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 Newsletter
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June 2002 edition of the Amphenol RF Connection v 1.4
In this issue:
Amphenol Provides Multiple Connector Lines for Base Station Market
Amphenol Introduces New QMA Connector Line
Dave’s Q & A: How can I be sure a PCB connector will perform when mounted on my design?
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Amphenol Provides Multiple Connector Lines for Base Station Market
Every day millions of people rely on cell phones and other wireless devices for communication. In order to facilitate uninterrupted services
base stations play a key role. Base Stations are the link between wireless devices and the rest of the world. While many people would
recognize the large cellular towers on the roadside as base stations, there are also smaller, lower power base stations for indoor wireless
applications. Base stations transmit wireless signals to hand held devices using signal amplifiers, and also receive transmissions back from
those same devices through sensitive receivers.
Base stations serve several crucial functions to ensure successful communication and are critical in ensuring the uninterrupted flow of data
to and from a wireless device. First it must transmit the appropriate information to the appropriate device, which can often be miles away.
Secondly it must clearly receive the small signals generated by the wireless device, which often means attenuating and then filtering the signal
from ambient noise. Thirdly, depending on the nature of the wireless network, the base station must relay transmissions towards their final
destination.
To accomplish this, base stations make use of a complicated series of narrow pass band filters, power amplifiers, low noise amplifiers, splitters,
combiners and signal attenuators. The largest base stations use a complicated array of these components to provide the uninterrupted, high
quality service their customers require. Those components, often supplied by several different subcontractors, must be tied together. That is
where Amphenol RF’s connectors come into play. Cable assemblies, utilizing RF connectors, jumper together the various components to carry
transmissions from one point to the next.
Traditional interconnect techniques utilized threaded SMA’s to interconnect components. Today more and more companies are turning towards Amphenol
RF’s line of 1.0/2.3 and QMA quick connect/posi-lock connectors. Traditional threaded connectors provide excellent performance but at a cost.
Threading the mates together is a time consuming process, especially in larger stations. Additionally threaded connectors require more space to
allow wrenches room to provide adequate torque.
QMA and 1.0/2.3 connectors significantly reduce the time required per mating and provide excellent performance in the frequency ranges used in base
station applications. Snap on connectors allow for more connectors per area than threaded SMAs and, with the posi-lock design, a secure mating.
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Amphenol Introduces New QMA Connector Line
Amphenol RF introduces a new line of QMA connectors that can replace SMA connectors in most applications and offer similar
performance but with much improved efficiency of installation. The QMA connector is a quick disconnect version of the SMA
connector and shares the internal construction, which allows the connector to have excellent performance. The benefits of
the connectors are both electrical and mechanical.
The electrical performance benefits of these connectors include low loss RF performance up to 6 GHz. Because of the innovative
coupling mechanism, a 360-degree butt joint is maintained which results in low RF leakage. Since the RF line is identical to the
SMA series, the QMA connectors also offer the same high power handling capability. This gives the series significant advantages
over other quick disconnect connectors.
Mechanically the QMA series offers an advantage over SMA connectors in the installation. Because the interface mates with a
snap-on instead of a threaded coupling, there is a significant time advantage. Typically, these connectors can be installed
into a system 10 times faster than an SMA connector. Another benefit of eliminating the threaded coupling is the denser packaging.
The pitch between connector can be reduced because there is no requirement for wrench clearance. Finally, the connectors can be
rotated 360 degrees after they are mated which greatly improves the flexibility of installations.
The Amphenol QMA product line is growing quickly and currently includes configurations for semi-rigid and PC board applications.
Please contact us for more information about the
entire product line or to discuss specific configuration requests.
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Q: How can I be sure a PCB connector will perform when mounted on my design?
A: When designing surface mount or PC style connectors, the connector manufacturer generally does not
know on what type of environment the connector will be launched. The connector is designed as a coaxial device
and its performance is optimized using High Frequency Structure Simulator (HFSS) software. However, depending on
the type of PC board (microstrip, stripline, coplanar, etc.), and board parameters (dielectric constant, thickness,
trace width, etc.), different compensation schemes will be necessary at the launch because a discontinuity
capacitance is introduced at the point of launch, and it can severely degrade system performance.
At Amphenol RF, we use ANSOFT HFSS to model a connector on a customer's PCB. After simulating the performance and
examining the frequency and time domain results, we make changes to the pads and/or trace to achieve a better
broadband impedance match. We will then advise the customer as to what changes will result in optimum performance.
The connector above is shown mounted on a microstrip board. There is no compensation, and the Return Loss for the uncompensated
launch is -20 dB and the Insertion Loss is -.04 dB. The Time Domain shows a capacitance at the launch, so additional inductance
must be added to compensate.
Several different configurations can be simulated in a matter of minutes, and the changes recommended result in a Return loss of
-35 dB (a 15 dB improvement) and a decrease in Insertion Loss from -.04 dB to less than -.01 dB.
This is an example of the types of services Amphenol offers to our customers that help design better products.
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