Flow for PA MMIC Design
A new white paper from AWR, "RF/Microwave EDA Software
Design Flow Considerations for PA MMIC Design," examines a gallium arsenide
(GaAs) pseudomorphic high electron mobility transistor (pHEMT) power amplifier (PA)
design approach from a systems perspective. The design flow and its essential features
for most PA design projects is illustrated through the design of a simple, Class
A GaAs pHEMT monolithic microwave integrated circuit (MMIC) PA using AWR's Microwave
Office® high-frequency design software.
IEEE USA also sends out their "today's engineer"
newsletter on Fridays. Here are some items that strike my fancy.
Secret for Better
- What Keeps
Hall of Fame:
in Hagerstown, Maryland
Newton famously said, "If I have seen farther it is from standing on the shoulders
of giants." His statement was figurative, of course, but I can now say literally
that I have stood on the shoulders of a giant. Somewhere recently, I don't recall
where, I read that although American Radio Relay League (ARRL) founder
Hiram Percy Maxim was born in New York and spent most of his adult
life in Connecticut, he was buried in Rose Hill Cemetery located in Hagerstown,
Maryland. That just happens to be where Melanie and I stop a couple times each year
to visit her mother. We lived there ourselves for about three years in the early
1990s. That day, I surely stood if not exactly atop Mr. Maxim's shoulders, then
very nearly so as I maneuvered to take this picture of his grave marker. Why is
he buried in Maryland, you might ask? That is where his...
Here a few new headlines for you from LinkedIn,
in case you don't receive their weekly update. They usually have some pretty good
stuff. I'm not big into the social media scene, but LinkedIn is kind of like Facebook
with a brain required for participation.
Who's Your New Mobile
Carrier? How 'Bout Wi-Fi?
5 Things You Have to
Unlearn to Succeed at Work
Every Step You Take,
Every Move You Make
You've Got the Degree,
Now Get out the Passport
for Continued Support!
LLC is a global supplier of RF &
Microwave components. Their products include SMT hybrid couplers, wire
bondable passive components, coaxial products, test fixtures and very
useful test boards for evaluating components. The Electro-Photonics team can
support your small R&D design requirements with RF & Microwave test
fixtures and save you valuable design and characterization time.
An extraterrestrial threat to existence, be
it an impending asteroid strike or an intelligent being's announced intention to
do harm to the earth, would probably be required these days to invoke the sort of
voluntary personal sacrifices of today's average citizen that was exhibited in the
enthusiastic, patriotic response by Americans to the
'V' for Victory campaign during World War II. You
no doubt have seen pictures of kids pulling wagons filled with metal scrap, rubber
tires, and glass milk and pop bottles collected for the war effort, and pickup trucks
piled high with sections of pipe, car parts, and retired furnaces. Resources were
relatively scarce at the time, and material was being consumed very quickly in the
effort beat back the aggressive advances of Axis forces throughout Europe, northern
Africa, and the South Pacific. This article from a 1942 edition of Radio Retailing
Today encouraged radio repairmen to check with customers during service calls...
Advertisement circa 1942
Triplett is a well-know name amongst electronics
technicians and engineers who have been in the business for any length of time.
Triplett meter movements (aka panel meters) were considered to
be top-of-the-line product in the days before digital meters and displays. They
were used in industrial instrumentation, in military equipment, and in amateur radio
gear. Triplett is still in business today but it appears they no longer sell just
meter movements, although there is a large supply (new and used) available on eBay
and Ham radio websites and swap meets. This advertisement for Triplett Thin-Line
Instruments appeared in the September 1942 edition of Radio Retailing Today
Skyworks Solutions, Inc. unveils a new device
for cellular infrastructure, VHF/UHF military and public safety radios. The SKY12408-321LF
is a 50-600 MHz, 6 dB
that is pin-for-pin compatible with its 12 dB SKY12407-321LF attenuator, but
ideal for IF radio applications requiring lower overall attenuation and gain control.
The new solution also offers a novel differential I/O design and fast settling time
for applications that down convert to a low Intermediate frequency.
'Bug?' You'll Be Surprised,
It was one of those, "Well, huh!," moments
for me when I read in a story from the IEEE that claims the first recorded use of
the term 'bug' in reference to a problem in hardware was not by U.S. Navy Admiral
Grace Hopper and her colleagues, as popular belief (including mine) goes. Their
finding of a dead moth - a 'bug' - in
a Harvard University computer is legend, but evidently was not the first known instance.
