YOU'RE HEARD, LOUD AND CLEAR.
Instruction Manual
Vari-Notch
6 5/8” and 10” Diameter
Manual Part Number
®
Cavity Filter
7-9144
8625 Industrial Parkway, Angola, NY 14006 Tel: 716-549-4700 Fax: 716-549-4772 sales@birdrf.com www.bird-technologies.com
Warranty
This warranty applies for one year from shipping date.
TX RX Systems Inc. warrants its products to be free from defect in material and workmanship at the time of shipment.
Our obligation under warranty is limited to replacement or repair, at our option, of any such products that shall have
been defective at the time of manufacture. TX RX Systems Inc. reserves the right to replace with merchandise of
equal performance although not identical in every way to that originally sold. TX RX Systems Inc. is not liable for dam-
age caused by lightning or other natural disasters. No product will be accepted for repair or replacement without our
prior written approval. The purchaser must prepay all shipping charges on returned products. TX RX Systems Inc.
shall in no event be liable for consequential damages, installation costs or expense of any nature resulting from the
purchase or use of products, whether or not they are used in accordance with instructions. This warranty is in lieu of all
other warranties, either expressed or implied, including any implied warranty or merchantability of fitness. No representative is authorized to assume for TX RX Systems Inc. any other liability or warranty than set forth above in connection with our products or services.
TERMS AND CONDITIONS OF SALE
PRICES AND TERMS:
Prices are FOB seller’s plant in Angola, NY domestic packaging only, and are subject to change without notice. Federal, State and local sales or excise taxes are not included in prices. When Net 30 terms are applicable, payment is
due within 30 days of invoice date. All orders are subject to a $100.00 net minimum.
QUOTATIONS:
Only written quotations are valid.
ACCEPTANCE OF ORDERS:
Acceptance of orders is valid only when so acknowledged in writing by the seller.
SHIPPING:
Unless otherwise agreed at the time the order is placed, seller reserves the right to make partial shipments for which
payment shall be made in accordance with seller’s stated terms. Shipments are made with transportation charges collect unless otherwise specified by the buyer. Seller’s best judgement will be used in routing, except that buyer’s routing
is used where practicable. The seller is not responsible for selection of most economical or timeliest routing.
CLAIMS:
All claims for damage or loss in transit must be made promptly by the buyer against the carrier. All claims for shortages
must be made within 30 days after date of shipment of material from the seller’s plant.
SPECIFICATION CHANGES OR MODIFICATIONS:
All designs and specifications of seller’s products are subject to change without notice provided the changes or modifications do not affect performance.
RETURN MATERIAL:
Product or material may be returned for credit only after written authorization from the seller, as to which seller shall
have sole discretion. In the event of such authorization, credit given shall not exceed 80 percent of the original purchase. In no case will Seller authorize return of material more than 90 days after shipment from Seller’s plant. Credit
for returned material is issued by the Seller only to the original purchaser.
ORDER CANCELLATION OR ALTERATION:
Cancellation or alteration of acknowledged orders by the buyer will be accepted only on terms that protect the seller
against loss.
NON WARRANTY REPAIRS AND RETURN WORK:
Consult seller’s plant for pricing. Buyer must prepay all transportation charges to seller’s plant. Standard shipping policy set forth above shall apply with respect to return shipment from TX RX Systems Inc. to buyer.
DISCLAIMER
Product part numbering in photographs and drawings is accurate at time of printing. Part number labels on TX RX
products supersede part numbers given within this manual. Information is subject to change without notice.
Bird Technologies Group TX RX Systems Inc.
Manual Part Number 7-9144
Copyright © 1996 TX RX Systems, Inc.
First Printing: July 1996
Version Number Version Date
1 07/22/96
Symbols Commonly Used
WARNING
CAUTION or ATTENTION
High Voltage
Use Safety Glasses
ESD Elecrostatic Discharge
Hot Surface
Electrical Shock Hazard
NOTE
Important Information
Bird Technologies Group TX RX Systems Inc.
dBm
10
200
KHZ/DIV
98.00
MHZ
300
KHZ/RES
-10
-20
-30
-40
-50
-60
-70
0
40 dB ATT
INSERTION LOSS
REJECTION
NOTCH
GEN 0 dBM
Figure 1: Spectrum Analyzer / Tracking Generator display of the highpass Vari-Notch filter.
