Recycling People and Techniques

Many EMC professionals, myself included, have been involved with downsizing, layoffs, or whatever term is currently in use. The end result is that many people have to refocus or recycle their careers.
IEEE-USA has created the Professional Activities Committee for Engineers (PACE) network to promote the professional interests of their members. A primary focus is helping members to match their skills to the current job market. I was appointed to be the EMCS PACE Coordinator because of my years of EMC experience and my own change in career direction. My new career path is in the Wireless Communications Section of a small, privately owned engineering company.
While working on improving the adjustment efficiency of a five-channel VHF base station, I developed the following technical application. Most EMC experienced personnel are very familiar with clamp-on broadband RF current probes that are sold by several manufacturers. Different models are available covering different frequency ranges and aperture sizes.
A design requirement was to verify and adjust the power output of each transmitter in a combined five-transmitter VHF system. Typical operation was to operate the control channel transmitter at the licensed Effective Radiated Power (ERP). Other transmitters were then adjusted to be three decibels (dB’s) below the control channel.
The existing recommended procedure was to insert a wattmeter in cable N and to set the power output of the control transmitter, TX5 to the licensed ERP. Verification of the band pass filters (F) and isolator (ISO) attenuation required the following steps:

  1. Insert the wattmeter into one of the cables
  2. Tune the applicable transmitter
  3. Record the information
  4. Disconnect and move the wattmeter to another cable
  5. Analyze the data

This procedure was very labor intensive and also susceptible to connector damage. It was modified to utilize a clamp-on broadband current probe. The selected probe was an A.H. Systems model BCP-512 with a frequency range of 1 MHz to 1000 MHz to cover the VHF frequency used. The probe output was connected to a suitable spectrum analyzer. This configuration allows the rapid adjustment of the other four transmitters to 3 dB below the control transmitter level.
Using a clamp-on probe provided several additional benefits. Clamping on to the transmitter output coax lines (A-E) allowed the spectral analysis of each transmitter; moving the probe to the filter output lines (F-J) allowed the verification of the manual tuning of the band pass filters (F1-F5); and finally, moving the probe to the isolator output lines allowed the verification of the listed attenuation of each isolator.
The application of a proven EMC technique greatly improved the communications base station measurement and verification. Additionally, multiple coaxial cable disconnects were reduced to only one, thus cutting short the time required and forestalling possible connector damage. The most interesting part of this test was that I could find no references describing the use of current probes in communication applications.
Other EMC procedures may be applicable for use in other technical areas such as building construction and power design. Please send me information of other EMC techniques that have been “recycled” to new uses to boost efficiency and innovation in a new area. I can then share the information with others who are now in a new non-EMC career. EMC

Bill McGinnis is a Senior RF Designer with Alexander Utility Engineering, Inc. where he designs and deploys various communications and SCADA RF systems. He has over four decades of civilian and military EMC experience. Professional activities include IEEE membership, with six years elected to the EMCS BOD, EMCABS editor, and currently the EMCS PACE Coordinator. He may be reached at



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