YOU'RE HEARD, LOUD AND CLEAR.
Instruction Manual
®
Series-Notch
6 5/8” and 10” Diameter
Manual Part Number
Cavity Filters
7-9146
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 7-9146
Copyright © 1996 TX RX Systems, Inc.
First Printing: July 1996
Version Number Version Date
1 07/25/96
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.
GENERAL DESCRIPTION
The Series-Notch® cavity filter passes a relatively
wide band of frequencies (
passband
) while
simultaneously rejecting a very narrow band of
frequencies (
notch frequency
). Minimum
separation between passband and notch frequency
is 50 KHz. The notch depth is variable from 15 to
25 dB. A variety of models are available that cover
the range of frequencies from 30 to 960 MHz. 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 diameter
difference between the two determines the filters
selectivity and it's maximum power dissipation. The
10" diameter filters have a slightly higher selectivity
(more attenuation at the notch frequency)
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
There are three adjustable parameters found in a
Series-Notch filter including the passband
frequency, the notch frequency, and notch
depth. Each of these parameters is labeled on the
response curve shown in figure 1.
Two types of Series-Notch filters are available,
lowpass and highpass. Lowpass filters permit a
very narrow separation between the notch and the
low frequency portion of the passband. Likewise,
highpass filters will permit a very narrow separation
between the notch and the high frequency
passband. The lowpass filter, unlike the highpass
filter, can be tuned for a symmetrical response.
The difference between the two types of filters is
determined by the loop plate assembly used. The
cavity itself remains identical for both types. The
part number is stamped on the loop.
dBm
20
10
0
-10
-20
-30
-40
-50
-60
1
MHZ/DIV
50 dB ATT
Notch Frequency
98.00
MHZ
Passband
GEN 0 dBM
Notch Depth
300
KHZ/RES
10 MSEC
Figure 1:
Spectrum Analyzer / Tracking Generator display of
the Series-Notch filter tuned lowpass. Response
curve above is for model # 20-29-01 ( 88 - 108 MHz).
dB
40
30
20
10
0
-10
-20
-30
-40
1
MHZ/DIV
50 dB ATT
98.00
MHZ
Passband
GEN 0 dBM
Notch Frequency
300
KHZ/RES
10 MSEC
Figure 2:
Return loss response curve for the "lowpass"
Series-Notch filter shown in figure 1. Response curve
above is for model # 20-29-01 ( 88 - 108 MHz).
low frequency passband and the high frequency. A
symmetrical response can only be obtained with
relatively large separations between pass and
notch frequencies. Figure 4 shows the resulting
return loss curve.
Figure 1 shows the response curve of a lowpass
filter while figure 2 shows the same filter's return
loss curve. A symmetrical response can be seen
in figure 3 where the notch is centered between the
TX RX Systems Inc. Manual 7-9146-1 07/25/96 Page 1
All of the physical components of the filter are
labeled in figure 5, with the adjustable parts shown
in emboldened italics. Coarse and fine tuning rods
are used to adjust the notch (resonant) frequency.
dBm
20
10
1
MHZ/DIV
Low Frequency Portion
Passband
98.00
MHZ
Passband
High Frequency Portion
300
KHZ/RES
dB
40
30
1
MHZ/DIV
98.00
MHZ
300
KHZ/RES
0
-10
-20
-30
-40
-50
-60
50 dB ATT
Notch Frequency
GEN 0 dBM
Notch Depth
10 MSEC
Figure 3:
Spectrum Analyzer / Tracking Generator display of the
Series-Notch filter tuned symmetrically. Response
curve above is for model # 20-29-01 ( 88 - 108 MHz).
The passband is adjusted with a variable capacitor
and the notch depth is changed by rotating the loop
plate assembly. One of two input/output ports will
be marked with a red dot to indicate this particular
20
10
Low Frequency Portion
0
-10
-20
-30
-40
50 dB ATT
Passband
GEN 0 dBM
Notch Frequency
High Frequency Portion
Passband
10 MSEC
Figure 4:
Return loss response curve for the "symmetrical"
Series-Notch filter shown in figure 3. Response curve
above is for model # 20-29-01 ( 88 - 108 MHz).
port has the best VSWR characteristics. The
marked port should be used as the input port. In
multiple cavity systems, the non-red dot port is
connected to the next filter's marked port.
Coarse Tuning 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 5: The Series-Notch Filter
Fine Tuning Rod
Knurled Thumb Nut
Fine Tuning Lock
Calibration Index
Calibration Mark
Variable
Capacitor
Access Barrel
TX RX Systems Inc. Manual 7-9146-1 07/25/96 Page 2
TUNING
Required Equipment
The following equipment or it's equivalent is
recommended in order to properly perform the
tuning adjustments for the Series-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
frequency
Adjustment of the
and the
notch depth
passband frequency
is optional because
notch
it is usually factory set in most cases. The
passband frequency is adjusted using a return loss
curve which is generated using a tracking
generator and return loss bridge. The notch
frequency and notch depth are adjusted by
monitoring the output of a tracking generator after
it passes through the filter. To insure proper tuning
of the Series-Notch filter, all adjustments should be
performed in the following order:
1. Adjust the notch depth (optional).
2. Rough tune the notch frequency.
3. Rough tune the passband frequency.
4. Fine tune the notch frequency.
5. Fine tune the passband frequency.
NOTCH DEPTH AND FREQUENCY
Notch depth is not normally adjusted when
re-tuning the Series-Notch filter in the field. Notch
depth 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 relative index label is used
to log specific filter performance. Changes in the
notch depth will cause a shift in both the passband
frequency and notch frequency. Smaller notch
depths allow closer spacing of the notch and
passband. Notch depth and notch frequency can
both be checked using the procedure listed below.
