How to select the correct RF amplifierExample estimation of the required power for a requested field strength of 10 V/m in the desired frequency range

Cables, connector,filter, switches

–1.5 dB 1) + 9 dB

Antenna gain Field uniformity

– 6 dB 3)43 dBm =

P–1 dB – Power

0 dBm

Signal generators 3 m test distance

E = √ˉˉˉˉˉ30×P––––

d

Directonal coupler

– 0.3 dB

2)

1) Harmonics in the field must be below 6 dBc, filters are typically not required.2) This formula does not cover influences from chamber or test setup. An additional margin may be useful.3) Field uniformity needs up to 6 dB more amplifier power (for a single measurement point).

❙ The test distance between antenna and uniform field area has to include the distance to the antenna phase center.

❙ According to IEC/EN 61000-4-3 the amplifier must be operated below its 2 dB compression point. Due to amplifier variation the 1 dB compression point should be selected for the estimation.

The uniform field area (UFA)IEC/EN 61000-4-3 field calibration

150 cm

150 cm

Measurementpoints 80 cm

D = 1 m to 3 m

Uniform field area

Anechoicchamber

Uniform field area (UFA) criteria ❙ Size: 1.5 m × 1.5 m ❙ –0 dB/+6 dB variation over UFA plane ❙ More than 75 % of points have to be within tolerance ❙ Larger sizes and partial illumination allowed for larger EUT ❙ Smaller sizes allowed for smaller EUT (including cabling) ❙ Located 0.8 m above floor ❙ Distance from antenna tip: minimum 1 m, preferred 3 m

Uniform area criteria versus beamwidths and distance

Beamwidth: Θ = 2tan–1 [ ]W–––2DW

–––2D

Distance: D =W

–––––––2tan(Θ/2)

Window: W = 2Dtan [ ]Θ––2

28° 41° 74°

3 m 1 m2 m

Amplifier harmonics versus intercept point

Relationship between the power level of the fundamental and harmonic frequencies.

PFundamental ~ PGenerator

P2nd harmonics ~ (PGenerator)2

P3rd harmonics ~ (PGenerator)3

Remark:The saturation power of an amplifier can be much higher than the output power at P1 dB compression.

Fundamental signal output level in dBm

3rd order product3:1 Slope

Intercept diagram

+60

+40

+20

0

–20

–40

–60

–80

–100

–120

–140

–80 –60 –40 –20 0 20 40 60

dB

m

2nd order product2:1 slope

1:1 slope

2nd order intercept

3rd order intercept

Intercept signal level

Field strength % of nom. value

Nominal value 18 V/m

Fundamental 14 V/m 78 %

2nd harmonics 7.3 V/m 40 %

3rd harmonics 8.7 V/m 49 %

❙ Harmonics in the field must be below 6 dBc, filters are typically not required ❙ The formulas are only valid for the linear amplifier power range. In the nonlinear range, harmonics increase at a higher rate

EUT monitoring capabilitiesEUT monitoring capabilities

CANoe™CANalyzer™

Customersmonitoring PC

Video monitoringsystem

TTL I/Oconverter

Measurement orstimulus device

LAN (TCP/IP)

CAN, MOST, LIN, FlexRay™

Camera

Customer-specific

TTL

Physical parameters (U, l, f, T...)

EUT

CON (DCOM)

LAN (TCP/IP)

USB/LAN

LAN/GPIB/RS-232

R&S®EMC32-S

Signal processing Signal conversion Signal source

EMS radiated test setup

¸SMB100ARF and microwave signal generator

¸OSPopen switch and control platform

¸EMC32EMC measurement software

¸NRP-Zxxpower sensors

R&S®BBA150 broadband amplifier

R&S®HL046E log-perodic antenna

Formulass VSWRr Reflection coefficientaR Return loss

s

(VSWR)