Response curve shown for model # 15-29-01 (88 - 108 MHz)
GENERAL DESCRIPTION
The Vari-Notch® cavity filter is designed to pass a
relatively narrow band of frequencies
(passband)
while simultaneously rejecting a wide band of frequencies
(rejection notch).
A variety of models
are available that cover the range of frequencies
from 30 to 960 MHz. The portion of the frequency
range that each model will tune across is determined by the cavity's physical length.
Either 6-5/8" or 10" diameter resonator shells may
be used to construct the filters. The difference between the two sizes determines the filters selectivity and it's maximum power dissipation. The 10"
diameter filters have a slightly higher selectivity
compared to the 6-5/8" models. Additionally, the
10" filters can safely dissipate up to 40 Watts of RF
Power, while the 6-5/8" filters can dissipate up to
30 Watts. Maximum input power for the 6" and 10"
diameter filter's is listed in table 1.
Insertion loss 6" diameter
power rating
10" diameter
power rating
0.3 dB 449 Watts 599 Watts
0.6 dB 230 Watts 308 Watts
Table 1: Input power ratings
PASSBAND
10 MSEC
Two types of Vari-Notch filters are available, lowpass and highpass. Lowpass filters have the passband below the notch frequency while highpass
filters have the passband above the notch.
The difference between the two types at VHF frequencies is determined by the inductive element
used in the construction of the loop plate assembly.
At UHF frequencies the same loop plate is used for
both low and highpass. The cavity itself remains
identical for both types. Figure 1 shows the re-
sponse curve of a highpass filter.
There are three adjustable parameters in a Vari-
Notch filter including the passband frequency, the
rejection notch frequency, and insertion loss.
Each of these parameters is labeled on the response curve shown in figure 1.
All of the physical components of the filter are labeled in figure 2, with the adjustable parts shown in
emboldened italics. Coarse and fine tuning rods
are used to adjust the passband while a variable
capacitor is used to adjust the rejection notch. The
insertion loss is adjusted by rotating the loop plate
assembly.
TX RX Systems Inc. Manual 7-9144-1 07/22/96 Page 1
Coarse Tuni ng Rod
Coarse Tuning Lock
10-32 Cap Screw
Loop Plate
Hole Cover
Cavity Resonator
Input / Output
Ports
Loop Plate
Assembly
Loop Plate
Hold Down Screws
Figure 2: The Vari-Notch filter.
Fine Tuning Rod
Fine Tuning Lock
Knurled Thumb Nut
Calibration Index
Calibration
Mark
Variable Capacitor
Access Barrel
TUNING
Required Equipment
The following equipment or it's equivalent is recommended in order to properly perform the tuning
adjustments for the Vari-Notch filter.
1. IFR A-7550 Spectrum Analyzer with optional
Tracking Generator installed.
2. Eagle Return Loss Bridge (model RLB150N3A).
3. Double shielded coaxial cable test leads
(RG142 B/U or RG223/U).
4. 50 Ohm load, with at least -35 dB return loss
(1.10:1 VSWR).
5. Connector - female union (UG 29-N or UG
914-BNC).
6. Insulated tuning tool (TX RX Systems Inc. part#
95-00-01).
7. 5/32" hex wrench.
Tuning Procedure
Tuning of the filter requires adjustment of the
band
and the
justed while observing the return loss response and
the rejection notch is adjusted by monitoring the
output of a tracking generator after it passes
through the filter. To insure proper tuning of the
Vari-Notch filter, all adjustments should be performed in the following order:
1. Rough tune the passband.
2. Rough tune the rejection notch.
3. Final tune the passband.
4. Final tune the rejection notch, always the last
adjustment made.
The peak of the passband will correspond very
closely to the point of minimum reflected energy
from the filter and maximum forward power through
it. A transmitter connected to the filter will
rejection notch
PASSBAND
. The passband is ad-
pass-
operate
TX RX Systems Inc. Manual 7-9144-1 07/22/96 Page 2
best when the reflected energy is lowest, therefore
the return loss response will be used to set the
passband. The passband can be checked and adjusted using the following procedure.
Checking the passband
1. A zero reference for return loss must be established at the IFR A-7550 prior to checking the
passband frequency, this is done by connecting
the return loss bridge to the analyzer / generator as shown in figure 3.