Instead, it was none other than Thomas Edison who may have originally used the term.
Before you go accusing the respected Institution of waging a War on Women (a popular
indictment of convenience these days) for denying credit where credit is due, nobody
is implying that she purloined Mr. Edison's term. According to researcher Dr. Paul
Israel, editor of the
of Thomas A. Edison, and the IEEE History Center, Edison regularly referred
to technical problems as bugs. "In 1873 Edison first confronted what he later called
a bug when he began developing a quadruplex telegraph
2-Way SMD Divider/Combiner
LLC announces the availability of Y2D-900R, a
high power 2-way SMD power divider
/ combiner. Our new Y2D-900R power divider/combiner operates from
700-1000 MHz and can dissipate up to 350 W in a small 480 mil x 650 mil
package. This power divider offers excellent isolation, low insertion loss,
and good phase balance for most critical applications. The Y2D-900R requires
an external 100 ohm resistor for operation. Power will only be limited
by the size and power ratings of the chosen resistor.
Instruments for Support
Instruments designs and manufactures the world's finest high-precision
Line (PDL) instruments and modules. All instruments are fully programmable via
GPIB interface, and are suitable for use in high frequency RF signal applications
as phase shifters or where an extremely high precision and accurate amount of delay
is required. Colby Instruments has been helping deliver RF Cafe since 2009.
MPN-13 Radar Model
USAF radar technician
Elbert Cook just sent some photos of the
TPN-19 radar units that were based with him at the 3rd Combat
Communications Group (aka 3rd MOB, aka 3CCG) at Tinker AFB, Oklahoma. He also sent
the first couple pictures of a scale model of the
unit that he has begun. Stay tuned for project updates.
30 dB Coupler for 2
to 4 GHz
VidaRF has introduced a
high power 30 dB coupler with a 2-4 GHz
frequency range (other coupling values available). Average power is 500 W,
with a Peak of 8 kW. Loss is 0.25 dB (excluding coupled power), directivity
is 18 dB, and VSWR is 1.30:1. Connector type is "N" Female on all ports. Custom
designs available upon request. VidaRF offers a wide selection of Directional Couplers,
Dual Directional Couplers and Hybrid Couplers, designed to cover 0.1 GHz to
An Expert Testimony
fair number of people who visit RF Cafe have at some point been involved as an Expert
Witness for a court case involving product liability and/or IP ownership or infringement.
They quickly learn how important it is to
have competent and
renowned legal representation.
IMS ExpertServices is a law firm specializing in expert witness cases. Every
month or so they send me an article about specific court cases that could be of
interest to RF Cafe visitors. This particular article is titled "Fortune Telling &
Reliability? An Expert Testimony Enigma." It illustrates how dicey the process of
selecting appropriate Expert Witnesses can be for legal teams - especially given
the subjective nature of judges who decide on admissibility of evidence.
DIN 7/16 Connector
DongJin Technology Innovation announces the immediate
availability of very affordable composite DIN
7/16 connectors. The body material is a composite plastic black with silver-plated
bronze contacts, as opposed to a standard brass body and beryllium-copper (Be-Cu)
contacts. This newly developed 7/16 connector is seeing a steep increase in use
in leading countries like Japan, Germany, and the USA.
Technologies as a Sponsor
A former comrade contacted me recently
to say he, too, had moved on from where we used to work. He is a very capable RF
engineer and is now retired from his 20+-year
stint as a communications officer in the Air National Guard. Parsec Technologies
is now the beneficiary of his know-how. He recommended that they try advertising
on RF Cafe and the result is this announcement. Thanks Conrad! Parsec's LNAs have
been designed to optimize GaAs for the ultimate combination of noise figure, gain,
and IP3. We are redefining what high performance
amplifiers are in today's market for low voltage, low power amplifiers with
low noise, high gain and high IP3 normally found on amplifiers that consume much
- the 'Portaphone'
Sending texts must have been a real challenge
on this early portable phone. Aside from having to type out your message on a standard
telephone keypad (oh, the humanity), the baud rate must have been snail-like. The
article doesn't mention whether dropped calls were a big issue and whether there
was a massive marketing plan with a bespectacled "Can You Hear Me now?" guy. I'm
just kidding, of course. This news item appeared in a 1955 edition of Air Trails:
Hobbies for Young Men. Before you laugh at the
dipole antenna and carrying case, consider that it was only a little over two decades
ago that Motorola debuted its famous M800 'Bag Phone.' From the magazine: "Portable
two-way radio phone...
