User manual

26
Subject to change without notice
General informations General informations
General informations
Electromagnetic compatibility continues to be an
important issue. The main goal is to make circuitry
„quieter“ and more sustainable to meet tough
EMC regulations. Even with the best PCB layout
techniques and the most substantial decoupling,
at the speeds of today’s designs, radiation from
boards and the consequent noise impinging on
PCBs is becoming a growing problem that will
not go away.
In order to minimize the cost of test to comply
with EMC regulations, it is recommended that
a “Pre-Compliance” phase in product develop-
mentrst to be conducted.This phasewould
use a spectrum analyzer such as the HM5014 or
HM5530 in conjunction with HZ540 or HZ550 near
eldsnifferprobes,toinspectforemissionand
leakage, isolate the source, redesign and correct
the problem and then retest.
Once the product appears electromagnetically
“quiet”,itissubmittedtothecompliancecerti-
cation laboratory. This should save the expense
for much of the test time, since the submitted unit
has already been pretested. Typically, the test time
and money saved should represent many times the
purchase price of the spectrum analyzer.
HZ540 and HZ550
EMI-Near Field Probe Sets
The HZ540/550 are the ideal toolkits for the
investigationofRFelectromagneticelds.They
are indispensable for EMI pre-compliance testing
during product development, prior to third party
testing. The sets include 3 resp. 5 hand-held
probeswithbuilt-inpre-ampliercoveringthe
frequency range from
<1MHz to approx. 3000
MHz.
The probes of the basic set HZ540 include one
magneticeldprobe,oneelectriceldprobe,
and a high impedance probe. In addition to it the
HZ550featuresanoptionalµ-magneticeldprobe
and a passive radiation probe. All probe outputs
are matched to the 50 Ohm inputs of spectrum
analyzers or RF-receivers.
The probes are designed to assist in providing
quick identication of signal sources. It can be
used to diagnose emissions from circuit boards,
integrated circuits, PC board edge runs, ground
plane currents, ribbon cables, corner seams and
similar interference sources.
Signal feed is via a 1.2m SMA to N-connector
cable. When used in conjuction with a spectrum
analyzer or a measuring receiver, the probes can
be used to locate and qualify EMI sources, as well
as evaluate EMC prob lems at the breadboard and
prototype level. They enable the user to evaluate
radiatedeldsandperformshieldeffectiveness
comparisons. Mechanical screening performance
and immunity tests on cables and components are
easily performed.
Electric-Field Probe HZ551
The electric field (mono-pole) probe has the
highest sensitivity of all probes in the HZ540/550
sets. It can be used to check shielding and per-
form pre-compliance testing on a comparative
basis. It is even sensitive enough to be used as
an antenna for radio or TV reception. With this
probe the entire radiation from a circuit or an
equipment under test can be measured. It is
used, for example, to determine the effectiveness
of shielding measures. The effect of suppression
„xes“can be quicklyveried. Theprobe may
be used to perform relative measurements for
certification tests. This makes it possible to
apply remedial suppression measures so that
any requalication results will bepositive. In
addition,pre-testingforcerticationtestsmaybe
performed so that no surprises are encountered
duringthecerticationtests.
Magnetic-Field Probe HZ552
The radiated signals detected with the E-Field
probe can be further investigated by menas of
themagneticeldprobeHZ552.Themagnetic
probe incorporates a high degree of rejection
of both stray and direct electric fields, and
provides far greater repeatability than with
conventional field probes. Measurements
can be made on the very neareld area that
is close to components or radiation sources.
It is especially suited to locate emission “hot
spots” on PCBs and cables. One can investigate
shields for “leaking” areas and cables or wires
for conducted interference. With this probe, the
entireeffectivenessoflterscanbemeasured
by measuring the RFI which is conducted along
cablesthatleavetheequipmentandmayinu-
ence the total radiation.