1、 MIL-STD-220C14 May 2009 SUPERSEDING MIL-STD-220B24 January 2000 DEPARTMENT OF DEFENSE TEST METHOD STANDARD METHOD OF INSERTION LOSS MEASUREMENT AMSC N/A FSC EMCS INCH-POUND Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-STD-220C ii FOREWORD 1.
2、This standard is approved for use by all Departments and Agencies of the Department of Defense. 2. This standard specifies a method of measuring the filtering capabilities of passive, low-pass, electromagnetic interference (EMI)/radio-frequency interference (RFI) filters as a function of frequency a
3、nd considering the influence of temperature and direct current bias. This measurement is known as insertion loss (IL). 3. Filters measured by this method are typically feed-through types, having the live conductor(s) passing through the filter providing both input and output terminals protruding fro
4、m and insulated from the case which acts as the ground terminal. These filters typically contain capacitors only or capacitors and inductors, and may also contain resistors or diodes. The filters measured to this standard are normally designed for bulkhead mounting, where the input and output termin
5、als are completely isolated from each other by the bulkhead. 4. The test methods in this standard are intended to provide data for quality control during quantity production of filters. The test methods specified with 50 ohm input and output terminations are satisfactory for this purpose; but do not
6、 represent conditions that exist in actual circuits or installations. In general, there is little correlation between the MIL-STD-220 quality control tests and the performance of a filter in a particular application. This is because power line filters are normally used under conditions where the pow
7、er source and load impedances are independent of each other and can vary widely as a function of frequency. In addition, the power source impedance varies from line to line in general practice. 5. Beneficial comments (recommendations, additions, deletions) and any pertinent data which may be of use
8、in improving this document should be addressed to: Defense Supply Center Columbus, Attn: DSCC-VAT, Post Office Box 3990, Columbus, OH 43218-3990, or emailed to capacitorfilterdscc.dla.mil. Since contact information can change, you may want to verify the currency of this address information using the
9、 ASSIST online database at http:/assist.daps.dla.mil. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-STD-220C iii CONTENTS PARAGRAPH PAGE FOREWORD ii 1. SCOPE 1 1.1 Scope 1 2. APPLICABLE DOCUMENTS 1 2.1 General 1 2.2 Government documents 1 2.2.1
10、 Specifications, standards, and handbooks 1 2.3 Order of precedence. 1 3. DEFINITIONS. 2 3.1 Insertion loss 2 4. GENERAL REQUIREMENTS. 3 4.1 Test setup 3 4.1.1 Shielding test. 3 4.2 Test equipment . 3 4.2.1 Output signal. 3 4.2.1.1 Measuring a filter. 3 4.2.1.2 Error correction for accurate passband
11、 measurements. 3 4.2.1.3 Sources and types of errors 5 4.2.2 Coaxial lines, connectors, and switches 5 4.2.3 Isolation attenuators. 5 4.2.4 RF-dc insertion loss measuring equipment assembly. 5 4.2.5 Standard attenuator 5 5. METHOD OF TEST 8 5.1 Test conditions 8 5.2 Test procedure 8 5.2.1 Preliminar
12、y operation 8 5.2.2 Method of measurement 8 6. NOTES. 9 6.1 Intended use 9 6.2 Subject term (key word) listing. 9 6.3 Changes from previous issue 9 APPENDIX A - Analysis of Filter Measurements. 10 A.1 Discussion 10 A.1.1 Elements 10 A.1.2 Details 10 A.2 Test condition. 11 Provided by IHSNot for Resa
13、leNo reproduction or networking permitted without license from IHS-,-,-MIL-STD-220C iv CONTENTS - Continued FIGURE PAGE 1. Basic test circuit 4 2. Measuring Filter Insertion Loss 6 3. Insertion loss good ground and good connection to test fixture 7 A-1. Insertion loss good filter and shell ground .
