ARLA/CLUSTER: Perdas nos conectores???

[Carlos Mourato]

caros colegas
Segundo vejo escrito, ou vi mal, parece-me que o referido colega americano
testou uma simples ficha PL259 a 2 GHz com 1 Kw.
Parece-me um exagero, tais dados, até porque as perdas assinaladas devem ser
muito maiores. Um ligador coaxial do tipo PL, nem sequer têm uma impedância
constante, pelo que é totalmente desaconselhado em frequências superiores a
300MHz. certamente, que 1 Kw a 2 GHz o desintegrariam imediatamente,
transformando o dito conector, num pedaço de carvão.
Por outro lado, e mesmo que o dielectrico seja em teflon (coisa que so
acontece em fichas PL de marcas conceituadas) a perdas por retorno de
potencia, devido à onda reflectida provocada pela impedânica não constante
da ficha, especialmente em zonas de GHz, ultrapassam facilmente os 2 dBs,
Cada macaco no seu galho, ...Que é como quem diz: Cada ficha sua função e
sua frequência.
Acima de 300/400 MHz, e para niveis de alguma potência, tem que se ter uma
ficha apropriada.
Se a isto juntar-mos o "plástico branco" a imitar teflon, e o "ferro
cromado" a imitar latão prateado, coisa muito frequênte nas fichas da "loja
dos 300", então teremos no caminho certo para estar a perder em usar fichas
baratas, que muitas vezes tem rosca dificiente, ficam largas, aquecem,
introduzem estacionárias etc, etc, etc!
Já agora podem dar uma olhadela neste material.

*Common Coaxial Connectors*

Below, I present a digest of important information about coaxial connectors.
Most of these are for RF and microwave frequencies, but a few of the more
common ones used for lower frequencies are included for completeness.

*Why different connectors?*

Many coaxial connector types are available in the audio, video, digital, RF
and microwave industries, each designed for a specific purpose and
application. Much of the development of the smaller connectors that perform
well into the GHz and millimeter wave range has been conducted by test
equipment measurement companies. One of their considerations is the number
of connect-disconnect cycles that a connector pair can withstand while still
performing as expected.

*Why different sizes and frequencies?*

The frequency range of any connector is limited by the excitation of the
first circular waveguide propagation mode in the coaxial structure.
Decreasing the diameter of the outer conductor increases the highest usable
frequency. Filling the airspace with dielectric lowers the highest frequency
and increases losses. The mating process typically changes the geometry of
the mating surfaces and resistance loss at those interfaces as well as
geometric changes result in variation of impedance and loss.

Some RF connectors are sexless (such as the HP/Amphenol APC-7 and the
General Radio GR874 and GR900BT). Most connectors have female structures
with slotted fingers that introduce a small inductance. The fingers
accommodate tolerance variations, but reduce repeatability and may
ultimately break after 1000 connections. There are slotless versions of
connectors available, but they are, for the most part, relegated to
instrument interfaces. Slotless female connectors are very difficult to
clean and require very careful connection and disconnection.

*Sex and Connectors*

Those unaccustomed to the use of the terms "male" and "female" to describe
connectors will have to get used to this time-honored engineering
nomenclature. Those of us who work with them regularly use the terminology
without a second thought. One day a number of years back, my daughter (who
was about 8 years old at the time, if memory serves) was in the lab with me
while I was working at the network analyzer with one of the grad students.
She overheard our conversation, peppered as it was with the terms "male
connector" and "female connector". After we were done, she asked me why the
connectors were named that way. Well, this was a conversation I had expected
to have in somewhat different circumstances, but I gave her a quick summary
of the "how-babies-get-made" story, followed by the analogy that is implied
by the connector terminology. She thought about it for a few moments when I
was done, and then said, "Daddy, that's just weird." It's hard to argue with
that.

*Connecting and Disconnecting*

RF and microwave connectors are precision-made parts, and can be easily
damaged by mistreatment. You should start with all connector surfaces as
clean as possible, using a solvent such as alcohol or a special-purpose
cleaner to do the job. Use as little as you can, and in no event contact
dielectric spacers or resistive materials (as used in loads) with the
solvent, since these can be irreparably damaged by the solvent. As a general
rule, if the connectors have threaded sleeves, you should rotate these to
tighten, leaving the rest of the connector (and cable) stationary. If other
parts of the connector are twisted while tightening or loosening, damage can
easily occur.