V

V

max

min

r

V

V

←←→→

Prefl in % a dB

V

V

R in

lg 20←←→→

dB to ratio conversion table

1

1.005

1.010

1.015

1.020

1.025

1.030

1.035

1.040

1.045

1.050

1.055

1.060

1.065

1.070

1.075

1.080

1.085

1.090

1.095

60

50

40

35

34

33

32

31

30

29

28

27

aR

dB

0.002

0 ∞

0.005

0.045

0.024

0.022

0.012

0.015

0.010

0.027

0.020

0.017

0.007

0.029

0.041

0.038

0.036

0.031

0.034

0.043

s r 1.01 0.005 46.1 dB Amplitude ratio Power ratio

1.02 0.010 0.01 40.1 –100 dB 10–5 10–10

1.03 0.015 0.02 36.6 –50 dB 0.00316 0.00001

1.04 0.020 0.04 34.2 –40 dB 0.010 0.0001

1.05 0.024 0.06 32.3 –30 dB 0.032 0.001

1.06 0.029 0.08 30.7 –20 dB 0.100 0.010

1.07 0.034 0.11 29.4 –10 dB 0.316 0.100

1.08 0.038 0.15 28.3 –6 dB 0.501 0.251

1.09 0.043 0.19 27.3 –3 dB 0.708 0.501

1.10 0.048 0.23 26.4 –2 dB 0.794 0.631

1.11 0.052 0.27 25.6 –1 dB 0.891 0.794

1.12 0.057 0.32 24.9 0 dB 1.000 1.000

1.13 0.061 0.37 24.3 1 dB 1.122 1.259

1.14 0.065 0.43 23.7 2 dB 1.259 1.585

1.15 0.070 0.49 23.1 3 dB 1.413 2 ≈ 1.995

1.16 0.074 0.55 22.6 6 dB 2 ≈ 1.995 3.981

1.17 0.078 0.61 22.1 10 dB 3.162 10.000

1.18 0.083 0.68 21.7 20 dB 10.000 100.000

1.19 0.087 0.75 21.2 30 dB 31.623 1000.000

1.20 0.091 0.83 20.8 40 dB 100.000 10000.000

1.30 0.130 1.70 17.7 50 dB 316.228 100000.000

1.40 0.167 2.78 15.6 100 dB 105 1010

1.50 0.200 4.00 14.0

PP

Ratio dB

1

0

1010=RatioPPdB = ⋅

10 10

1

0

log

VV

Ratio dB

1

0

2010=RatioVVdB = ⋅

20 10

1

0

log

Wavelength – frequency conversion

300fm

MHz

λ

1.60 0.231 5.33 12.7

1.70 0.259 6.72 11.7

1.80 0.286 8.16 10.9

1.90 0.310 9.63 10.2

2.00 0.333 11.10 9.5

2.20 0.375 14.1 8.5

2.40 0.412 17.0 7.7

2.60 0.444 19.8 7.0

2.80 0.474 22.4 6.5

3.00 0.500 25.0 6.0

3.50 0.556 30.9 5.1

4.00 0.600 36.0 4.4

5.00 0.667 44.4 3.5

6.00 0.714 51.0 2.9

7.00 0.750 56.2 2.5

8.00 0.778 60.5 2.2

10.0 0.818 66.9 1.7

20.0 0.905 81.9 0.9

50.0 0.961 92.3 0.3

R

R

1 r s

1 r

0.05a10 1

s0.05a

10 1

+=

−

+=

−

−=

+

=R

s 1r

s 11

r 0.05 a

10

+ = −

=

R

R

s 1a 20 lg

s 1

1a 20 lg

r

RF fundamentals in commercial EMS testing

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Antennas for EMS applicationsAntenna type

Frequency range

Gain Permissible input power

Half-power beamwidth (E plane)

R&S®HL562E ultralog antenna

30 MHz to 6 GHz –8 dBi at 30 MHz8.5 dB at > 200 MHz

225 W CW at 30 MHz900 W CW at 80 MHz150 W CW at 6 GHz

80 ° to 30 °

R&S®HL223 log- periodic antenna

200 MHz to 1.3 GHz

≥ 6 dBi 1500 W CW at 200 MHz600 W CW at 1.3 GHz

approx. 60 °

R&S®HL046E log- periodic antenna

80 MHz to 3 GHz typ. 8.0 dBi 2100 W CW at 80 MHz900 W CW at 500 MHz375 W CW at 3 GHz

approx. 60 °

R&S®HL050E log- periodic antenna

750 MHz to 6 GHz typ. 8.5 dBi 100 W CW approx. 60 °

R&S®HF907 double-ridged horn antenna

800 MHz to 18 GHz 5 dBi to 14 dBi 300 W CW at 800 MHz150 W CW at 18 GHz

100 ° to 40 °

RF_fundamentals_po_en.indd 1 03.03.2015 11:51:09

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Trade names are trademarks of the owners

PD 3607.1713.82 | Version 01.00 | March 2015 (as)

Data without tolerance limits is not binding | Subject to change

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3607.1713.82 01.00 PD

P 1 en

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RF fundamentals in commercial EMS testing

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