Over-the-air (OTA) testing fundamentals...Area of planar wave distribution with defined amplitude...
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Area of planar wave distribution with defined amplitude taper and ripple Definition of Fraunhofer distance Quiet zone phase deviation and magnitude error Quiet zone (D) –D/2 +D/2 ∆d R R φ(R) φ(R+d) –20 dB –25 dB –30 dB R FFmin (N) D 2 /λ 2D 2 /λ 4D 2 /λ 8D 2 /λ Phase deviation (φ) 45° 22.5° 11.2° 5.6° High gain antenna pattern Power R FFmin = ND 2 λ N = 1 N = 2 N = 4 N = ∞ The Fraunhofer distance presents the best compromise between a compact test setup, acceptable phase deviation and measurable null Parameters to consider for quiet zone size and quality Example of amplitude/phase taper Example of amplitude/phase ripple Quiet zone for 1 dB taper 1 dB taper or 10° phase Ripple around taper (±0.5 dB) Software based near-field to far-field transformation Fourier transform – requires phase and magnitude measurement Complex wave: phase and magnitude measurement Fourier transform: software based Far field: generated Near-field (E-field) surface measurement methods Cylindrical Planar Spherical f x,y = A∫∫ E x,y e +jk∙r dxdy E-field E-field b a Hardware-based near-field to far-field transformation Planar wave distribution – indirect far-field (IFF) Complex near-field wave generated Planar wave distribution: hardware-based Plane wave, far-field received f x,y = A∫∫ E x,y e +jk∙r dxdy E-field DUT Quiet zone Quiet zone Quiet zone Lens Reflector PWC DUT DUT Plane wave converter (PWC) Fresnel lens (Fourier optics) Reflector: compact antenna test range (CATR) Amplitude Phase R = 1.5 m 1.0 m 1.8 m For more information: Near-field definitions Boundary from reactive to radiated near field for radiators with D > λ/2: 3 0.62 NF D R λ = ⋅ 9 5 1 21 17 13 25 Antenna aperture size D (cm) Distance (m) 1.00 0.75 0.50 0.25 0.00 39 GHz 28 GHz 9 5 1 21 17 13 25 Antenna aperture size D (cm) Fraunhofer distance (m) 20 15 10 5 0 39 GHz 28 GHz The Fraunhofer distance describes the boundary between the near field and far field: 2 2 FF D R λ = Over-the-air (OTA) testing fundamentals Most compact OTA test solutions for antenna and device testing www.rohde-schwarz.com/5G All objects become part of the antenna system and interfere with RF measurements. Up to 10 GHz the specific absorption rate (SAR) is typically measured in this region. Reactive near-field region How to perform far-field measurements at near-field distances Radiated near-field region (requires phase and magnitude measurement) Far-field region (requires magnitude measurement only) Far-field measurements Far-field measurements are fast and simple and provide higher measure- ment reliability, but path loss is higher and the test setup becomes larger with increasing DUT size and higher frequencies. Typical far-field measurements for device characterization ❙ TRP, EIRP, ACLR ❙ Error vector magnitude (EVM) ❙ Spectrum ❙ Power ❙ Block error rate (BLER) Far-field quiet zone This method is generally not suitable for metrics such as EVM and ACLR due to their time dependencies. The ripple value impacts measurement accuracy. Size of achievable quiet zone depends on the taper value. Near-field measurements The test setup for near-field measurements is compact, but measurements are complex, time-consuming and have higher uncertainty. Typical near-field measurements for device characterization ❙ Total radiated power (TRP) ❙ Peak equivalent isotropic radiated power (EIRP) ❙ Adjacent channel leakage ratio (ACLR) Aperture size D R&S®PWC200 plane wave converter PWC bandwidth: min. frequency depends on antenna resonance max. frequency depends on antenna spacing R&S®ATS800B benchtop CATR CATR bandwidth: min. frequency depends on reflector edge treatment max. frequency depends on reflector surface roughness
Transcript of Over-the-air (OTA) testing fundamentals...Area of planar wave distribution with defined amplitude...
