Test with Confidence™
MI-231 Family of
Dual-Polarized Feeds
The MI-231 Family of Dual-Polarized Feeds are high precision broadband dual-ported,
dual-polarized feeds ideal for near-field and compact range testing.
• Aperture includes a choke flange that optimizes
the antenna radiation pattern
• Low back radiation from the feed (front to back
ratio better than 25 dB)
• Excellent antenna radiation pattern stability
across the frequency band to maintain optimum
illumination of a compact range reflector across
the full waveguide frequency bandwidth
• Standard Type N female connectors on both
feed ports (higher frequency models include
2.92 mm connectors)
• Integral mechanical mounting flanges that permit
the feeds to be mounted without pressure on the
feed body, thus eliminating possibility to deform
the feed
Description
Applications
Ten models are available in the MI-231 Family of DualPolarized Feeds, each is designed to operate over a
standard rectangular waveguide band and together they
cover the 1.1 to 40 GHz frequency range.
The MI-231 Family of Dual-Polarized Feeds is
designed for multiple applications including:
The MI-231 feeds combine a high performance
broadband orthomode transducer with precision circular
waveguide feeding a circularly symmetric waveguide
aperture. The two ports of an MI-231 feed excite two
orthogonal TE11 modes in the circular guide which
radiate orthogonal linearly-polarized fields with cross
polarization suppression better than 35 dB.
• Source antennas for high quality compact range
measurements
• Probes for near-field antenna measurement testing,
and specifically, for systems capable of supporting
multiplexed measurements
• Any application where a broadband orthomode feed
is required
Spherical near-field testing requires the acquisition of
large amounts of data on a sphere surrounding the test
antenna at a small range length. Two orthogonal linearlypolarized components of the E-field are measured.
With a single-mode probe, which responds to a single
linearly-polarized component of the E-field, two raster
scans are required to measure all the near-field data
necessary to compute the far-field of a test antenna.
The MI-231 Feeds, which respond to two orthogonal
linearly-polarized components of the E-field, can be
used to measure all the necessary data in a single scan,
reducing the data acquisition time required for spherical
near-field testing.
Specifications
Model
Frequency Range
(GHz)
Nominal VSWR
Band
Connector Type
Weight (lbs.)
MI-231-1.1
1.12 - 1.7
1.5 (max < 2)
L
N Female (2)
101
MI-231-1.7
1.7 - 2.6
1.5 (max < 2)
LS
N Female (2)
48
MI-231-2.6
2.6 - 3.95
1.5 (max < 2)
S
N Female (2)
23
MI-231-3.95
3.95 - 5.85
1.5 (max < 2)
C
N Female (2)
7.5
MI-231-5.85
5.85 - 8.2
1.5 (max < 2)
XN
N Female (2)
4.7
MI-231-8.2
8.2 - 12.4
1.5 (max < 2)
X
N Female (2)
2
MI-231-10
10 - 15
1.5 (max < 2)
X-Ku
N Female (2)
1.9
MI-231-12.4
12.4 - 18
1.5 (max < 2)
Ku
N Female (2)
1.7
MI-231-18
18 - 26.5
1.5 (max < 2)
K
2.92 mm Female (2)
0.6
MI-231-26
26.5 - 40
1.5 (max < 2.5)
Ka
2.92 mm Female (2)
0.3
General Characteristics
> 35 dB
Interport Isolation (Port-to-Port)
> 40 dB
Operating Temperature Range
10°C - 35°C
Interface Connector
Type N Female or K Connector (see table)
Gain (Nominal)
10 dBi ±0.5 dB
3 dB Beamwidth
57° ±4°
Max Power
25 Watts
Isolation (dB)
VSWR Side Port
VSWR Rear Port
Cross Polarization Discrimination
MI−231−8.2 VSWR and Isolation
2
1.75
1.5
1.25
1
8.2
2
8.6
9
9.4
9.8
10.2
10.6
11
11.4
11.8
12.2
8.6
9
9.4
9.8
10.2
10.6
11
11.4
11.8
12.2
8.6
9
9.4
9.8
10.2 10.6
Frequency (GHz)
11
11.4
11.8
12.2
1.75
1.5
1.25
1
8.2
−40
−50
−60
−70
−80
8.2
Optional hardware may be added to an MI-231 feed which supports mounting the feed into a MI Technologies compact range feed positioner. When ordering, add an “ASY”
to the end of the model number to designate the addition of the compact range mounting hardware. For example, “MI-231ASY-3.9” is used to order the MI-231-3.9 feed
assembled with a flange.
0
MI−231−8.2 Rear Port Radiation Pattern at 10.2 GHz
−5
−10
Nomalized Directivity (dB)
−15
−20
−25
−30
−35
−40
−45
−50
E−Plane Co−Pol
E−Plane X−Pol
H−Plane Co−Pol
H−Plane X−Pol
−55
−60
−90
0
−75
−60
−45
−30
−15
0
15
θ (deg)
30
45
60
75
90
MI−231−8.2 Side Port Radiation Pattern at 10.2 GHz
−5
−10
Nomalized Directivity (dB)
−15
−20
−25
−30
−35
−40
−45
−50
E−Plane Co−Pol
E−Plane X−Pol
H−Plane Co−Pol
H−Plane X−Pol
−55
−60
−90
−75
−60
−45
−30
−15
0
15
θ (deg)
30
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Information contained herein shall not be used as a contractual document.
All products and their specifications subject to change without notice.
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45
60
75
90
DS-231-1.0/08/14