Microwave Test Bench is precision made microwave systems, which use standard type rectangular wave-guide components to illustrate the essential elements of this field for study.

The equipment consist of :

  1. A selection of wave-guide components
  2. The Power Supply for the microwave source
  3. A detector
  4. A Demo Video CD
  5. Audio Communication
  6. Provided with PC to PC communication in Gunn based Benches
  7. Wall Chart

Technology Learning Software – Microwave Fundamentals

Microwave Fundamentals software is very powerful tool to understand core concept of Microwave Technology, throw high quality Simulation, rich theoretical content and attractive animated diagrams.

It covers following topics.

  • Electromagnetic Wave
  • Basics of Electromagnetic waves
  • Wave Guide

Microwave Component Technical Specifications

Gunn Oscillators are used to generate the microwave signal and its Micrometer is used to tune the output frequency of Gunn oscillator.

Band :X
Frequency(GHz) :8.2-12.4
Waveguide: WR-90
Flange:UG-39/U
Bias Voltage max.: 10V
Normal Power Output: 10mW
Output Connection :BNC(F)
Frequency Adjustment:By Micrometer

Waveguide Twist is used to change the plane of Polarization of a wave Guide transmission line . Twist is made from a section of waveguide which has been precisely twisted. 900 twist is a standard available model.

Band X
Frequency(GHz) 8.2-12.4
Waveguide WR-90
Flange UG-39/U
VSWR 1.09 At 10.5GHz
Return Loss -26.9dB At 10.5GHz

Matched terminations are used to terminate the waveguide transmission line operating at low average power. The loads are carefully designed to absorb all the applied power and VSWR of matched termination is low. These are used in the measurement of reflection coefficient and where the matched load is required.

Band X
Frequency(GHz) 8.2-12.4
Waveguide WR-90
Flange UG-39/U
VSWR 1.03 At 10.5GHz
Return Loss -33dB At 10.5GHz
Av. Power 2W
Type Fixed

Movable shorts are used to obtain a phase reference in the calibration of various experimental setups .These are also used to vary the effective plane of reflection and therefore the phase of reflected wave. Movable shorts are used to measure the impedance of a device. Movable shorts are of two types:

  • one has no provision to record position of short in the waveguide
  • other type of movable short is precision movable short in which position of short can be accurately recorded from micrometer

Band X
Frequency(GHz) 8.2-12.4
Waveguide WR-90
Flange UG-39/U
Reflection
Coefficient 0.98

 

Many applications require phase shift to be introduced between two given position in a waveguide system. It consists of a dielectric slab or vane specially shaped to minimize reflection effect. Phase shifter are used to change the effective electrical length of transmission line without changing its physical length.They are particularly useful in microwave bridge circuit where the phase and amplitude must be adjusted independently

Band X
Frequency(GHz) 8.2-12.4
Waveguide WR-90
Flange UG-39/U
VSWR 1.15 At 10.5GHz
Return Loss -23.1 At 10.5GHz
Calibration
Accuracy ±2.5°

Tunable probes are very useful devices to measure the SWR and Impedances. Tunable probe is consists of a crystal detector and a small wire antenna in coaxial housing. Its depth of penetration into the slotted section is variable.

Band X
Frequency(GHz) 8.2-12.4
Detector IN23
Output
connector BNC(F)
Type Tunable

Slide Screw Tuner is a very useful component in a microwave laboratory. It is mainly used for Impedance measurement. Its tuner can be adjusted for low and high impedance position.

 

Band X
Frequency(GHz) 8.2-12.4
Waveguide WR-90
Flange UG-39/U
Max. VSWR 20 : 1.02

Klystron mounts are used to transmit microwave power from reflex klystron tube to rectangular waveguide. Klystron mounts are designed by a section of waveguide, one end of waveguide is fitted with a movable short plunger. A small hole on the broad wall of waveguide is provided through which coupling pin of reflex klystron tube enters into the waveguide. By moving plunger (matching the impedance of klystron tube and waveguide) maximum output can be achieved.

Band X
Frequency(GHz) 8.2-12.4
Waveguide WR-90
Flange UG-39/U

 

Pin diode modulators are used to provide amplitude or pulse modulation in wide range of microwave to study many applications. These modulators uses PIN diode which is mounted across the waveguide line with RF isolated DC bias lead passing to an external TNC(F).

Band X
Frequency(GHz) 8.2-12.4
Waveguide WR-90
Flange UG-39/U
Bias Voltage 0-12 Vpp
Output Connector TNC(F)

 

Direct Reading frequency meters are used to measure the microwave frequency accurately. There long scale length and numbered calibration marks provide high resolution which is particularly useful when measuring frequency difference of small frequency changes.

 

10 dB / 20 dB

Band X
Frequency Range(GHz) 8.2-12.4
Waveguide WR-90
Flange UG-39/U
VSWR Max. 1.25 At 10.5GHz
Av. Power 2 W
Return Loss -19.23 At 10.5GHz

Adaptors transform waveguide impedance to coaxial impedance. Adopters consist of a short section of waveguide with a probe transition mounted on broad wall. Power can be transmitted in either direction. Each adaptor covers the 50% of the waveguide.

 

Band X
Frequency Range(GHz) 8.2-12.4
Waveguide WR-90
Flange UG-39/U
Connector N Type (F)
VSWR Max. 1.12 At 10.5GHz
Return Loss -24.5 At 10.5GHz

 

Attenuators are required to adjust power or attenuate the power flowing in waveguide.There are two type of attenuators fixed and variable. Fixed attenuators available in various range like 3dB,6dB,10dB etc. These attenuators are calibrated at center frequency of respective frequency band. By Variable attenuators power can be adjusted for different level.