Checking the notch depth or frequency
1. A zero reference must first be established at the
IFR A-7550 before the notch depth or frequency
can be measured. This is accomplished by temporarily placing a "female union" between the
generator output and analyzer input, refer to figure 6.
2. Setup the analyzer / generator for the desired
frequency and bandwidth (center of display) and
also a vertical scale of 10 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 assembly. The notch depth and notch frequency
can be read from the display on the IFR
A-7550's screen, see figure 6.
Adjusting the notch depth
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 0 the notch depth will be 15 dB
TX RX Systems Inc. Manual 7-9146-1 07/25/96 Page 3
dB
1
MHZ / DIV
40
98.00 300
MHZ
KHZ RES
center-vertical graticule line on the IFR A-7550's
display). See figure 6.
30
20
10
0
-10
-20
-30
-40
dB
ATT
50
ANALYZER
Used to set 0 dB reference
GEN
dBM
0
FEMALE UNION
20
15
10
5
0
GENERATE
Series-Notch
Filter
MSEC
10
Figure 6: Checking notch depth and notch frequency.
(calibrated by factory). Rotating the loop plate
assembly and moving the calibration mark above 0
causes the notch depth to be increased. It is
adjustable across a useable range of from 15 dB to
25 dB.
Adjusting the notch frequency
The notch depth should be checked and adjusted
prior to adjusting the notch frequency. The
procedure for checking the notch frequency
appears on page 3. Adjustment is made by first
setting the fine tuning knob at it's mid-point. Then
setting the peak (minimum value) of the response
curve to the desired frequency (should be the
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 (5/32 hex wrench required) 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 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
pressure weld that maintains excellent conductivity.
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.
PASSBAND
The passband is the frequency range over
which the return loss is 15 dB or greater.
Because the passband will vary with the tuning of
the notch frequency it should be the last
adjustment made to the Series-Notch filter. The
passband is adjusted by changing the amount of
capacitance in the loop plate assembly. The
capacitor is variable and is either an air-plate or a
tubular-piston type depending upon the frequency
TX RX Systems Inc. Manual 7-9146-1 07/25/96 Page 4
range of the filter. The air-plate type has a red
mark painted on the access barrel and one-half of
the adjusting screw, when the red marks line up
the maximum amount of capacitance is achieved.
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.
A transmitter connected to the filter will operate
best when the reflected energy is lowest. Therefore
a return loss response curve will be used to set the
passband. The passband can be checked and
adjusted following the procedure listed below.
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 7.
2. Set-up the analyzer / generator for the desired
frequency (center of display) and for a vertical
scale of 10 dB/div.
1
dB
MHZ / DIV
40
30
20
10
0
-10
-20
-30
-40
dB
50
ANALYZER
98.00
MHZ
ATT
REFLECTED
GEN
dBM
0
RLB - 150 BRIDGE
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
response 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 8. The display will now present the return loss response curve for the Series-Notch
filter being measured.
Adjusting the passband
The passband is adjusted by turning the variable
capacitor in the loop plate assembly to obtain the
maximum return loss at the desired frequency or
for a maximum return loss across the frequency
band. Because of the filters sensitivity to tool
contact, an insulated tuning tool must be used to
make the adjustment.
MULTIPLE CAVITY SERIES-NOTCH FILTERS
Series-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 the amount of attenuation provided
by each of the filters is additive.
SOURCE
LOAD
Also, the interconnecting cable between the two
filters, when cut to the correct length (odd multiple
of 1/4 λ), will provide up to 6 dB of phase addition
due to a mismatch of impedance between the
cable and the filters. The 6 dB of mismatch
Figure 7: Setting the return loss reference.
TX RX Systems Inc. Manual 7-9146-1 07/25/96 Page 5
attenuation does not occur at the filters passband
but, only at frequencies where moderate to high
attenuation occurs, such as at the 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.
1
dB
MHZ / DIV
40
30
20
10
0
-10
-20
-30
-40
dB
ATT
50
ANALYZER
Series-Notch
Filter
RLB - 150 BRIDGE
REFLECTED
20
15
10
5
0
GEN
98.00
MHZ
dBM
0
SOURCE
LOAD
50 ohm Load
300
KHZ RES
MSEC
10
GENERATE
When tuning a multi-cavity arrangement, each filter
is tuned individually prior to interconnecting. Then
each is fine tuned to peak the overall response of
the 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.
Series- Notch
Filter Part #
20-28-01/-11
20-28-05/-25
20-29-01/-11
20-29-05/-25
20-35-01/-11
20-35-05/-25
20-36-01/-11
20-36-05/-25
20-37-01/-11
20-37-05/-25
20-65-01/-11
20-65-05/-25
20-69-01/-11
20-69-05/-25
20-70-01/-11
20-70-05/-25
Note: The last two digits of the filters model number indicate it's
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.
Vari-Notch
( Lowpass )
Conversion
Kit Part #
Vari-Notch
( Highpass )
Conversion
Kit Part #
Bandpass
Conversion
Kit Part #
T-Pass
Conversion
Kit Part #
76-28-02 76-28-03 76-28-01 76-28-07
76-29-02 76-29-03 76-29-01 76-29-07
76-35-02 76-35-03 76-35-01 76-35-07
76-36-03 76-36-04 76-36-01 76-38-01
76-37-03 76-37-04 76-37-01 76-38-01
76-65-03 76-65-01 76-67-01
76-69-03 76-69-01 76-67-01
76-70-03 76-70-01 76-67-01
Table 2: Conversion kit part numbers.
Figure 8: Checking passband frequency.
TX RX Systems Inc. Manual 7-9146-1 07/25/96 Page 6
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.
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
400 - 512 MHz Band
subtract 6 dB
subtract 3 dB
no correction
add 4 dB
add 5.5 dB
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.
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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