Appreciation of Their Support
is a world
leader in the design and development of surface mount
VCO modules & PLL frequency synthesizers
for the commercial microwave/RF
wireless market. RoHS compliant signal source products currently range from 40 MHz
to 13.5 GHz bands. PLLs available in integer, fractional-N and single frequency
models. VCOs feature coaxial resonator based and high-Q distributed resonator construction.
and Repairing Commercial Electrical Equipment, by David Herres, is another in
a series where he has leveraged his many years working as a Master Electrician.
It is his first work that offers a practical approach to diagnosing and repairing
commercial / industrial electrical equipment – covering everything from motors,
computers, elevators, and fire alarm systems to heavy-duty ovens and audio equipment.
This one-of-a-kind guide can help you become more competent in your profession.
Inside you'll find ways to become faster, more efficient, and able to achieve a
much higher success rate in restoring large electrical equipment without damaging
it, introducing an additional defect, or creating a hazard.
There don't seem to
be many electronic products these days without some form of software in them (EEPROMs,
ASICs, μProcessors, FPGAs, etc.); indeed, many electrical engineers also wear
a software engineer's hat. Two consultants that advertise on RF Cafe, Lance Lascari
(RF Dude) and Joe Cahak (Sunshine Design) come to mind, along
with many others known during my career. I've even done a bit of software and FPGA
programming myself. This installment of EDN's "Tales from the Cube" series
involves an engineer who needed to live in both worlds in order to solve his problem
with a meter designed by someone long gone from the company. Mihaela Costin applied
a bit of ingenuity to make the best of a bad situation...
New Cable Builder App
The New Cable
Assembly Builder tool on everything RF lets you specify your cable assembly
requirements in a form and on submission directs it to over 20 companies that can
manufacturer it. Your query will be directed to the leading cable assembly manufacturers
– Aeroflex, Emerson, Amphenol, San-tron, RF Industries, VidaRF, Pasternack, SV Microwave
and many others. You no longer need to send out individual request to each manufacturer
- everything RF does that for you. The tool has been optimized for Desktops, Tablets
and Mobiles so you can use it from anywhere on any device.
New Combiner and Duplexers
Electronics has released new designs for a 710-716 MHz / 740-746 MHz bandpass
combiner , 779 MHz / 749 MHz ceramic duplexer , and a 1710-1755 MHz
/ 2110-2155 MHz cavity duplexer. All can be ordered directly through their
AMCrf web store.
Study Radio Course c.1948
Davis sent me a link to Mike Yancey's (KM5Z) website where there is a scanned
version of the 1948 National Radio Institute (NRI) home study course for radio technicians.
It is a very extensive collection of 55 volumes (PDF format) covering topics like
Simple Radio Circuits and Meters, Radio Coils and How They Work, How Detectors Work
in Radio and Television Receivers, Current, Voltage and Resistance Measurements,
and How to Eliminate Man-Made Interference. KM5Z also has some other good content
that you might be interested in while you're there like a 1958 edition the RCA Radio &
TV Course, online calculators for toroids, inductor Q, voltage dividers, and antenna
field strength, and radio restoration projects.
for Continued Support!
Innovative Power Products, Inc. has more than 25 years of experience
designing and manufacturing RF Passive Components.
Our couplers, combiners, resistors, and terminations incorporate the latest technology
in materials available, which equates to unrivaled product performance. IPP has
been with RF Cafe since early 2008.
Microwave Product Digest
Microwave Product Digest just posted
articles from their August edition. Lots of good stuff there, as usual.