200
dBm
KHZ / DIV
40
30
20
10
0
-10
-20
-30
-40
dB
40
ANALYZER
98.00
MHZ
ATT
GEN
dBM
0
300
KHZ RES
MSEC
10
GENERATE
4. Insure that the IFR A-7550 menu's are set as
follows: DISPLAY - line
MODE - live
FILTER - none
SETUP - 50 ohm/dBm/gen1.
5. The flat line across the screen is the return loss
curve. Select the "Mode" main menu item and
then choose the "Store " command.
6 Next select the "Display" main menu item and
choose the "Reference" command. This will
cause the stored value
to be displayed at the
center of the screen as the 0 dB reference
value.
7. Connect the "load" port on the RLB to the input
of the loop plate, make sure the output of the
loop plate is connected to a 50 ohm load, refer
to figure 4. The display will now present the return loss curve for the Vari-Notch filter being
measured. The passband is that frequency
range over which the return loss is 15 dB or
greater.
Adjusting the passband
Set the fine tuning knob at it's mid-point. Adjust the
passband by setting the peak (maximum negative
value) of the return loss curve at the desired passband frequency (should be the center-vertical
graticule line on the IFR A-7550's display). Refer to
figure 4.
RLB - 150 BRIDGE
REFLECTED
SOURCE
LOAD
Figure 3: Setting the return loss reference.
2. Set-up the analyzer / generator for the desired
frequency (center of display) and for a vertical
scale of 10 dB/div.
3. Do not connect the return loss bridge to the
cavity, leave the "load" port on the bridge open.
This will supply the maximum amount of reflected energy to the analyzer input.
TX RX Systems Inc. Manual 7-9144-1 07/22/96 Page 3
The resonant frequency is adjusted by using the
coarse tuning rod, which is a sliding adjustment (invar rod) that rapidly tunes the response curve
across the frequency range of the filter. Resonant
frequency is increased by pulling the rod out of the
cavity and is decreased by pushing the rod into the
cavity. Additionally, the fine tuning rod, also a sliding adjustment (silver-plated-brass rod ), allows a
more precise setting of the frequency after the
coarse adjustment is made. The frequency is increased by pushing the fine tuning rod in and is decreased by pulling it out; the exact opposite of the
coarse tuning rod.
Once the desired response is obtained using the
coarse and fine tuning rods, they are "locked" in
place. The coarse rod is secured by tightening the
10-32 cap screw and the fine tuning rod is held in
place by tightening the knurled thumb nut. Failure
to lock the tuning rods will cause a loss of
200
dBm
KHZ / DIV
40
30
20
10
0
-10
-20
-30
-40
dB
40
ANALYZER
pressure weld that maintains excellent conductivity.
98.00
MHZ
300
KHZ RES
The pressure weld develops over time and must be
broken in order for the main tuning rod to move.
This is easily accomplished by gently tapping the
tuning rod with a plastic screwdriver handle or
small hammer so it moves into the cavity. The
pressure weld will be broken with no damage to the
cavity.
REJECTION NOTCH
The rejection notch will track with the tuning of the
passband and therefore should be the last adjustment made to the Vari-Notch filter. The rejection
notch is adjusted by changing the amount of ca-
ATT
GEN
dBM
0
MSEC
10
GENERATE
pacitance in the loop plate assembly. The capacitor
is variable and is either an air-plate or a tubularpiston type depending upon the frequency range of
the filter.
On UHF models (400 MHz and over) the capacitor
access barrel is omitted and a 10-32 screw must
RLB - 150 BRIDGE
REFLECTED
then be removed from the loop plate assembly to
gain access to the piston trimmer under the plate.
The air-plate type has a red mark painted on the
SOURCE
LOAD
access barrel and one-half of the adjusting screw,
when the red marks line up the maximum capacitance is achieved.
VARI-NOTCH
FILTER
20
15
10
5
0
50 OHM LOAD
Figure 4: Checking the passband.
temperature compensation and detuning of the
cavity.
Cavity Tuning Tip
When tuning a cavity that has been in service for
some time it is not unusual to find the main tuning
rod hard to move in or out. This occurs because
TX RX Systems Inc. uses construction techniques
borrowed from microwave technology that provide
large area contact surfaces on our tuning probes.