Connecting 7 mm connectors is somewhat different, and perhaps
counterintuitive. These are sexless connectors, and the mating surfaces
mount flush and are held together by a single rotating sleeve. The mating
sequence is:

1. Each connector has an outside rotating sleeve. On one connector, rotate
the outer sleeve so that the threaded connector sleeve extends completely
out from the outer sleeve. Do this on any fixed-mounted connectors, such as
those on the test ports of a network analyzer. On the other connector,
rotate the outer sleeve so that the threaded connector sleeve recedes
completely into the outer sleeve.

2. Mate the surfaces flush and rotate the forward sleeve to engage the
threads of the other connector.

3. Complete connection is made when the forward rotating sleeve is tight and
the other sleeve is loose.

 *Caution: one sleeve  must be loose. Tightening down both sleeves can cause
connector damage.*
------------------------------

  *COAXIAL CONNECTOR CHART**Connector Type* *Other names (or mates with)**
Female**Male**Maximum Frequency* Phone plugs and jacksTS,  TRS  100 kHz or
lessEver see those old telephone switchboards with hundreds of jacks and
patch cords and plugs? Those are phone jacks and plugs, also known as TS
(Tip-Sleeve) for two-conductor connections, or TRS (Tip-Ring-Sleeve) for
three-conductor connections. They are now used widely with musical
instruments and audio equipment. The phone plug is the male connector, a
phone jack is the female connector. The standard diameter of the plug is
0.25", but many smaller sizes are available as well. These are really only
suitable for audio frequencies. RCAPhono plugs and jacks 10 MHzA round,
press-on connector commonly used for consumer-grade audio and composite
video connections.  In most recent home stereo equipment, the jacks are
color-coded as follows:  red (audio-Right), black or white (audio-Left) and
yellow (composite video). *Generally not a constant characteristic impedance
connector.* UHFPL-259 (male), SO-239 (female) 300 MHz or lessThe UHF type
connector saw its conception in the early 1930's, a time when VHF/UHF
technology was quite new. The forefathers of VHF were in many cases Amateur
radio experimenters, most with Engineering and technical backgrounds. They
began experimenting and working the VHF frontier around 1926. Soon
thereafter research into FM radio and Television began and out of this era
came the then named UHF connector. Manufacturers of UHF plugs and receptors
all state that this type connector are of generally *non-constant
(characteristic) impedance* and are suitable for use up to 200 or 300 MHz
only, depending on production quality. They also state that the UHF
connector can be used up to 500 MHz with a cautionary note of reduced
performance.

