How to choose a double cone antenna for consistency testing
For many years, most of the regulatory standards require the use of half-wave dipole units for frequencies above 20 MHz. However, in order to reduce the test time, began to accept broadband antennas, such as a double cone antenna. The broadband antenna reduces the test time because the technician can adjust the even pole length for each of the frequencies of interest without stopping the test.
Double cooker is considered to be the main force of each compliant test laboratory standard. For a variety of applications, such as radiation emission, immunity and shielding efficiency testing; the antenna has proven to be a valuable asset. Double tapered antenna is also used in standardized site attenuation (NSA) measurements, site assessments (CISPR 16-1-4 SVSWR program) and spectrum monitoring applications.
Antenna characteristics
Double tapered antennas have several unique antenna features that can be separated from other antenna types. These linear polarized antennas are typically used for consistency tests within a frequency range of 20 MHz to 300 MHz.
Size and shape
The double tapered antenna is similar to the dipole antenna, except that they have a conical component. They also have integrated balance - unbalanced converters (balanced to imbalance) structures, which match components of the transmission line. Some balance-unbalanced converters are manufactured for high power capabilities for immunity testing. In most cases, these lightweight antennas have detachable components for easy storage.
Bandwidth
The antenna bandwidth is the total frequency range that the antenna can operate. One of the advantages of a double cone antenna is compact, covering a wide range of frequency bandwidth.
Antenna VSWR and reflection power
The antenna VSWR is the ratio of reflection power due to mismatch between antenna and the measurement system. A disadvantage of a double cylinder antenna is a poor VSWR, especially below 80 MHz. This is usually due to the limited dimensional requirements in MIL-STD 462, and can be overcome by selecting a larger element set. Another way to overcome this short decline is to add a 3 or 6 dB attenuator. This can increase the VSWR to 2: 1 or better.
Radiation map
The radiation pattern is a graph of the angular function of the antenna field with respect to the axis. The radiation pattern of the double cone antenna is similar to the half-wave dipole. They have a full direction in the H plane, and there is an eight graphic shape in the E plane. H Plateous Beam Width Drawings Make these antennas as an ideal choice for field surveys and spectrum monitoring.
Application
Double tapered antenna is used in various test applications. Its shape, power, and frequency range make it ideal for MIL-STD, FCC, CISPR, and other test specifications for the emission and immunity testing.
Radiometry
Radiation testing is the most common test type for consistency testing. It usually requires the field strength of the test device (EUT) in the 30 MHz to 1 GHz. For lower parts (30 MHz to 300 MHz).
Antisense test
The radiation immunity test requires the measured equipment to operate normally when irradiated with high electromagnetic energy. Double tapered antennas are typically performed within 80 MHz to 1 GHz frequency range, and those high magnetic fields can be generated within a lower frequency range of 20 MHz to 300 MHz, and 100 V / m can be generated at frequencies of 80 MHz to 300 MHz.
Shielding effect
The shielding housing is a metal structure of Faraday cage or grounding, preventing RF energy from entering the outer casing and leaking out. The shielding effect of these outer casings requires a double cone antenna.
Evaluation test location
The test site is a measuring device that should be re-authenticated regularly. Verification of test sites typically requires using a duplete antenna according to ANSI C63.4. The double cone antenna meets the evaluation of the normalized site attenuation measurement as high as 300 MHz and 1GHz.
Spectrum monitoring
Spectrum monitoring or radio monitoring covers a wide range of work. Double cooker is ideal for such applications due to its wide range of workout and full mode.
Source: AHS
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