Area of planar wave distribution with defined amplitude taper and ripple
Definition of Fraunhofer distance Quiet zone phase deviation and magnitude error
Quiet zone (D)
–D/2
+D/2∆d
R
R
φ(R)
φ(R+d)
–20 dB
–25 dB
–30 dB
RFFmin (N)
D2/λ
2D2/λ
4D2/λ
8D2/λ
Phase deviation (φ)
45°
22.5°
11.2°
5.6°
High gainantenna pattern
Pow
er
RFFmin =ND2
λ
N = 1
N = 2
N = 4
N = ∞
The Fraunhofer distance presents the best compromise between a compact test setup, acceptable phase deviation and measurable null
Parameters to consider for quiet zone size and quality
Example of amplitude/phase taper Example of amplitude/phase ripple
Quiet zone for 1 dB taper
1 dB taper or10° phase
Ripple aroundtaper (±0.5 dB)
Software based near-field to far-field transformation
Fourier transform – requires phase and magnitude measurement
Complex wave: phase and magnitude measurement Fourier transform: software based Far field: generated
Near-field (E-field) surface measurement methods
Cylindrical Planar Spherical
fx,y = A∫∫ Ex,ye+jk∙rdxdy
E-field
E-field
b
a
Hardware-based near-field to far-field transformation
Planar wave distribution – indirect far-field (IFF)
Complex near-field wave generated Planar wave distribution: hardware-based Plane wave, far-field received
fx,y = A∫∫ Ex,ye+jk∙rdxdy
E-field
DUT
Quiet zoneQuiet zone Quiet zone
Lens Reflector PWC
DUT DUT
Plane wave converter (PWC)Fresnel lens (Fourier optics) Reflector: compact antenna test range (CATR)
Amplitude Phase
R = 1.5 m
1.0 m
1.8 m
For more information:
Near-field definitions
Boundary from reactive to radiated near field for radiators with D > λ/2:
3
0.62NFDRλ
= ⋅
951 211713 25
Antenna aperture size D (cm)
Dist
ance
(m)
1.00
0.75
0.50
0.25
0.00
39 GHz
28 GHz
951 211713 25
Antenna aperture size D (cm)
Frau
nhof
er d
ista
nce
(m)
20
15
10
5
0
39 GHz
28 GHz
The Fraunhofer distance describes the boundary between the near field and far field:
22FF
DRλ
=
Over-the-air (OTA) testing fundamentals
Most compact OTA test solutions for antenna and device testing
www.rohde-schwarz.com/5G
All objects become part of the antenna system
and interfere with RF measurements. Up to
10 GHz the specific absorption rate (SAR) is
typically measured in this region.
Reactive near-fi eld region
How to perform far-fi eld measurements at near-fi eld distances
Radiated near-fi eld region (requires phase and magnitude measurement) Far-fi eld region (requires magnitude measurement only)
Far-fi eld measurementsFar-field measurements are fast and simple and provide higher measure-ment reliability, but path loss is higher and the test setup becomes larger with increasing DUT size and higher frequencies.
Typical far-field measurements for device characterization ❙ TRP, EIRP, ACLR ❙ Error vector magnitude (EVM) ❙ Spectrum ❙ Power ❙ Block error rate (BLER)
Far-fi eld quiet zone
This method is generally not suitable for metrics such as EVM and ACLR due
to their time dependencies.
The ripple value impacts
measurement accuracy.
Size of achievable
quiet zone depends
on the taper value.
Near-fi eld measurementsThe test setup for near-field measurements is compact, but
measurements are complex, time-consuming and have higher
uncertainty.
