ARLA/CLUSTER: Perdas nos conectores???

[Antonio Matias]

Boas.
O problema é sempre o mesmo.
Gastamos quantias consideráveis em transceptores e antenas e depois gastamos
50 Centimos numa PL-259 chinesa.
Achamos que dar 3Euros de qualidade é um exagero.
Hoje em dia há PL.259 de boa qualidade, com corpo metálico semelhante ás
fichas N e dieléctrico em Teflon.
Acredito que essas fichas possam ir até UHF sem problemas de maior.
Qualquer das formas, a ficha N, deve ser a preferencial acima dos  30Mhz.

73
Matias


2010/7/17 Carlos Mourato <radiofarol  gmail.com>

> 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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