Waveguide Bandpass Filters
 ALLEN
AVIONICS ROUND POST-IRIS COUPLED Waveguide Filters are available over
the 1.12 to 26.50 GHz frequency band.(WR-650 to WR-42) In the CPWB
Series Bandwidths may be as small as 0.3% to as large as 7% of the
center frequency. These filters are available with 4 to 12 "high Q"
resonant sections. Allen Avionics Waveguide Filters are normally
constructed using rectangular Brass Waveguide but Copper, Aluminum and
Invar are also available. All Waveguide filters are available with
additional options like cover flanges, choke flanges or with coaxial
transitions to SMA and other connectors. |
| Available
Frequency |
1.12 GHz –
26.5 GHz |
| Available
Bandwidth |
0.3% Up to
7% |
| Insertion
Loss |
(Depends on
the number of sections and BW) |
| Stop Band
Attenuation |
see graphs |
| Number of
Resonator Sections Available |
4 to 12 |
| VSWR |
1.50:1 |
| Standard
W/G Sizes |
WR650 to
WR42 |
| Dimensions |
See
drawings below.
Consult Factory for exact dimensions. |
|
|
CONNECTOR CODE CHART |
|
FEMALE ("N") |
FN |
|
MALE ("N") |
MN |
|
FEMALE SMA
|
FS |
|
MALE SMA |
MS |
|
2.4 mm FEMALE |
24F |
|
2.4 mm MALE |
24M |
|
CPR FLANGE |
CPR |
|
CPRG FLANGE |
CPRG |
|
CMR FLANGE |
CMR |
|
COVER FLANGE |
CF |
|
CHOKE FLANGE |
CH |
|
|
The curve to the left displays the Relative
Attenuation as a function of the Normalized 3dB Bandwidth for
medium bandwidth filters.(3.0%) The graphs supplied are designed
to give an approximation of the frequency response for the CPWB
series of Waveguide filters. Using these curves and a few simple
formulas shown below you can predict the attenuation for a given
number of sections. Curves for narrow bandwidths (0.3%) and wide
bandwidths (7.0%) are also provided. There are many variables
that affect the Frequency Response, Attenuation and Insertion
loss of Waveguide filters so when exact information is required
contact the factory at (516) 248-8080 or send email to
sales@allenavionics.com
|
|
The Frequency response curves we supply show the approximate attenuation
as a function of the normalized 3dB bandwidth. Using these graphs we can
calculate attenuation at a given frequency for a specified number of
sections or determine the number of sections required to meet a set of
given attenuation points.
EXAMPLE #1 (Find required # of sections) We
want a Bandpass filter centered at 10.0 GHz (FO) with a 3dB bandwidth of
100 MHz (FC). We have a stopband requirement of 60dB at 9.80GHz and
10.30GHz. First we need to determine the percentage bandwidth (%BW)
using the following formula to find the correct graph to use.
With a 1% bandwidth the graph for .3% above would give
us the best approximation. Now we have to look at the two stopband
requirements. The low side 60db attenuation point is 9.70GHz and the
high side is at 10.30GHz. Now we need to calculate the number of 3dB
bandwidths using the following formula.
Checking the above graph we can see that 8 sections will
have well over 60dB attenuation at both stopband requirements. |
EXAMPLE #2 (Find minimum attenuation at specified frequencies)
We want a Bandpass filter centered at 2.50 GHz (FO) with
a 3dB bandwidth of 10 MHz (FC) and we are thinking about using 6
sections. We need to find the minimum attenuation at 2.460GHz and
2.540GHz for 6 sections.
Using the same formula above we first find the %Bw to
determine the correct graph to use. In this problem the the %BW equals
0.4% so we can use the 0.3%bw graph again. Then from the second formula
we used in the first example we find that we have four (4) 3dB
bandwidths on each side.
Checking the above graph we can see with 6 sections we
will have greater than 50dB attenuation at both 2.460GHz and 2.540GHz
for a filter with 10MHz 3dB bandwidth.
Three plots are provided, 0.3%, 3.0% and 7.0% so the
approximate response can be determined for any bandwidth in the
range of .0.3% to 7.0% 
Checking the above graph we can see that 6 sections will
have well over 60dB attenuation at both stopband requirements. |
Allen Avionics has advanced simulation and modeling software that our
experienced Microwave engineers use in the design and manufacturing of
Circular Post Coupled Wave Guide Bandpass Filters.
This software combined with our Numerical Control
Machining Center gives us rapid design and production capabilities.
Allen Avionics has the ability to manufacture prototypes and short runs
quickly and reduce lead times on large production runs.
