http://www.mwireless.com/Noise_Source/Microwave_Broadband.pdf
B
ROADBAND
C
OAXIAL
M
ICROWAVE
N
OISE
S
OURCES
1 MH
Z TO
26.5 GH
Z
D
ESCRIPTION
Micronetics' line of broadband coaxial noise
sources are specially designed for easy
integration into microwave systems. They
are designed to be rugged with excellent
long-term stability.
R
UGGED
/S
TABLE
D
ESIGN
:
M
EDIUM
ENR B
ROADBAND
C
OAXIAL
M
ICROWAVE
N
OISE
S
OURCES
MODEL
FREQUENCY
RANGE
R F OUTPUT
ENR dB
STYLE
CODE
The heart of Micronetics microwave noise
source is a small chip and wire hermetic
noise module. This is embedded in the
housing with a precision launch to the
coaxial jack. This design is much more
stable and rugged than traditional coaxial
noise sources which rely on pill packaged
diodes and beryllium copper bellow assem-
blies which not only are less reliable, but
use hazardous materials.
NSL2
NST04*
NST18*
NST26*
1 MHz to 1000 MHz
10 MHz to 4 GHz
10 MHz to 18 GHz
100 MHz to 26.5 GHz
30 +/-1
25 (min)
25 (min)
24 (min)
N, N1
Y
Y
Y
L
OW
ENR B
ROADBAND
C
OAXIAL
M
ICROWAVE
N
OISE
S
OURCES
Micronetics low ENR noise sources feature a large value embedded attenuator
ideal for Y-factor tests. The attenuator serves dual purposes of lowering the ENR to
a suitable Y-factor amplitude and also improves both on and off state VSWR which
increases noise figure measurement accuracy.
MODEL
FREQUENCY
RANGE
ENR
VSWR
STYLE
CODE
T
EMP
/V
OLTAGE
S
TABILITY
:
The NST series noise sources all feature
an embedded regulated driver which offers
maximum stability of the noise diode RF
circuit.
NSL2L
NST04L*
NST18L*
NST26L*
1 MHz to 1000 MHz
10 MHz to 4 GHz
10 MHz to 18 GHz **
100 MHz to 26.5 GHz
14 - 16 dB
14 - 16 dB
13 - 17 dB
13 - 17 dB
1.3:1 (max)
1.3:1 (max )
1.4:1 (max)
1.6:1 (max)
N, N1
Y
Y
Y
S
PECIFICATIONS
s
Operating Temp: -55 to +95
o
C
s
Storage Temp: -65 to +125
o
C
s
Supply Voltage: +15 VDC, +28 VDC
s
Temperature Stability: 0.01 dB/
o
C
s
Ouput Impedance: 50 ohm
s
Peak Factor: 5:1
* TTL compatible
** 2 GHz to 18 GHz ENR range is 14-16 dB
T
AILORED
ENR F
OR
Y
OUR
N
OISE
F
IGURE
M
EASUREMENT
A
PPLICATION
Micronetics offers other ENR values upon request. The optimum ENR of the noise source is dependant on the expected noise
figure of the DUT. If the expected noise figure is high, the measured difference of the off and on noise source states will be too
hard to discern accurately with the DUT's comparatively large amount of self generated thermal noise. However if the expected
noise figure is very low than using a noise source with too high a level of ENR will cause the two measured values to have such
disparate amplitudes that non-linear dynamic range issues may compromise accuracy. Depending on how crucial the measure-
ment uncertainty window needs to be, the designer can mathematically calculate the theoretical best ENR. This process can be
exhaustive mathematically.
Table 1
indicates a quick rule of thumb for ENR vs. expected noise figure. It should be noted that
any path loss between the noise source and DUT must be accounted for. If a 10 dB noise source makes sense for the DUT but
there is a 10 dB coupler and 3 dB of insertion loss, than a noise source with a 20 - 25 dB ENR is needed.
Expected Noise Figure
0 to 10 dB
10 to 20 dB
20 to 35 dB
Noise Source Nominal ENR
5 dB
10 dB
15 dB
WEB: WWW.MICRONETICS.COM
MICRONETICS / 26 HAMPSHIRE DRIVE / HUDSON, NH 03051 / TEL: 603-883-2900 / FAX: 603-882-8987
http://www.mwireless.com/Noise_Source/Microwave_Broadband.pdf
B
ROADBAND
C
OAXIAL
M
ICROWAVE
N
OISE
S
OURCES
C
ALIBRATION
AND
Q
U A L I T Y
A
SSURANCE
:
H
OW
T
O
O
RDER
:
Each noise source is accurately calibrated using a reference noise source
traceable to NIST/NPL Calibration data consists of calibration points at 1 GHz intervals
across the fullband*. Data is supplied as a print out. Special calibration data can also be
supplied upon request (consult factory).
Standard choices are:
• More calibration points across the spectrum
• Special discrete calibration frequencies
• Data supplied in soft format as screen capture or text file on
floppy or CD-ROM
In addition to the calibration data, a certificate of calibration and a certificate of
conformance is supplied with each unit.
* 100 MHz intervals for the NSL-2
N S XXXX- X
Model
Bias Voltage
A = +28V
B = +15V
U
SING
N
OISE
F
OR
B
UILT
-I
N
-T
EST
:
There are three primary uses for employing a noise signal for built-in-test.
1. Noise Temperature (noise figure) or Sensitivity Testing:
This test uses the
noise source to supply a known excess noise ratio (ENR) to a device under test for a
Y-factor measurement. By taking two receiver readings, one with the noise on and one
with it off, Y-factor can be determined. By knowing the ENR and Y-factor, one can
calculate noise temperature (figure) or sensitivity.
2. Frequency Response:
The noise source being broadband can be used as a
replacement of a swept source to calculate frequency response of a receiver or other
device. By putting in a known spectral signal at the input and taking a reading at the
output, one can determine the gain or loss over frequency of the entire system. Noise
sources are inherently extremely stable devices. In addition, the circuitry is much simpler
than a swept source which increases reliability and lowers cost.
3. Amplitude Reference Source:
The noise source can be used as a known refer-
ence signal. By switching in the noise source from the live signal, a quick test can be
performed to check the health of the chain or calibrate the gain/loss. For this test, noise
can be injected into the IF system to test/calibrate its chain as well as the RF.
For more information on using noise for built-in-test, read the Feb 2004 Microwave
Journal article authored by Patrick Robbins of Micronetics.
http://www.micronetics.com/articles/microwave_journal_02-04.pdf
U
SEFUL
N
OISE
E
QUATIONS
Calculating Y-Factor:
Y
Fact
= N
2
/ N
1
Where N
2
is measured power output with noise
source on and N
1
is the measured power output with noise source off.
Calculating Noise figure from ENR and Y-factor:
NF(dB) = ENR (dB) - 10 log10 (Y
Fact
-1)
Converting ENR to Noise spectral density (N
0
):
0 dB ENR = -174 dBm/Hz
Calculating noise power in a given bandwidth (BW) from noise spectral density:
Power (dBm) = N
0
+ 10log(BW)
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