In article , "Steve Nosko"
writes:

WARNING
LONG WINDED POST BY TWO OLD FOGEYS...

Did I spell that correctly?

Heh. :-)


Then we get into deeper detail and possibly symmantics. I'll keep my
symmantics comments to a minimum since I was simply trying to provide a
simplified comparison with the monimatch and a little info on how they work.

Fine. :-)

I just added some things about directional couplers in general. These
postings are all very public and don't necessarily pertain to one
individual. Sometimes general information is an aid to a reader who
does not post. There's lots more readers than posters in most news-
groups.

Here's some links to couplers and power meters which are current
(checked today to see if they are still there):

http://www.ee.bilkent.edu.tr/~microwave/magnetic.htm

This site has HEAVY theory on - Rectangular waveguide, microstrip
antenna design and analysis, microwave filter design, Lange coupler
design, branch-line coupler design and analysis, directional coupler
design and analysis, 180 degree hybrid coupler design and analysis,
microwave power divider design and analysis. The "design and
analysis" includes an on-line calculator-applet to plug in numbers and
it grunges through the math for the user. It is practically a FREE book
on the basic UHF-microwave passive component region and should
save anyone's wallet to the tune of at least $120 (the old "Matthaei-
Young-Jones" hardcover is more than that now, even after 30+ years).

From the Microwaves & RF magazine archives, there is the February
2001 tutorial "Understanding The Basics Of Microstrip Directional
Couplers" by Leo Maloratsky, pp 79 to 94, a very concise article on a
large subject. Maloratsky worked for Rockwell Collins in Melbourne,
Florida at that time.

For direct SWR measurement using a Bruene detector and using meters
for readout of both forward and reverse power, the QEX article by Paul
Kiciak, N2PK, gives dimensional-construction information on the bridge
for HF and uses AD8307s as logarithmic detectors for both forward and
reverse plus op-amp couplers to the indicating meters. I have a PDF
that lacks the QEX identifying issue and page that was obtained from
another in July 2001, can't supply the QEX issue date or pages.

The Bruene bridge was first used in military T-195 transmitters that
became operational with USMC and US Army in 1955...part of a very
easy to use HF vehicular Tx/Rx using tubes and long vehicle whips.
Collins did the design under contract. A version of the Bruene
bridge is still used today in the US military in the AN/PRC-104
backpack 20 W HF radio which has an auto-tuner for the whip.
Hughes Aircraft designed, became operational in 1986.

I emphasize measurement methods because a finished coupler or
bridge or whatever needs to have something to measure it at lower
powers than available on Bird Wattmeters or similar. One of the
nicest applications of the Analog Devices AD8307 as a Wattmeter
with an 80 db dynamic range is on Thomas Schirrer's website:

http://www.webx.dk/oz2cpu/radios/milliwatt.htm

That one uses only two ICs, the AD8307 and a Microchip PIC16F876.
Accuracy of RF power measurement is all up to the AD8307 which
can work up past 500 MHz, has direct connections of RF input to the
AD8307. The PIC does conversion of AD8307 DC output volts to
either Watts or dbm and also controls the LCD panel unit (2 x 16
character integral LCD panel and driver). No other active devices are
needed except for the DC power supply. With appropriate programming,
serveral different PIC microcontrollers can be used. Several others have
copied the same circuit with variations on the case on display legend,
as indicated on the website. Simple and elegant. Calibrate once and
such will remain, error dependent solely on the AD8307.


...Analog Devices log detector is
I saw that little bugger in QEX. Pretty cool!

Lots of information on the Analog Devices website for datasheets and
application notes on their full line of logarithmic detectors. Why anyone
still wants to depend on germanium diode detectors with very limited
dynamic range and non-linear detection is beyond me. :-)

Len Anderson
retired (from regular hours) electronic engineer person