These silver plated surfaces actually form a
Checking the rejection notch
1. The rejection notch is checked by connecting
the tracking generator to the input of the cavity
filter while the spectrum analyzer is connected
to the output, as illustrated in figure 5.
2. Insure that the IFR A-7550 menu's are set as
follows: DISPLAY - line
MODE - live
FILTER - none
SETUP - 50 ohm/dBm/gen1.
Adjusting the rejection notch
The notch is adjusted by turning the variable capacitor. Because of the filters sensitivity to tool
contact, an insulated tuning tool must be used to
make the adjustment.
INSERTION LOSS
Insertion loss is not usually adjusted when retuning the Vari-Notch filter in the field. Insertion
loss is factory set, at which time a relative index
label is attached to the top of the cavity next to the
loop plate and a calibration mark is stamped into
the loop plate itself. The calibration mark is normally aligned so that the index value of 15 will be
TX RX Systems Inc. Manual 7-9144-1 07/22/96 Page 4
dBm
-10
-20
-30
-40
dB
200
KHZ / DIV
10
0
97.00
MHZ
300
KHZ RES
200
KHZ / DIV
8
6
4
2
0
-2
98.00 300
MHZ
KHZ RES
-50
-60
-70
dB
40
ANALYZER
ATT
VARI-NOTCH
FILTER
-4
-6
-8
dB
ATT
GEN
dBM
0
MSEC
10
GENERATE
40
ANALYZER
Used to determine 0 dB reference
VARI-NOTCH
FILTER
20
15
10
5
0
GEN
dBM
0
FEMALE UNION
20
15
10
5
0
MSEC
10
GENERATE
Figure 5: Checking the rejection notch.
equal to an insertion loss of 0.6 dB. The relative
index label is used to log specific filter performance.
. The insertion loss setting determines the re-
jection response of the cavity and a change will
cause a shift in both the passband and rejection
notch. Higher insertion loss settings will allow
closer passband to notch frequency separations.
Insertion loss can be checked using the IFR
A-7550 spectrum analyzer by following the proce-
dure listed below.
Checking the insertion loss
1. A zero reference must first be established at the
IFR A-7550 before the insertion loss can be
measured. This is accomplished by temporarily
TX RX Systems Inc. Manual 7-9144-1 07/22/96 Page 5
Figure 6: Checking insertion loss.
placing a "female union" between the generator
output and analyzer input, see figure 6.
2. Setup the analyzer / generator for the desired
frequency and bandwidth (center of display) and
also a vertical scale of 2 dB/div.
3. Insure that the IFR A-7550 menu's are set as
follows: DISPLAY - line
MODE - live
FILTER - none
SETUP - 50 ohm/dBm/gen1.
4. The flat line across the screen is the generator's
output with no attenuation, this value will become our reference by selecting the "Mode"
main menu item and choosing the "Store"
command.
5. Next select the "Display" main menu item and
choose the "Reference" command. This will
cause the stored value
to be displayed at the
center of the screen as the 0 dB reference
value.
6. Connect the generator output and analyzer input to the input/output ports of the loop plate
and the amount of insertion loss offered by the
Vari-Notch filter will be displayed on the IFR
A-7550's screen, refer to figure 6.
Adjusting the insertion loss
Adjustments are made by loosening the three
10-32 screws that hold the loop plate into position
and then rotating the plate itself. When the calibration mark is pointed at the relative index setting of
15 the insertion loss will be 0.6 dB (calibrated by
factory).
Rotating the loop plate assembly and moving the
calibration mark above or below 15 causes the insertion loss to be increased or decreased (above
15 increases the loss while below 15 decreases it).
Insertion loss is adjustable across a useable range
of from 0.3 dB to 1.0 dB.
MULTIPLE CAVITY VARI-NOTCH FILTERS
Vari-Notch filters can be ordered in multiple cavity
arrangements of either two or three combined cavities. In these arrangements, identical filters are
connected in a cascaded fashion with the output of
each filter fed to the input port of the succeeding
filter. The advantage to this arrangement is that the
amount of attenuation provided by each of the filters is additive. In the case of the rejection notch
frequency, the dual cavity can provide attenuation
of over 60 dB (30 dB for each filter).