Band X
Frequency Range(GHz) 8.2-12.4
Waveguide WR-90
Flange UG-39/U
VSWR Max. 1.06 At 10.5GHz
Av. Power 2W
Accuracy ± 0.5 dB
Return Loss -31 dB At 10.5GHz

 

In measurements it is often necessary to bend a waveguide by some angle. Waveguide bends in E and H plane of 90° is normally available. Waveguide bends designed by a section of rectangular waveguide and flange.

Band X
Frequency Range(GHz) 8.2-12.4
Waveguide WR-90
Flange UG-39/U
VSWR Max. 1.25 At 10.5GHz
Return Loss -25.7 dB At 10.5GHz

Cross Directional Coupler consists of two waveguide sectional joint at (90°) with the coupling element mounted into the common broad wall.

Band X
Frequency Range(GHz) 8.2-12.4
Waveguide WR-90
Flange UG-39/U
Coupling (dB) 20 dB
Directivity (Min) 25 dB
Coupling Accuracy ± 1 dB

Band X
Frequency Range(GHz) 8.2-12.4
Waveguide WR-90
Flange UG-39/U
VSWR Max. 1.06 At 10.5GHz
Return Loss -31 dB At 10.5GHz

Directional coupler are designed to measure incident and reflected power values and also provide a signal path to a receiver or perform other desirable operation. In its most common form, the directional coupler is a four fort waveguide junction consisting of a primary main waveguide and a secondary auxiliary waveguide. These are available in 3, 6,10, 20, 40 dB coupling.

Band X
Frequency Range(GHz) 8.2-12.4
Waveguide WR-90
Flange UG-39/U
VSWR Max. 1.06 At 10.5GHz
Return Loss -31 dB At 10.5GHz
Coupling (dB) 10.1 ± 0.6
Directivity (Min) 46.0 dB (3%)

Band X
Frequency Range 8.2-12.4
Waveguide WR-90
Flange UG-39/U

Band X
Frequency Range(GHz) 8.2-12.4
Waveguide WR-90
Flange UG-39/U

Band X
Frequency Range(GHz) 8.2-12.4
Waveguide WR-90
Flange UG-39/U
Max. Length of cell 200 mm
Plunger Movement 65 mm

The crystal detector can be used for the detection of microwave signal. At low level of microwave power, the response of each detector approximates to square law characteristics and may be used with a high gain selective amplifier having a square law meter calibration.

Band X
Frequency Range(GHz) 8.2-12.4
Waveguide WR-90
Flange UG-39/U
Detector IN21(any
equivalent)
Output Connector BNC (F)

The ferrites isolators and circulators are matched 2 port and 3 port devices respectively, which offer low insertion loss and high isolation over 1GHz band width. An isolator is a 2 port device which allows signals from port 1 to port 2 & provides maximum attenuation for transmission from port 2 to 1. A circulator is a three port device which has a peculiar property of coupling power to the adjacent port clockwise

Band X
Frequency Range 8.2-12.4
Waveguide WR-90
Flange UG-39/U
Max. VSWR 1.15
Min. Insertion Loss 0.46 dB
Min. Isolation 20 dB
Return Loss 22.4

Micrometer type frequency meters are consists of a microwave cavity with plunger and a section of waveguide. It consists of a micrometer to measure its position for measuring frequency.

Band X
Frequency Range 8.2-12.4
Waveguide WR-90
Flange UG-39/U
Max. VSWR 1.15
Calibration Accuracy ± 2 %
Calibration Increment 10 MHz

There are several types of microwave antennas like standard Gain, Pyramidial horn, Pick up horn, Dielectric antenna, Parabolic dish
antenna etc. these are used to radiate microwave energy in the air and to receive the energy from air.

Frequency Flange Waveguide Antennas Gain
Range(GHz) Designation Type Type
8.2-12.4 GHz UG-39/U WR-90 Pyramidal 16
8.2-2.4 GHz UG-39/U WR-90 Pick Up 10
8.2-12.4 GHz UG-39/U WR-90 E-Section 15
8.2-12.4 GHz UG-39/U WR-90 H-Section 15
8.2-12.4GHz UG-39/U WR-90 Parabolic dish --
8.2-12.4GHz UG-39/U WR-90 Standard Gain --
8.2-12.4GHz UG-39/U WR-90 Dielectric Antenna --

Slotted section is used to measure various measuring parameter in microwave. for example to determine VSWR, phase and impedances. These consists of a slot in center of waveguide in which we can connect a probe and probe can be moved in slot and position of probe can be measured by its Varnier scale. The travel of probe carriage is more than three times of half wavelength.

Band X
Frequency Range 8.2-12.4
Waveguide WR-90
Flange UG-39/U
Residual VSWR 1.01
Slope (dB) ± (0.2dB)

List of  Components

Experiments that can be performed

  • Study of the characteristics of klystron tube and to determine its electronic tuning range
  • To determine the frequency & wavelength in a rectangular waveguide working on TE mode 10
  • To determine the standing wave ratio and reflection coefficient
  • To measure an unknown impedance with Smith Chart
  • To study the square law behaviour of a microwave crystal detector
  • To study the voice communication by using microwave test bench
  • To study the variable attenuator
  • To measure the polar pattern and the gain of following antennas
    •  Standard Gain Horn – Pick up horn
    • Slotted Broad Wall – Slotted Narrow Wall
    • Dielectric Antenna – E-plane Sectorial Horn
    • H-Plane Sectorial Horn – Pyramidal Horn – Parabolic Dish
  • To study the square law behaviour of a microwave crystal detector.
  • To study the voice communication by using microwave test Bench.

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