The so named UHF connector from the past is not really suitable for use
above 300 MHz at all. Perhaps the exception to this would be when a cheap
and rugged system is required where loss and good signal to noise ratio is
of little concern. However, even for frequencies as low as 144 MHz, if low
loss and good signal to noise ratio are very desirable, the use of UHF type
connectors is not recommended. The UHF connector still has a place in many
applications where a robust but economical RF connector is required, but for
serious applications its use should be limited to below 100 MHz. The N type
is far superior in performance, and it should also be noted the BNC type
connector is similar in performance to the N type, but has the disadvantage
of being less rugged.
FVideo 250 MHz to 1 GHzThe “F” series connectors are primarily utilized in
television cable and antenna applications. Normally these are used at 75 ohm
characteristic impedance. 3/8-32 coupling thread is standard, but  push-on
designs are also available. BNC  2 GHz or higherThe "*B*ayonet
*N*eil-*C*oncelman"
or "Bayonet Navy Connector" or "Baby Neil Connector", depending on the
information source. Karl W. Concelman is believed to have created the "C"
connector. The BNC was designed for military use and has gained wide
acceptance in video and RF applications to 2 GHz. The BNC uses a slotted
outer conductor and some plastic dielectric on each gender connector. This
dielectric causes increasing losses at higher frequencies. Above 4 GHz, the
slots may radiate signals, so the connector is usable, but not necessarily
mechanically stable up to about 10 GHz. Both 50 ohm and 75 ohm versions are
available. TNC  2 GHz or higherA threaded version of the BNC connector. It
helps resolve leakage and geometric stability problems, permitting
applications up to 12 GHz. The specifications for N, BNC and TNC connectors
are found in MIL-C-39012. There are special "extended frequency" versions of
the TNC that adhere to the IEC 169-17 specification for operation to 11 GHz
or 16 GHz, and the IEC 169-26 specification that operate mode-free to 18 Ghz
(but with significant losses). The TNC connector is in wide use in cellular
telephone RF/antenna connections. Because the mating geometries are
compatible with the N connector, it is possible to temporarily mate some
gender combinations of BNC and N. This is not a recommended use because the
connection is not mechanically stable, and there will be significant
impedance changes at the interface. 7/16 DIN  7.5 GHzThis relatively new
connector is finding popularity as an interconnect in cellular and other so
called "wireless" applications, especially on towers. The primary advantage
it has over N type connectors is that it uses a wrench to tighten.  It is
rated to 7.5 Ghz, uses rubber gaskets and silver or gold plate. GR874General
Radio (to old-timers, anyway), G874 same8.5 GHzGR874 connectors are sexless
(hermaphroditic), 50-ohm impedance connectors with a slide-on interface that
has been a standard for many years on a wide variety of test equipment, due
to its good electrical characteristics and ease of mating. These connectors
sometimes come with a locking interface for added mechanical security where
needed. Locking and non-locking interfaces are intermateable. GR900BT14 mm,
MPC14same8.5 GHz These sexless (hermaphroditic) connectors are often used in
highly critical laboratory applications at frequencies up to 8.5 GHz. C12
GHz C connectors are medium-size, 50-ohm impedance connectors with two-stud
bayonet coupling and good power handling capability, particularly those
connectors noted as high-voltage types. These are similar in size to type N
connectors, however, they are bayonet locking. The C series uses a Teflon
dielectric for its interface. The dielectric overlap enables better voltage
handling capabilities. The bayonet coupling does not perform well
electrically during vibration. Type N [image: Picture of Female and Male
Type N Connectors] [image: Picture of Female and Male Type N Connectors]12
GHz or more The Type N 50 ohm connector was designed in the 1940s for
military systems operating below 5 GHz. One resource identifies the origin
of the name as meaning "*N*avy". Several other sources attribute it to Mr.
Paul Neil, an RF engineer at Bell Labs. The Type N uses an internal gasket
to seal out the environment, and is hand tightened. There is an air gap
between center and outer conductor. In the 1960s, improvements pushed
performance to 12 GHz and later, mode-free, to 18 GHz. Hewlett Packard,
Kings, Amphenol, and others offer some products with slotless type-N outer
conductors for improved performance to 18 GHz. Type-N connectors follow the
military standard MIL-C-39012. Even the best specialized type-N connectors
will begin to mode around 20 GHz, producing unpredictable results if used at
that frequency or higher. A 75 ohm version, with a reduced center pin is
available and in wide use by the cable-TV industry. SMA3.5 mm or APC-3.5,
WSMA, 2.92 mm, K 12 GHz or moreThe SMA (Subminiature A) connector was
designed by Bendix Scintilla Corporation and is one of the most commonly
used RF/microwave connectors. It is intended for use on semi-rigid cables
and in components which are connected infrequently. It takes the cable
dielectric directly to the interface without air gaps. A few hundred
interconnect cycles are possible if performed carefully. Care should be
taken to join connectors straight-on. Prior to making a connection it is
wise to inspect the female end to assure that the center socket is in good
condition (fingers not bent or missing).

A standard SMA connector is designed for interconnects to 12.4 GHz.
Fortunately, a good SMA is usable to 18 GHz in most cables, and if well
constructed with greater loss and lower return loss to 24 GHz. Most SMA
connectors have higher reflection coefficients than other connectors
available for use to 24 GHz because of the difficulty to anchor the
dielectric support. Some manufacturers rate a special high quality version
of an SMA that meets SMA standards as high as 26.5 GHz (The Johnson Field
Replaceable SMA goes to 26.5 GHz, and the M/A-Com OSM extended frequency
series goes to 27 GHz). Because an SMA with such quality can be repeatably
manufactured, you will often see test equipment and components rated to
exactly 26.5 GHz with SMA connectors as the primary interconnect. "SMA"
connectors rated for frequencies higher than 27 GHz are really following
other standards and are made to be compatible with the SMA geometries to
allow mating with SMA. So called "precision SMA" connectors are available
with a variety of designators (e. g.,  3.5 & 2.92 mm). When two SMA
compatible connectors of different ratings are coupled, it is very likely
that the performance of the lesser connector will prevail.