Also, the interconnecting cable between the two
filters, when cut to the correct length (odd multiple
of a 1/4 λ), will provide up to 6 dB of additional attenuation due to a mismatch of impedance between the cable and the filters. The 6 dB of
mismatch attenuation does not occur at the filters
passband but, only at frequencies where moderate
to high attenuation occurs, such as at the rejection
notch frequency. Because each of the filters in the
multi-cavity arrangement are identical, the passband for the entire arrangement is generally the
same as the passband for the individual filters.
However, each filters individual insertion loss is
also additive. When tuning a multi-cavity arrangement, each filter is tuned individually prior to interconnecting them. Then each is fine tuned to peak
the overall response of the multi-cavity
arrangement.
CONVERTING CAVITY RESONANT FILTERS
TX RX Systems Inc. produces four types of cavity
filters, including the Vari-Notch®, Series-Notch®,
Bandpass, and T-Pass®. The cavity resonator shell
along with the coarse and fine tuning controls are
standard subassemblies found in each type of filter
for a specified frequency band. Differences between the types are determined by the loop plate
assemblies installed in the filter.
The filter's loop plate assembly may be changed in
order to convert the cavity from one type of filter to
another. Conversion kits can be ordered which
contain all parts required for the conversion. The
available kits are listed by part number in table 2.
Refer to the appropriate TX RX Systems Inc. manual for the specific filter type once the kit is
installed.
Vari- Notch
Filter Part #
15-28-01/-11
15-28-05/-25
15-29-01/-11
15-29-05/-25
15-35-01/-11
15-35-05/-25
15-36-01/-11
15-36-05/-25
15-37-01/-11
15-37-05/-25
15-65-01/-11
15-65-05/-25
15-69-01/-11
15-69-05/-25
15-70-01/-11
15-70-05/-25
diameter and wavelength as listed below;
1.) Last digit of "01" indicates 6-5/8" diameter and 1/4 λ.
2.) Last digit of "11" indicates 6-5/8" diameter and 3/4 λ.
3.) Last digit of "05" indicates 10" diameter and 1/4 λ.
4.) Last digit of "25" indicates 10" diameter and 3/4 λ.
Series-Notch
( Lowpass )
Conversion
Kit Part #
76-28-04 76-28-05 76-28-01 76-28-07
76-29-04 76-29-05 76-29-01 76-29-07
76-35-04 76-35-05 76-35-01 76-35-07
76-36-05 76-36-06 76-36-01 76-38-01
76-37-05 76-37-06 76-37-01 76-38-01
76-65-04 76-65-05 76-65-01 76-67-01
76-69-04 76-69-05 76-69-01 76-67-01
76-70-04 76-70-05 76-70-01 76-67-01
Note: The last two digits of the filters model number indicate it's
Series-Notch
( Highpass )
Conversion
Kit Part #
Bandpass
Conversion
Kit Part #
T-Pass
Conversion
Kit Part #
Table 2: Conversion kit part numbers.
TX RX Systems Inc. Manual 7-9144-1 07/22/96 Page 6
Isolation Curves for Transmitter/Receiver
The curves shown below for use with filters, duplexers, and multicouplers, indicate the
amount of isolation or attenuation required between a typical 100 watt transmitter and its
associated receiver at the TX (carrier suppression) and RX (noise suppression) frequency
which will result in no more than a 1 dB degradation of the 12 dB SINAD sensitivity.
100
90
80
70
Attenuation
60
50
40
100
132 - 174 MHz Band
For TX Power of:
25 watts -
50 watts 100 watts 250 watts 350 watts -
.2 .3 .4 .5 .6 .7 .8 .9 1 2 3 4 5 6 7 8 9 10
subtract 6 dB
subtract 3 dB
no correction
add 4 dB
add 5.5 dB
400 - 512 MHz Band
Frequency Separation (MHz)
90
80
70
Attenuation
60
50
40
NOTE
For TX Power of:
25 watts -
50 watts 100 watts 250 watts 350 watts -
.2 .3 .4 .5 .6 .7 .8 .9 1 2 3 4 5 6 7 8 9 10
These are only "typical" curves. When accuracy is required, consult the radio manufacturer.
subtract 6 dB
subtract 3 dB
no correction
add 4 dB
add 5.5 dB
Frequency Separation (MHz)
Bird Technologies Group TX RX Systems Inc.
