比。当然Agilent的U2000有先天性的优势，可以和你已有的Agilent射频仪器集成，可价格也非常昂贵。