Typical near-field measurements for device characterization ❙ Total radiated power (TRP) ❙ Peak equivalent isotropic radiated power (EIRP) ❙ Adjacent channel leakage ratio (ACLR)
Aperture size D
R&S®PWC200 plane wave converterPWC bandwidth: min. frequency depends on antenna resonancemax. frequency depends on antenna spacing
R&S®ATS800B benchtop CATRCATR bandwidth: min. frequency depends on refl ector edge treatmentmax. frequency depends on refl ector surface roughness
Over-the-air_testing_fundamentals_po_5216-4162-82___5216-4179-82_v0100.indd 1 12.02.2019 11:34:33
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Over-the-air (OTA) testing fundamentals
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Over-the-air (OTA) testing fundamentals
Area of planar wave distribution with defined amplitude taper and ripple
Definition of Fraunhofer distance Quiet zone phase deviation and magnitude error
Quiet zone (D)
–D/2
+D/2∆d
R
R
φ(R)
φ(R+d)
–20 dB
–25 dB
–30 dB
RFFmin (N)
D2/λ
2D2/λ
4D2/λ
8D2/λ
Phase deviation (φ)
45°
22.5°
11.2°
5.6°
High gainantenna pattern
Pow
er
RFFmin =ND2
λ
N = 1
N = 2
N = 4
N = ∞
The Fraunhofer distance presents the best compromise between a compact test setup, acceptable phase deviation and measurable null
Parameters to consider for quiet zone size and quality
Example of amplitude/phase taper Example of amplitude/phase ripple
Quiet zone for 1 dB taper
1 dB taper or10° phase
Ripple aroundtaper (±0.5 dB)
Software based near-field to far-field transformation
Fourier transform – requires phase and magnitude measurement
Complex wave: phase and magnitude measurement Fourier transform: software based Far field: generated
Near-field (E-field) surface measurement methods
Cylindrical Planar Spherical
fx,y = A∫∫ Ex,ye+jk∙rdxdy
E-field
E-field
b
a
Hardware-based near-field to far-field transformation
Planar wave distribution – indirect far-field (IFF)
Complex near-field wave generated Planar wave distribution: hardware-based Plane wave, far-field received
fx,y = A∫∫ Ex,ye+jk∙rdxdy
E-field
DUT
Quiet zoneQuiet zone Quiet zone
Lens Reflector PWC
DUT DUT
Plane wave converter (PWC)Fresnel lens (Fourier optics) Reflector: compact antenna test range (CATR)
Amplitude Phase
R = 1.5 m
1.0 m
1.8 m
For more information:
Near-field definitions
Boundary from reactive to radiated near field for radiators with D > λ/2:
3
0.62NFDRλ
= ⋅
951 211713 25
Antenna aperture size D (cm)
Dist
ance
(m)
1.00
0.75
0.50
0.25
0.00
39 GHz
28 GHz
951 211713 25
Antenna aperture size D (cm)
Frau
nhof
er d
ista
nce
(m)
20
15
10
5
0
39 GHz
28 GHz
The Fraunhofer distance describes the boundary between the near field and far field:
22FF
DRλ
=
Over-the-air (OTA) testing fundamentals
Most compact OTA test solutions for antenna and device testing
www.rohde-schwarz.com/5G
All objects become part of the antenna system and interfere with RF measurements. Up to 10 GHz the specific absorption rate (SAR) is typically measured in this region.
Reactive near-fi eld region
How to perform far-fi eld measurements at near-fi eld distances
Radiated near-fi eld region (requires phase and magnitude measurement) Far-fi eld region (requires magnitude measurement only)
Far-fi eld measurementsFar-field measurements are fast and simple and provide higher measure-ment reliability, but path loss is higher and the test setup becomes larger with increasing DUT size and higher frequencies.
Typical far-field measurements for device characterization❙ TRP, EIRP, ACLR❙ Error vector magnitude (EVM)❙ Spectrum❙ Power❙ Block error rate (BLER)
Far-fi eld quiet zone
This method is generally not suitable for metrics such as EVM and ACLR due
to their time dependencies.
The ripple value impacts
measurement accuracy.
Size of achievable
quiet zone depends
on the taper value.
Near-fi eld measurementsThe test setup for near-field measurements is compact, but measurements are complex, time-consuming and have higher uncertainty.
Typical near-field measurements for device characterization❙ Total radiated power (TRP)❙ Peak equivalent isotropic radiated power (EIRP)❙ Adjacent channel leakage ratio (ACLR)
Aperture size D
R&S®PWC200 plane wave converterPWC bandwidth: ❙ min. frequency depends on antenna resonance❙ max. frequency depends on antenna spacing
R&S®ATS800B benchtop CATRCATR bandwidth: ❙ min. frequency depends on reflector edge treatment❙ max. frequency depends on reflector surface roughness
Over-the-air_testing_fundamentals_po_5216-4162-82_v0100.indd 1 11.02.2019 14:52:31
Over-the-air_testing_fundamentals_po_5216-4162-82___5216-4179-82_v0100.indd 2 12.02.2019 11:34:38