14、11 A-2 Insertion loss poor filter ground to shell 12 A-3 Insertion loss poor filter and fixture ground 13 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-STD-220C 1 1. SCOPE 1.1 Scope. This standard covers a method of measuring, in a 50 ohm syste
15、m, the insertion loss of feed-through suppression capacitors, and of single and multiple circuit radio frequency (RF) filters at frequencies up to 10 gigahertz (GHz). 2. APPLICABLE DOCUMENTS 2.1 General. The documents listed in this section are specified in sections 3, 4, and 5 of this standard. Thi
16、s section does not include documents cited in other sections of this standard or recommended for additional information or as examples. While every effort has been made to ensure the completeness of this list, document users are cautioned that they must meet all specified requirements documents cite
17、d in sections 3, 4, and 5 of this standard, whether or not they are listed. 2.2 Government documents. 2.2.1 Specifications, standards, and handbooks. The following specifications, standards, and handbooks form a part of this document to the extent specified herein. Unless otherwise specified, the is
18、sues of these documents are those listed in the solicitation or contract. DEPARTMENT OF DEFENSE SPECIFICATIONS MIL-DTL-17 - Cables, Radio Frequency, Flexible and Semi-rigid, General Specification For. MIL-PRF-39012 - Connectors, Coaxial, Radio Frequency, General Specification For. (Copes of these do
19、cuments are available online at http:/assist.daps.dla.mil/quicksearch/ or from the Standardization Document Order Desk, 700 Robbins Avenue, Building 4D, Philadelphia, PA 19111-5094.) 2.3 Order of precedence. Unless otherwise noted herein or in the contract, in the event of a conflict between the tex
20、t of this document and the references cited herein, the text of this document takes precedence. Nothing in this document, however, supersedes applicable laws and regulations unless a specific exemption has been obtained. Provided by IHSNot for ResaleNo reproduction or networking permitted without li
21、cense from IHS-,-,-MIL-STD-220C 2 3. DEFINITIONS 3.1 Insertion loss. At a given frequency, the insertion loss of a feed through suppression capacitor or a filter connected into a given transmission system is defined as the ratio of voltages appearing across the line immediately beyond the point of i
22、nsertion, before and after insertion. As measured herein, insertion loss is represented as the ratio of input voltage required to obtain constant output voltage, with and without the component, in the specified 50 ohm system. This ratio is expressed in decibels (dB) as follows: 21EElog20lossInsertio
23、n = Where: E1= The output voltage of the network/spectrum analyzer with the component in the circuit. E2= The output voltage of the network/spectrum analyzer with the component not in the circuit. When testing is conducted with a network/spectrum analyzer, the equipment usually maintains a constant
24、output voltage and can be set to record the output to input voltage ratio in decibels. NOTE: The network/spectrum analyzer will provide a direct reading of loss. There is no need to do any conversion of voltage readings. Provided by IHSNot for ResaleNo reproduction or networking permitted without li
25、cense from IHS-,-,-MIL-STD-220C 3 4. GENERAL REQUIREMENTS 4.1 Test setup (no load). The test circuit shall be arranged as shown on figure 1 using a network or spectrum analyzer. The test setup shall be capable of indicating a repeatable insertion loss within 1.0 dB over the required frequency range.
26、 All test equipment shall be well shielded, and shall be filtered to the extent that leakage, either conducted or radiated, shall not affect the output level and sensitivity, respectively, needed to make the required maximum insertion loss measurement, see section 5 (method of test) for details. 4.1
27、.1 Test setup (with load): To measure the insertion loss of a filter under conditions of load, current, or voltage, the DUT shall be isolated from the network analyzer with the use of dc blocking capacitors. A pair of appropriate LC networks will be connected to the DUT to inject the dc current or d
28、c voltage into the filter. Normalization of the instrument, with the dc load applied will be completed through the frequency range of interest prior to making any measurements. Caution: The direct current (dc) source used in making insertion loss measurements with full load applied shall be a floati
29、ng dc source and shall not be connected to ground. 4.1.2 Shielding test. Set up the equipment for the filter out condition of insertion loss measurement (see 5.2.2). The test setup shall then be connected for the filter in condition by substituting for the component, a solid brass or copper plate at
30、 least .25 inch thick (6.35 mm) with plane faces at least 2.38 inches (60.45 mm) wide in all directions. This plate shall be placed across the coupler and center conductor of the measuring equipment assembly so that the signal source and load are completely short circuited by the faces of the plate.