Power Ratio and Voltage Ratio to Decibel
Conversion Chart
Loss or Gain Power Ratio Voltage Ratio
+9.1 dB 8.128 2.851
-9.1 dB 0.123 0.351
- dB +- dB +
Voltage
Ratio
1 1 0 1 1
0.989 0.977 0.1 1.012 1.023
0.977 0.955 0.2 1.023 1.047
0.966 0.933 0.3 1.035 1.072
0.955 0.912 0.4 1.047 1.096
0.944 0.891 0.5 1.059 1.122
0.933 0.871 0.6 1.072 1.148
0.923 0.851 0.7 1.084 1.175
0.912 0.832 0.8 1.096 1.202
0.902 0.813 0.9 1.109 1.23
0.891 0.794 1 1.122 1.259
0.881 0.776 1.1 1.135 1.288
0.871 0.759 1.2 1.148 1.318
0.861 0.741 1.3 1.161 1.349
0.851 0.724 1.4 1.175 1.38
0.841 0.708 1.5 1.189 1.413
0.832 0.692 1.6 1.202 1.445
0.822 0.676 1.7 1.216 1.479
0.813 0.661 1.8 1.23 1.514
0.804 0.646 1.9 1.245 1.549
0.794 0.631 2 1.259 1.585
0.785 0.617 2.1 1.274 1.622
0.776 0.603 2.2 1.288 1.66
0.767 0.589 2.3 1.303 1.698
0.759 0.575 2.4 1.318 1.738
0.75 0.562 2.5 1.334 1.778
0.741 0.55 2.6 1.349 1.82
0.733 0.537 2.7 1.365 1.862
0.724 0.525 2.8 1.38 1.905
0.716 0.513 2.9 1.396 1.95
0.708 0.501 3 1.413 1.995
0.7 0.49 3.1 1.429 2.042
0.692 0.479 3.2 1.445 2.089
0.684 0.468 3.3 1.462 2.138
0.676 0.457 3.4 1.479 2.188
0.668 0.447 3.5 1.496 2.239
0.661 0.437 3.6 1.514 2.291
0.653 0.427 3.7 1.531 2.344
0.646 0.417 3.8 1.549 2.399
0.638 0.407 3.9 1.567 2.455
0.631 0.398 4 1.585 2.512
0.624 0.389 4.1 1.603 2.57
0.617 0.38 4.2 1.622 2.63
0.61 0.372 4.3 1.641 2.692
0.603 0.363 4.4 1.66 2.754
0.596 0.355 4.5 1.679 2.818
0.589 0.347 4.6 1.698 2.884
0.582 0.339 4.7 1.718 2.951
0.575 0.331 4.8 1.738 3.02
0.569 0.324 4.9 1.758 3.09
Power
Ratio
dB
Voltage
Ratio
Power
Ratio
Voltage
Ratio
0.562 0.316 5 1.778 3.162
0.556 0.309 5.1 1.799 3.236
0.55 0.302 5.2 1.82 3.311
0.543 0.295 5.3 1.841 3.388
0.537 0.288 5.4 1.862 3.467
0.531 0.282 5.5 1.884 3.548
0.525 0.275 5.6 1.905 3.631
0.519 0.269 5.7 1.928 3.715
0.513 0.263 5.8 1.95 3.802
0.507 0.257 5.9 1.972 3.89
0.501 0.251 6 1.995 3.981
0.496 0.246 6.1 2.018 4.074
0.49 0.24 6.2 2.042 4.169
0.484 0.234 6.3 2.065 4.266
0.479 0.229 6.4 2.089 4.365
0.473 0.224 6.5 2.113 4.467
0.468 0.219 6.6 2.138 4.571
0.462 0.214 6.7 2.163 4.677
0.457 0.209 6.8 2.188 4.786
0.452 0.204 6.9 2.213 4.898
0.447 0.2 7 2.239 5.012
0.442 0.195 7.1 2.265 5.129
0.437 0.191 7.2 2.291 5.248
0.432 0.186 7.3 2.317 5.37
0.427 0.182 7.4 2.344 5.495
0.422 0.178 7.5 2.371 5.623
0.417 0.174 7.6 2.399 5.754
0.412 0.17 7.7 2.427 5.888
0.407 0.166 7.8 2.455 6.026
0.403 0.162 7.9 2.483 6.166
0.398 0.159 8 2.512 6.31
0.394 0.155 8.1 2.541 6.457
0.389 0.151 8.2 2.57 6.607
0.385 0.148 8.3 2.6 6.761
0.38 0.145 8.4 2.63 6.918
0.376 0.141 8.5 2.661 7.079
0.372 0.138 8.6 2.692 7.244
0.367 0.135 8.7 2.723 7.413
0.363 0.132 8.8 2.754 7.586
0.359 0.129 8.9 2.786 7.762
0.355 0.126 9 2.818 7.943
0.351 0.123 9.1 2.851 8.128
0.347 0.12 9.2 2.884 8.318
0.343 0.118 9.3 2.917 8.511
0.339 0.115 9.4 2.951 8.71
0.335 0.112 9.5 2.985 8.913
0.331 0.11 9.6 3.02 9.12
0.327 0.107 9.7 3.055 9.333
0.324 0.105 9.8 3.09 9.55
0.32 0.102 9.9 3.126 9.772
Power
Ratio
dB
Voltage
Ratio
Power
Ratio
Bird Technologies Group TX RX Systems Inc.