Be advised that when mating a male SMA to a female "Precision SMA", to be
sure that the SMA male is of professional manufacture, and to insert the
male straight-on. If there is any doubt, it is wise to invest in an SMA
Connector Gauge, and gauge the SMA male prior to mating. This advice does
not apply to the connection of an SMA female to a 3.5 or 2.9 male. Such
connections do need to be made with care and straight-on.
APC-77 mm[image: Picture of an APC-7 connector] same18 GHzThe APC-7
(Amphenol Precision Connector - 7 mm) offers the lowest reflection
coefficient and most repeatable measurement of all 18 GHz connectors.
Development of this connector was a joint effort between HP and Amphenol
which began in the early 1960s. This is a sexless (hermaphrodite) design and
is the preferred connector for the most demanding applications, notably
metrology and calibration. These connectors are designed to perform
repeatably for thousands of interconnect cycles as long as the mating
surfaces are kept clean. You will find these connectors on the front of some
network analyzers. 2.4mm  50 GHzThe 2.4 mm connector was developed by HP,
Amphenol and M/A-COM for use to 50 GHz (the first waveguide mode is reached
at 52 GHz). M/A-Com refers to it as OS-2.4 (OS-50). This design eliminates
the fragility of the SMA and 2.92-mm connectors by increasing the outer wall
thickness and strengthening the female fingers. The inside of the outer
conductor is 2.4 mm in diameter, and the outside is 4.7 mm. Because they are
not mechanically compatible with SMA, 3.5-mm and 2.92-mm, precision adapters
are required in order to mate to those types. (This family is not directly
mateable with the SMA family.) The 2.4-mm product is offered in three
quality grades; general purpose, instrument, and metrology. General purpose
grade is intended for economy use on components, cables and microstrip,
where limited connections and low repeatability is acceptable. The higher
grades are appropriate for their respective applications.
------------------------------

*Torque for tightening connectors*
Connector type Torque lb-inch (N-cm)CommentPrecision 7mm12 (136)Finger tight
is acceptable Precision 3.5 mm & 2.92 mm 8 (90)When connecting SMA to 3.5
use torque for male connector SMA5 (56) When connecting SMA to 3.5
use torque for male connectorType N12 (136)Finger tight is acceptable

This page is based on material from
http://www.wa1mba.org/rfconn.htm, http://www.tm.agilent.com/,
http://www.connectronicsinc.com/,
http://www.vandenhul.com/other/c-connec.htm,http://www.deltarf.com/,
http://www.metas.ch/root_legnet/Web/Fachbereiche/Elektrizitaet/PDF%20Files/217/ConnectorBibliography1.4.pdf
,http://www.hparchive.com/Application_Notes/HP-Appnote-326.pdf,
http://www.vicom.com.au/downloads/MicrowaveConnectors.pdf,
http://www.mackie.com/support/Glossary/index.html and
http://www.maurymw.com/; certain web pages no longer in existence, and:

C. A. Harper (ed.), *Handbook of Wiring, Cabling, and Interconnecting for
Electronics*. New York: McGraw-Hill, 1972.

*The ARRL UHF/Microwave Experimenter's Manual.* Newington, CT: American
Radio Relay League, 1990.


  Edward F. Kuester
Department of Electrical and Computer Engineering
University of Colorado
December, 2007




Best 73 from: regards from: CT4RK Carlos Mourato - Sines - Portugal

 Save the Radio Spectrum! Eliminate Broadband over Power Line. Salve o
espectro electromagnético!. Não use a rede electrica para transmitir dados.
Os "homeplugs power line" e a tecnologia "power line" causa fortes
interferencias noutro serviços sem voce se aperceber. Diga não à tecnologia
power line. Proteja o ambiente
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