Our Microwave and Mechanical engineers are always
available to help with custom designs or applications. The sales force
at Allen Avionics is ready to help with information and prices. They try
to answer all quotes in 48 hours or less and are familiar with all our
microwave products. All our Microwave products are manufactured in the
USA using only American made material. |
| WR |
U.S. Mil.
__ /U |
FL— FU
GHz |
Inside
Width (a)
(in) |
|
WR650 |
RG69
(b)
RG103 (a) |
1.12-1.70 |
6.500 |
|
WR510 |
|
1.45-2.20 |
5.100 |
|
WR430 |
RG104 (b)
RG105 (a) |
1.70-2.60 |
4.300 |
|
WR340 |
RG112
(b)
RG113 (a) |
2.20-3.30 |
3.400 |
|
WR284 |
RG48
(b)
RG75 (a) |
2.60-3.95 |
2.840 |
|
WR229 |
RG340 (c)
RG341 (a) |
3.30-4.90 |
2.290 |
|
WR187 |
RG49 (b)
RG95
(a) |
3.95-5.85 |
1.872 |
|
WR159 |
RG343 (c)
RG344
(a) |
4.90-7.05 |
1.590 |
|
WR137 |
RG50
(b)
RG106 (a) |
5.850-8.200 |
1.372 |
|
WR112 |
RG51
(b)
RG68 (a) |
7.050-10.000 |
1.122 |
| WR90 |
RG52
(b)
RG67 (a) |
8.20-12.40 |
0.900 |
| WR75
|
RG346 (c)
RG347 (a) |
10.0-15.0 |
0.750 |
| WR62
|
RG91 (b)
RG349 (a) |
12.40-18.00 |
0.622 |
| WR51 |
RG352 (c)
RG351 (a) |
15.00-22.00 |
0.510 |
| WR42 |
RG53
(b)
RG121 (a) |
18.00-26.5
|
0.420 |
|
MODEL DESIGNATION
| Code |
Description |
| 1 |
Series |
| 2 |
Number of Sections |
| 3 |
Center Frequency (GHz) |
| 4 |
3 dB Bandwidth (MHz) |
| 5 |
Connector Code(Input/Output)
(see chart) |
| 6 |
WR Waveguide number |
|
| 1 |
2 |
3 |
4 |
5 |
6 |
| CPWB/ |
5/ |
20.25/ |
101.25/ |
CPR/CPR/ |
42 |
COMPLETE Part Number=
CPWB / 5 /20.25/ 101.25 / CPR / CPR / 42
Contact Factory With Your Specific Needs
For:
-Electrical Performance
-Mechanical Configuration
-Insertion Loss
|
MATERIAL
When bandwidths exceed the 7.0% limit for this
filter type or when insertion loss, length rejection required or
some other parameter cannot be met, Allen Avionics has many
other Filter constructions available which could be used to
solve the problem. Contact our sales department for assistance.
(516) 248-8080 or
sales@allenavionics.com |
|
|
The number of sections and the Waveguide size are the
basic parameters that determine the overall length of Round Post-Iris
coupled Microwave Filters.
Using some basic formulas and the wave guide width from
the table above you can calculate the approximate length for a given
Waveguide and number of sections.
From
EXAMPLE #1. We had a Bandpass filter
centered at 10 GHz with 1.0% BW. From the table above we see WR90 is the
best wave guide size for 10GHz. From the same table we see the width of
WR90 is 0.90 inches. Our previous calculations done for example #1
Indicated that we needed 8 sections to meet the required attenuation.
With the number of sections, % BW and Waveguide width we now we have all
the information we need to calculate the approximate length.
 N
= number of sections.
a = width of Waveguide in inches
L = Approximate length in inches
For bandwidths 0.3 to 3.0%
L = For 4-8 sections. L= (0.75 x N +
1) a
L = For 9-12 sections. L= (N + 1.0) a
For bandwidths > 3.0% to 7%
L = For 4-8 sections. L= (0.75 x N + 0.667) a
L = For 9-12 sections. L= (0.80 x N + 1.0) a
So for example #1 we have L= (0.75 x 8 + 1) .9 = 6.3 inches
ALLEN AVIONICS INC manufactures many
other types of microwave Filters. Our engineers will help you pick the
right filter to meet all the requirements you have for performance, size
and cost.
 Our
advanced simulation and modeling software will design and do
optimization of Circular Post Coupled filters, Metal-Insert Filters,
Iris Coupled Filters, Combline and Interdigital Filters All of our
Filters can be custom designed for your application and we offer fast
prototypes. No need to wait five or six weeks to test your idea or check
your system.
Allen Avionics Inc. started in 1960 And has 49 years
experience in design, Production, quality and they use it on every
product they make. Check out this Allen Avionics web site for all their
products. |