How to Calculate Peak
Uncertainties, Sook H. Wong
Conducting Noise Figure
Measurements, Sean Flavin
EMC Test Equipment and
Services Market – Another
Opportunity in China,
USB Brings Portability and
Flexibility to MW Test Bench
– Wherever it May Be,
Building Low PIM Coax
Assemblies with Consistent
Something old, something new, something
borrowed, something... brown. My paraphrasing (lamely) of the old saying for bringing
good luck to a bride aptly describes Adam Vaughan's effort in building his 'Twittertape Machine.' Adam's machine
prints out Twitter messages on a paper tape in the manner of early stock market
tickers. "This astounding device will print a permanent copy of all Tweets yet requires
no ink or computer." So says a proclamation in vintage serif font and decorative
trimmings on the website's homepage. Indeed it does. The prototype uses two wall
wart AC/DC adapters, an Arduino-style microcontroller with an Ethernet interface,
a Bell jar, a thermal printer, and miscellaneous clock parts. Full details of the
design and operation are provided, including a video. It checks for and prints out
available Tweets every 30 seconds. Before you get upset about altering historic
"If you think it's expensive to hire a professional
for a job, wait until you hire an amateur." -
Red Adair, famous global firefighter. Red Adair is the guy who put out all the
Kuwait oil well fires after Hussein's troops ignited them while retreating from
occupied territory. Television 'experts' said those fires would burn for decades.
They were out in months.
Crossword for 8/25/2013
Take a break and work this week's
wireless engineering themed crossword puzzle. All the words are
pulled from a hand-built list of terms, names, and abbreviations that have only
to do with science, mathematics, and engineering. If you want a crossword with names
of movie stars and obscure countries, try the local newspaper. If you want to exercise
your nerd knowledge, this is the one for you.
PMI Model No.
PEC3-40-30M26R5G-6R0-12-12-SFF is a 30 MHz to 26.5 GHz Low Noise Amplifier
that provides greater than 35 dB of gain while maintaining a maximum gain flatness
of ±3.5 dB maximum over the operating frequency. The noise figure is 6.0 dB
typical and offers an OP1dB of +12 dBm minimum. The operating voltage
is +12 to 15 VDC and the current draw is 700 mA maximum.
of the Oblivian Customer
You're going to love this installment of Sherlock
Ohms. Even if you have never had to deal directly with customers for a product performance
issue, you will easily empathize with engineer Jonathan Eckrich in "The Case of the Confused
Customer." The incident reminds me of a story I read years ago by an engineer
who worked on development of one of the early computer languages - I think it was
FORTRAN. The user called to complain that a section of code was failing and demanded
assistance because in his opinion, the language kernel was faulty. The caller's
name was not disclosed, but the engineer said he was a notable figure. After listening
to the problem, the cause seemed obvious, so the engineer (wish I could remember
his name) instructed the guy to make sure he was using the "less than" symbol, to
which the guy responded that he is no idiot and the problem must be something else...
and its Application
I challenge you to find a calculus lesson
in a modern-day electronics magazine. In 1932, not all that long after Isaac Newton
developed differential calculus (that's a joke), Radio News magazine ran
a series of "Mathematics in Radio" articles that included, among other topics,
a few lessons in calculus. Anyone who has taken college-level science or engineering
courses knows how indispensible calculus is in working out many circuit, physics,
and chemistry problems. My appreciation for calculus came when I realized that it
actually allowed me to derive the kinds of standard equations that are commonly
seen in lower level applications. For instance, if you needed to know the volume
of a sphere, you could look up the familiar Volume = 4/3 π r3
formula, or you could write the equation...
Student Design Winners
Corporation, the innovation leader in high-frequency EDA software, gifted its software
to the winners of the High Efficiency Power Amplifier (HEPA) and Software Defined
Radio (SDR) Student Design Contests offered at the 2013 IMS MTT-S conference. The
gifts are part of the
AWR University Program, which sponsors student design contests throughout the
world to encourage students to become involved in the dynamic profession of microwave
and RF engineering and to apply their knowledge to practical designs using the highly
efficient AWR design methodology.
Here is the latest
bunch of engineering career and employment news headlines from IEEE's JobSite.
Valley's Dirty Secret
Bias (it ain't just in SV)
Layoff Taboo: Japan's
Help You Land Your
Does Your Entry-Level Job
Have Growth Potential?
Here are a couple more I found while looking around:
Confidence on the Rise
Five Ways Job Seekers
Can be Proactive While
Engineering Grads Enjoy
Greater Job Prospects
The Myth of America's
Missing Software Engineers
Dong Jin Technology Innovations
helps to deliver RF Cafe through their advertising, which was just renewed for another
term. Dong Jin designs, manufactures, and assembles
RF connectors, cable assemblies and components.
