Left Border Content - RF Cafe
Copyright: 1996 - 2024
BSEE - KB3UON
RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling
2 MB. Its primary purpose was to provide me with ready access to commonly needed
formulas and reference material while performing my work as an RF system and circuit
design engineer. The World Wide Web (Internet) was largely an unknown entity at
the time and bandwidth was a scarce commodity. Dial-up modems blazed along at 14.4 kbps
while typing up your telephone line, and a nice lady's voice announced "You've Got
Mail" when a new message arrived...
All trademarks, copyrights, patents, and other rights of ownership to images
and text used on the RF Cafe website are hereby acknowledged.
My Hobby Website:
Sub-Header - RF Cafe
Anatech Electronics Newsletter - November 2013
Anatech Electronics has published its November 2013 newsletter. As always, it includes both
company news and some tidbits about relevant industry events, regulations, and standards. This
month, Sam Benzacar offers his takes on the subjects of analog voltage-tuned filters, legacy
products, reverse microwaves, high-tech feature phones.
The Reverse Microwave?
No, it doesn't use microwave technology, but its
maker, Enviro-Cool Limited of the UK, likens it to a 'reverse-microwave' since instead
of heating quickly it cools quickly, chilling down drinks in cans and bottles to desired
temperatures in 45 seconds. The patented technology, called V-Tex, has become a commercial
product with the help of €930,000 ($1.28 million) from the European Commission. It may be
able to reduce the cost and energy required to cool beverages in stores and vending machines
by up to 90%.
Other attempts have been made to rapidly cool drinks but they have
caused desirable slushing” that V-Tex avoids by agitating the liquid and rotating it to
keep the carbonation in check using a "Rankine
vortex." Rotating the beverage makes the vortex behave like a solid, with the outer liquid
cooling faster than the inner liquid. Cooling rates were improved by collapsing the vortex
and then recreating it, which is the core of the company's ﬁrst patent. Other enhancements
allow the vortex to be interrupted without stopping the rotation, which decreases cooling
The High-Tech Feature Phone Lives
The flip-phone may
be relegated by the smartphone to the bottom rung of the market, but Samsung has just introduced
one that bucks the trend. The SCH-W2014 is an Android 4.3 flip-phone powered by a 2.3-GHz,
quad-core Qualcomm Snapdragon 800 processor with 2 Gbytes of RAM, 13-megapixel rear-facing
camera, 2-megapixel front-facing camera, dual SIM card slots, 32 Gbytes of memory, and a
micro SD card slot. It has a 3.7 in., 800x480-pixel Super AMOLED display. Unfortunately,
it costs about $1,640.
Smartphone Sales Skyrocket
250 million smartphones were shipped globally in Q3 2013, 34% of which were built by Samsung,
which accounted for 83 million of them (Apple shipped a paltry 33.3 million). Nokia shipments
dramatically increased to 15 million including 8.8 million of its new Lumia Windows 8 Phone
models, making the company number three in the market. Overall growth was 10%, nearly twice
that of the same period last year. With the holiday season approaching, growth is expected
to increase even more thanks to the new Samsung Note 3, iPhone 5S, and iPhone 5C.
|A Message from Sam Benzacar
Filters: Still an Excellent Solution
By Sam Benzacar
days, as engineers attempt to digitize functions previously performed by analog components,
it's important to remember that in some cases performing functions in the analog domain
is still preferable. One of the best examples is the analog voltage-tuned filter (VTF).
Unlike digitally-tuned filters (which have their own benefits), analog VTFs tune continuously
so they can settle on any frequency rather than those dictated by the minimum step size
of a digitizer.
That is, they can tune to an infinite number of points anywhere
within a given range, which in Anatech's VTFs is from 225 to 400 MHz. So, whether the desired
frequency is 232.576 MHz or 327.926 MHz, both are achievable, which they might not be with
a digitally-tuned filter.
A VTF is essentially a variable bandpass filter in which
a varactor diode acts as a voltage-controlled tuning capacitor. The primary characteristic
of the varactor diode (also called a Varicap, a TRW Semiconductor trademark) is its capacitance,
which varies with the voltage applied to it. This DC reverse bias voltage is blocked from
the tuned circuit using a blocking capacitor whose capacitance is about 100 times greater
than the maximum capacitance of the diode.
A classic two-section coupled resonator
bandpass VTF uses a Chebyshev topology and consists of two tank circuits tuned to a specific
(center) frequency, one coupling capacitor, and two end capacitors. A varactor diode can
achieve only a limited range of capacitance so it is sometimes necessary to split the desired
frequency range into two bands such as 225 to 300 MHz and 300 to 400 MHz. However, high-speed
switches allow the entire 225 to 400 MHz frequency range to be covered.
Electronics offers three standard VTF models: the surface-mount Model AE225-300VT90 with
a frequency range 225 to 300 MHz, the Model AE225-300AVT102 amplified VTF with 20 dB gain
(225 to 300 MHz), and the Model AE225-400AVT112 amplified VTF (225 to 400 MHz).
more information, please contact us at (973) 772-4242 or by e-mail at
for Legacy Filters?
Our library of more than 5,000 filter designs allows us to quickly “re-create” filters used
in existing systems with their rated specifications and in their original form factors –
without huge costs for NRE. Call or e-mail us today to discuss your requirements. You can
also find more information by clicking the following links:
Bandstop (Notch) Filters
Download Our 2013 Catalog
Download Our Technical Resources
Anatech Electronics, Inc. (AEI) specializes in the design and
manufacture of standard and custom RF and microwave filters and other passive components and
subsystems employed in commercial, industrial, and aerospace and applications. Products are
available from an operating frequency range of 10 kHz to 30 GHz and include cavity, ceramic,
crystal, LC, and surface acoustic wave (SAW), as well as power combiners/dividers, duplexers
and diplexers, directional couplers, terminations, attenuators, circulators, EMI filters, and
lightning arrestors. The company's custom products and capabilities are available at
standard products are available for purchase at the Anatech Electronics Web store,
Anatech Electronics, Inc.
70 Outwater Lane
Garfield, NJ 07026
November 14, 2013
Footer - RF Cafe
Right Border Content - RF Cafe