->  TW>  The mismatch damage is a prolbem with higher powered transmitters. I
-> highly doubt a 802.11 transmitter would be hurt.

-> Am I right then to assume that increasing the length of the cable will also
-> help reduce that risk? 

-> At the moment 20' only gives me a very limited choice of location for the
-> antenna, and I am beginning to suspect that at 50' I will loose more to
-> line-loss than I would gain from a more advantageous location.

 You are correct on that one unless you buy VERY expensive cable. And
even then the losses are very high. 3 db is about 33% signal loss and
at 2.4 GHz I see losses arround 15 db for some very good cable and over
20 db for the cheaper stuff. That of course is per 100 Foot of cable.


-> What problems might I encounter if I artfully bared and clamped the cable in
-> place, eliminating the need for a connector at the antenna completely?

At those frequencies clamping is not a good Idea. Any distortion of the
Ground Braid to Center conducter geometry will create signal loss
basicly. 

As a side note on Connectors here is some data I dug up. NOTE that the
PL 259 is marginal at 200 Mhz. 
The BNC even has some problems. I would lean toward the SMR fitting but
the TNC(a BNC that threads on instead of twist locks) would work.



UHF CONNECTOR PL259 GOLD TIP, TELFON INSULATOR

This UHF-MALE (PL259) connector is silver plated, with a tapered gold
tip, teflon Insulation and heavy duty knurling. The uhf connector is
1.56" long with a .72" dia. This UHF-MALE (PL259) connector is a low
cost general purpose connector for use on small and medium size coaxial
cables .199" to .432" outer diameter. They perform satisfactory up to
200MHZ, and usable with caution up to 500MHZ.  


----------------------------------------------------------------------

Type N 

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 "Navy". 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. 

---------------------------------------------------------------------

BNC and TNC 
 
The "Bayonet Neil-Concelman" 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. 

A threaded version (TNC) 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
specificaion 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. 



---------------------------------------------------------------------

SMA 
 
The SMA (Subminiature A) connector was designed by Bendix Scintilla
Corporation and Omni-Spectra Corporation as the OSM connector, 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 useable 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 Replacable 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. 







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