Competitive price, on-time delivery and best quality. No minimum order size. One-day
delivery. ISO9001, ISO14001, RoHS certified.
Stopped by Lightning
is another great RF troubleshooting saga; in fact, it would make a good short action
film. Designing and implementing proper lightning protection can be a real
challenge - and quite expensive. Lightning has a nasty habit of seeking out and
exploiting weaknesses. Author Rod Hine doesn't cite improper protection as the culprit
for causing his woes in his telling of, The Case of the "Earth
Station Stopped by Lightning." A couple decades ago I worked with a team that
designed a prototype weather radar system with cobbled-together parts that included
a surplus military phased array antenna. After doing all the initial design, build
and test at our facility, everything was moved to an open air site that sat at the
top of a ridge which was known to attract lightning like trailer parks attract tornadoes.
A fair amount of effort went into lightning mitigation over the years, so we felt
comfortable hooking into the existing system. All went fine for the remaining time
I was there. About a year later...
Vendor Pages Added
being contacted by a friend of mine who works for
Parsec Technologies about adding their company to my categorical
Manufacturers and Services
pages, I realized that I blinked and missed the need to add resources for the relatively
new fields of
Software Defined Radio,
White Space, and
Mobile HDTV. Having just awoken, there are now the beginnings
of pages for them. In searching for companies to include it quickly became apparent
that most of what is available to fill the need is re-purposed ICs and hardware,
but as the technologies mature and standards are established there will be more
specialty products. Parsec Technologies is one of those companies working now to
fill the need.
VidaRF has introduced a low loss
Waveguide Isolator, model
VDWR42-2021-A, with a frequency range from 20.2-21.2 GHz. The isolator offers
0.1 dB loss, isolation 28 dB, VSWR of 1.11:1. Forward power handling is
3 watts with operating temperature -40 to +80 C. Pressure sealed to 10 psi.
Once radios in the family car became a standard
accessory, a push ensued to make them cheaper, more reliable, and service-free.
A major Achilles' Heel was the high voltage power supply required to energize vacuum
tubes. Known as vibrator power supplies due to using an oscillator to convert the
battery's 12 DC supply (some autos still used 6 V systems) into AC that could
be transformed up to the 300 volts used by most tubes of the day, most early failures
were attributed to the circuits. They also caused annoying noise in the audio output
if careful filtering and installation was not performed. Having been invented only
a couple years earlier, transistors were being designed into the power supplies,
but low-voltage tubes were still needed for the electronics. In response to the
demand, low-voltage tubes were created to fill the gap until acceptable transistors
became available for a fully solid-state radio. This article discusses some of the
low voltage tube design and methods employed to overcome them.
Active Sensing Systems
Design for Active Sensing Systems: A Computational Approach, by Hao He Hao He,
Jian Li, and Petre Stoica, is my Featured Book for this week. With a focus on developing
computational algorithms for examining waveform design in diverse active sensing
applications, this guide is ideal for researchers and practitioners in the field.
The three parts conveniently correspond to the three categories of desirable waveform
properties: good aperiodic correlations, good periodic correlations and beam pattern
matching. In addition to numerical results, the authors present theoretical analyses
describing lower bounds or limitations of performance.
Cambridge University Press.
so now I have read about someone who credits social media - LinkedIn specifically
- for success. Judy Warner,
of Transline Technology, responded to the "Fake Twitter Follower Factory"
commentary that I posted on LinkedIn to say she has had an overwhelmingly good response
from reaching out to and engaging the LinkedIn community of engineers. In fact,
Judy's experience was so spectacular that in a few short years she went from being
a connectionless marketing exec re-entering the PCB marketing realm after a decade-long
hiatus, to being a sought-after expert in her field. Read her short article "Does Marketing Matter?"
in the April 2013 edition of the pcb magazine (page 62). Maybe Judy's feedback
to my LinkedIn post means I, too, can now claim social media success!
I've always been a bit dubious
about the whole social media thing. Yes, it can be a great medium for connecting
with old friends and maybe getting some breaking news, but otherwise services like
Twitter seem to mostly
be a time-wasting enabler for people with too little meaningful purpose in their
lives. Achieving the largest number of 'Followers' is now a lifetime goal in order
to assert and prove popularity and dominance in society. Catering to vanity is big
business so as you might expect, there is a plethora of opportunists who offer to
inflate the Followership of gullible Twits. A recent story in Inc magazine, one
of many such stories in many news reports, illustrated just how easy it is given
even a modest cash outlay to buy Followers - some charge as little as a penny apiece.