31、 The insertion loss shall be at least 80 dB greater than the insertion loss to be measured. 4.2 Test equipment. 4.2.1 Output signal. Any instrument selected for measurement shall be capable of maintaining an output signal that is within 1 percent of nominal over a 2 minute period. 4.2.1.1 Measuring
32、a filter. Complete characterization of filters is typically achieved with sweep-frequency measurements. The most commonly measured filter characteristics are insertion loss and bandwidth. Another common measured parameter is out-of-band rejection. This is a measure of how well a filter passes signal
33、s within its bandwidth while simultaneously rejecting signals well outside that same bandwidth. 4.2.1.2 Error correction for accurate passband measurements. Variation from a constant amplitude response within the filters bandwidth results in signal distortion. Error correction is often essential for
34、 accurate measurements of filter pass bands. When a filters pass band is measured with a network analyzer without calibration, the response may vary considerably, depending on the network analyzer and test cables used. When the same filter is evaluated after doing a response calibration (normalizati
35、on), the test systems transmission-tracking frequency-response error is removed from the measured response, resulting in a much narrower amplitude-distortion window. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-STD-220C 4 FIGURE 1. Basic test
36、circuit. NOTE: All cables are 50 ohm double shielded. The cables are suitable for the application and terminated in SMA (subminiature version A connector) style connectors. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-STD-220C 5 4.1.2.3 Source
37、s and types of errors. a. Systemic errors Systemic errors are caused by imperfections in the test equipment and test setup. If these errors do not vary over time, they can be characterized through calibration and mathematically removed during the measurement process. b. Random errors. Random errors
38、vary as a function of time. Since they are not predictable, they cannot be removed by calibration. c. Drift errors Drift errors occur when a test systems performance changes after a calibration has been performed. They are primarily caused by temperature variation and can be removed by additional ca
39、libration. By constructing a test environment with stable ambient temperature, drift errors can usually be minimized. These situations are listed for reference only, it is expected that the test agency will select appropriate equipment that is capable of performing the test and has the stability to
40、have a reading repeatability of 1dB made on the same filter at the same time, temperature and frequency conditions as the first reading. 4.2.2 Coaxial lines, connectors, and switches. All coaxial lines shall be RG-214/U, or equivalent double shielded cable, and shall conform to MIL-DTL-17. It is ess
41、ential that cable with the characteristic impedance of type RG-214/U be used to connect the isolation attenuators together for the filter out condition and to connect the component to the isolation attenuators for the filter in condition. The length of cable connecting the isolation attenuators for
42、the filter out condition shall be within 6 inches (152.4 mm) of the combined length of the two cables connecting the component to the isolation attenuators for the filter in condition. Type N, SMA or equivalent RF 50 ohm coaxial connectors conforming to MIL-PRF-39012 shall be used where applicable.
43、When coaxial switches are used, they shall have a 50 ohm characteristic impedance, and a maximum voltage standing wave ratio (VSWR) of 1.1 to 1 at the frequency of measurement. 4.2.3 Isolation attenuators. Isolation attenuators are not necessary when testing is conducted using a network/system analy
44、zer that has a 50 ohm input and output ports. 4.2.4 Insertion loss measurement. When the component under test has no provisions for coaxial connections, the insertion loss measurements shall be recorded after the components input and output terminals are surrounded by RF shielding that has a common
45、electrical connection with the shielding of the test equipment or test equipment cables. Use adequate clamping means on the isolation fixture when using a network/spectrum analyzer (see figure 2 and figure 3). 4.2.5 Standard attenuator. A standard attenuator for testing with network/spectrum analyzer shall be provided with the following characteristics: a. Attenuation of 50 0.5 dB over the frequency range of 150 kHz to 1,000 MHz, inclusive. b. Maximum VSWR of 1.2 to 1 over the frequency range of 150 kHz to 1,000 MHz, inclusive. c. Input and output impedance of 50