POWER IN/OUT
VS
INSERTION LOSS
The graph below offers a convenient means of determining the insertion loss of filters, duplexers,
multicouplers and related products. The graph on the back page will allow you to quickly determine
VSWR. It should be remembered that the field accuracy of wattmeter readings is subject to
considerable variance due to RF connector VSWR and basic wattmeter accuracy, particularly at low
end scale readings. However, allowing for these variances, these graphs should prove to be a useful
reference.
INSERTION LOSS (dB)
500
400
300
250
200
150
125
INPUT POWER (Watts)
100
7.0
6.5
6.0
5.5
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
.50
.25
75
50
50
75 100
125 150 200
250
300
400
500
OUTPUT POWER (Watts)
FOR LOWER POWER LEVELS
DIVIDE BOTH SCALES
BY 10 (5 TO 50 WATTS)
Bird Technologies Group TX RX Systems Inc.
500
400
300
200
100
50
40
30
20
POWER FWD./REV.
VS
VSWR
V
S
W
R
1.1:1
1.15:1
1.2:1
10
FORWARD POWER (Watts)
5.0
4.0
3.0
2.0
1.0
0.5
40
20
10
8.0 6.0
4.0
2.0
REFLECTED POWER (Watts)
FOR OTHER POWER LEVELS
MULTIPLY BOTH SCALES
BY THE SAME MULTIPLIER
1.0 0.8
0.6
0.4
1.25:1
1.3:1
1.4:1
1.5:1
1.6:1
1.8:1
2.0:1
2.5:1
3.0:1
0.2
Bird Technologies Group TX RX Systems Inc.
Return Loss vs. VSWR
Watts to dBm
Return Loss VSWR
30 1.06
25 1.11
20 1.20
19 1.25
18 1.28
17 1.33
16 1.37
15 1.43
14 1.50
13 1.57
12 1.67
11 1.78
10 1.92
9 2.10
Watts dBm
300 54.8
250 54.0
200 53.0
150 51.8
100 50.0
75 48.8
50 47.0
25 44.0
20 43.0
15 41.8
10 40.0
5 37.0
4 36.0
3 34.8
2 33.0
1 30.0
dBm = 10log P/1mW
Where P = power (Watt)
Insertion Loss
Input Power (Watts)
50 75 100 125 150 200 250 300
3 25 38 50 63 75 100 125 150
2.5 28 42 56 70 84 112 141 169
2 32 47 63 79 95 126 158 189
1.5 35 53 71 88 106 142 177 212
1 40 60 79 99 119 159 199 238
Insertion Loss
.5 45 67 89 111 134 178 223 267
Output Power (Watts)
Free Space Loss
Distance (miles)
.25 .50 .75 1 2 5 10 15
150 68 74 78 80 86 94 100 104
220 71 77 81 83 89 97 103 107
460 78 84 87 90 96 104 110 113
860 83 89 93 95 101 109 115 119
940 84 90 94 96 102 110 116 120
Frequency (MHz)
1920 90 96 100 102 108 116 122 126
Free Space Loss (dB)
Free space loss = 36.6 + 20log D + 20log F
Where D = distance in miles and F = frequency in MHz
Bird Technologies Group TX RX Systems Inc.
8625 Industrial Parkway, Angola, NY 14006 Tel: 716-549-4700 Fax: 716-549-4772 sales@birdrf.com www.bird-technologies.com
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