If you are thinking of starting a Twitter Follower business of your own, businesses
will also sell you 'verified' e-mails address batches, Captcha defeaters, and HideMyAss.com
Have I mentioned how
much I appreciate good graphs and illustrations for conveying information? Yeah,
I guess I have... often. The adage about a picture being worth a thousand words
certainly holds true - even if the thousand words inadvertently describes the artist's
crappy attempt to get his/her message across. This particular graphic presents information
on some of the vast resources of [mostly] free online educational sources for engineering
and related topics. Massive Open Online Courses (MOOC) was launched in 2008 at the
University of Winnipeg and is credited with birthing the idea (at least for being
the first to successfully implement it). There are, of course even more courses
in other areas of interest. Flight vehicle aerodynamics, astronomy, solar energy,
physics, numerical statistics, even sci-fi and creative writing, all useful in a
well rounded engineering experience, are among the listed types...
The writers at
Test & Measurement magazine hit a high note this month with articles. Enjoy.
Components Meet Specs
by Jeffrey Dierker
and Reliability Degradation
Issues, by T. Nishimura
Improve Wireless Testing
of Sensitive Devices,
by Per Nielsen
Repair as a New Advertiser!
Repair is based in Cocoa, Florida, and focuses on servicing
spectrum analyzers and
"All of our technicians are military PMEL graduates." After their tenure, they spent
time in R&D labs, USAF PMEL labs, and commercial calibration labs. Repair
calibration services for new equipment & extend life of obsolete high performance
acquisition is the end of a dream." - Jake Lodwick, co-founder of Vimeo. This quote
appeared in the July/August 2013
Inc magazine, where Mr. Lodwick describes the Heck he went through with
his company. He further states, "If you truly believe in the potential of your company
to change the world for the better, there's no excuse for settling for an acquisition."
for August 18, 2013
Take a break
and work this week's
engineering themed crossword puzzle. All the words are pulled
from a hand-built list of terms, names, and abbreviations that have only to do with
science, mathematics, and engineering. If you want a crossword with names of movie
stars and obscure countries, try the local newspaper. If you want to exercise your
nerd knowledge, this is the one for you.
Saturn-Like Ring of Dipoles
do you think of the USAF's plan to deploy a band of
millions of tiny dipole
antennas into orbit around Earth for communications support? Because over-the-horizon
(OTH) radio communications rely on the upper atmosphere being conductive to reflect
radio waves, it is essential that there always be something for bending signals
back to Earth rather than allowing them to escape into space. The ionosphere
has many identified regions that do a good job of reflecting signals of certain
wavelengths during particular times of day and under special atmospheric conditions
cause by solar activity. There are times when reliable OTH communications are not
possible because of severe coronal mass ejections (CMEs), high meteoric activity,
and even terrestrial events like major volcanic eruptions. Even predictable variation
in ionosphere characteristics like the diurnal blending of the F1 and F2 layers
into a single F layer complicates emergency and strategic communications planning...
Repair for Continued Support
Both BRL Test and their
Analyzer Repair division are helping to
deliver RF Cafe by advertising. BRL Test Analyzer Repair specializes in the repair
of spectrum and network analyzers. They are a leading dealer of new and reconditioned
test and measurement equipment. They buy, sell, rent, lease, repair and calibrate
all types of general purpose test and measurement equipment.
Inadvertently Waive Protection?
witnesses play a big role in most of the court cases that get reported here.
is a law firm specializing in expert witnesses. Every month or so they send me an
article about specific court cases that could be of interest to RF Cafe visitors.
This particular article is titled "Can Expert Statements Inadvertently Waive Protection?" It the
case, an expert witness used by Company A to compel Company B to submit to claims
was not intended to be used in court and so per Company A, he/she should not be
able to be deposed during the discovery phase of the lawsuit (it involved faulty
materials in a transmission). The expert witness' opinion was quoted but not declared
as evidence. The laws pertaining to testifying and non-testifying experts are, as
you might imagine, complex and prone to the subjective whims of courts even though
most might consider the codified law to be quite clear. The lesson here is to be
careful how expert witnesses are handled, even if you have no intention of using
their opinions in court.