Our Coaxial cavity filters

1. COAXIAL CAVITIES
Box 22 Tel. +358 9 2790 120 http://www.aerial.fi
04401 Järvenpää Fax +358 9 2910 210 aerial@aerial.fi
Finland
DESCRIPTION
Aerial Oy supplies coaxial cavity resonators for filter
applications. Different kinds of cavity circuit
combinations can be constructed to reject interfering
frequencies or to isolate receivers or transmitters
when using a common antenna.
Power rating, transmission and VSWR values
depend on the selected cavity combination, filtered
frequencies, interconnection cable and connector
types which are all agreed with the customer. Tuning
is factory-made at Aerial Oy premises unless agreed
otherwise.
COAXIAL CAVITIES
MECHANICAL AND ELECTRICAL DATA
Type CR110-75 CR110-95 CR200-95 CR110-120 CR110-150 CR110-450
Tuning range 68-88 MHz 88-108 MHz 88-108 MHz 118-144 MHz 146-174 MHz 380-470 MHz
RF-connector N female N female 7/16 female N female N female N female
Diameter ∅ 110 mm ∅ 110 mm ∅ 200 mm ∅ 110 mm ∅ 110 mm ∅ 110 mm
FEATURES
§ Available as single cavity or multicoupler
§ Passive element à minimum maintenance,
maximum power
§ Temperature drift compensated by using Invar
steel as a conductor piston (tuning rod) material.
§ Constructed and tuned individually according to
the customer’s order
§ Materials: Aluminium alloy and silver plated brass
§ Colour: Light grey
§ High power version CR200-95 available for FM
§ Installation between antenna and receiver(s) or
transmitter(s).

2. COAXIAL CAVITIES
Box 22 Tel. +358 9 2790 120 http://www.aerial.fi
04401 Järvenpää Fax +358 9 2910 210 aerial@aerial.fi
Finland
TRANSMISSION CURVE
CR150-1, Single cavity
-80
-70
-60
-50
-40
-30
-20
-10
0
-1 0 1 2 3 4 5
f [MHz]
Transmission[dB]
-0,5 dB -1 dB -2 dB -3 dB
TRANSMISSION CURVE
CR150-2, Two cavity combination
-80
-70
-60
-50
-40
-30
-20
-10
0
-1 0 1 2 3 4 5
f [MHz]
Transmission[dB]
-1 dB -2 dB -4 dB -6 dB
TRANSMISISON CURVE
CR150-3, Three cavity combination
-80
-70
-60
-50
-40
-30
-20
-10
0
-1 0 1 2 3 4 5
f [MHz]
Transmission[dB]
-1,5 dB -3 dB -6 dB
BANDPASS FILTERS
Shape and steepness of the transmission curve
can be adjusted by selecting the most suitable
out of four possible positions of the coupling
loops which are situated in the front panel of the
cavity (see the picture below). However using
radical coupling affects also the bandpass
attenuation so this feature has to be used
deliberately.
Adjustable loops are available for cavities with N-
connectors only.
Illustrating example curves of one, two and three
cavity circuits with different loop settings are below.

3. COAXIAL CAVITIES
Box 22 Tel. +358 9 2790 120 http://www.aerial.fi
04401 Järvenpää Fax +358 9 2910 210 aerial@aerial.fi
Finland
NOTCH FILTERS
To reject interfering spot frequencies coaxial cavity
circuits can be tuned as notch filters. Some examples of
possible 146…174 MHz range patterns are below:
TRANSMISSION CURVE
CR150-1 Notch filter, single cavity
-30
-25
-20
-15
-10
-5
0
-3 -2 -1 0 1 2 3
f [MHz]
Transmission[dB]
TRANSMISSION CURVE
CR150-2 Notch filter, Two cavities
-60
-50
-40
-30
-20
-10
0
-3 -2 -1 0 1 2 3
f [MHz]
Transmission[dB]
TRANSMISSION CURVE
CR150-1 Notch filter, single cavity
-25
-20
-15
-10
-5
0
-3 -2 -1 0 1 2 3
f [MHz]
Transmission[dB]
TRANSMISSION CURVE
CR150-2 Notch filter, Two cavities
-60
-50
-40
-30
-20
-10
0
-3 -2 -1 0 1 2 3
f [MHz]
Transmission[dB]
TRANSMISSION CURVE
CR150-1 Notch filter, Single cavity
-25
-20
-15
-10
-5
0
-3 -2 -1 0 1 2 3
f [MHz]
Transmission[dB]
TRANSMISION CURVE
CR150-2 Notch filter, Two cavities
-60
-50
-40
-30
-20
-10
0
-3 -2 -1 0 1 2 3
f [MHz]
Transmission[dB]

4. COAXIAL CAVITIES
Box 22 Tel. +358 9 2790 120 http://www.aerial.fi
04401 Järvenpää Fax +358 9 2910 210 aerial@aerial.fi
Finland
Antenna
Input Input
DUPLEXERS (MULTICOUPLERS)
Duplexer circuits can be used to couple multiple receivers
or transmitters to a common antenna. This following
measured example graph is a FM duplexer which
couples two local radio transmitter feed signals together
for common feed cable and antenna system. The block
diagram of the system is on the right.
f1 = 105,2 MHz
f2 = 107,7 MHz
Bandpass attenuation 0,6 dB
Isolation 45 dB
System return loss can be matched better than 20 dB for
a ±100 kHz frequency band.
TRANSMISSION CURVE
2 x CR200-95-2 Duplexer
-50
-45
-40
-35
-30
-25
-20
-15
-10
-5
0
104 105 106 107 108 109
f [MHz]
Transmission[dB]
ORDERING INFORMATION
To order a correct filter type please contact our sales
personnel and be prepared to inform us about the
frequencies, bandwidths, Return loss values, power
handling, bandpass and band reject attenuation or
isolation which are required in your system. You can also
leave the decision to our skilled engineers.