EC-406MICROWAVE ENGINEERING LAB

Submitted by: Manshul Arora ECE-II (7TH SEM) 78/EC/11 manshularora00@gmail.com

LIST OF EXPERIMENTS

S.No.ExperimentSignature

1To study various microwave components and instruments.

2Setup an experiment to study the characteristics of Klystron tube.

3Setup an experiment to measure the frequency and wavelength of microwave signal.

4To determine SWR and reflection coefficient.

5Setup an experiment to study the function of phase shifter.

6Setup an experiment to study the function of Magic Tee.

7Setup an experiment to study the function of circulator/isolator.

8Setup an experiment to study the function of directional coupler.

9Using Microwave Communication kit, setup an experiment to study the following:(a) HPBW measurement(b) Polarization and Reflection of microwave(c) Measurement of gain with and without waveguide

10Draw the magnitude response & phase response of S21 & S11 using MATLAB for frequency 0 to 10 GHz for the following circuit.

11Draw the magnitude response & phase response of S21 & S11 using MATLAB for frequency 0 to 10 GHz for the following circuit.

12Draw the magnitude and phase response of S11 and S21 using MATAB for the given circuit.

EXPERIMENT-1

AIM: To study various microwave components and instruments.

Adaptors (Coaxial To Waveguide) - These adapters consist of a short section of waveguide with a probe transition coax mounted on broad wall. It transforms waveguides impedance into coaxial impedance. Power can be transmitted in either direction. Each adaptor covers 50% of the waveguide band.

Attenuators - Required for adjusting the power flowing in a waveguide. There are a broad range of fixed, variable and rotary vane attenuators in waveguide. Fixed: Any amount of fixed attenuation can be supplied between 3 to 40 dB. These attenuators are calibrated frequency band. Variable: Variable attenuators provide a convenient means of adjusting power level very accurately. Rotary: The rotary vane attenuators are the ideal instrument for use in waveguide systems where broad band direct reading of attenuation is required, particularly as a standard for reflecto-meter and swept measuring systems.

Bends - In measurement it is often necessary to bend a waveguide by some angle. SICO offers 771 & 775 series of 90 waveguide bends in E and H plane respectively. Although for special requirement we can provide bending angle 30, 45, 60, and 120 in either plane. These bends incorporate a bend waveguide section and two standard flanges.E & H metered Bends: These are the waveguide metered bend in E plane of H plane

Detector Mounts - The crystal detector can be used for the detection of microwave signal. SICO 460 series tuned broad band and 451 series tunable waveguide detectors. RF choke is built into the crystal mounting to reduce leakage from BNC connector. Square law characteristics may be used with a high gain selective amplifier having a square law meter calibration.At low level of microwave power, the response of each detector approximate to square law characteristics and may be used with a high gain selective amplifier having a square law meter calibration.

Couplers - At Microwave frequencies the directional couplers are an easy tool to sample the microwave energy travelling in one direction.Attenuation measurement, reflect meter setup, power measuring, source leveling and network analysis are just a few areas in which couplers are used. Multi Hole Directional Couplers: SICO offers 6 xx series directional couplers which are multi-element couplers built from a rectangular waveguide. (xx: Stands for the value of coupling in dB). Cross Directional Coupler: Cross directional couplers consist of two waveguide sectional joint at 90 with the coupling element mounted into the common broad wall. Each model is furnished with a nominal mid band coupling value of 20 dB. On special order other coupling valve can also be supplied.

Dielectric Cells - The Model 501 and 701 are basic measuring components for solid and liquid dielectric constant measurement respectively. These consist of cavities for keeping the sample and the position of the sample can be read by means of micrometer.

Ferrite Isolators and Circulators - These ferrite isolators & circulators are matched 2 port/3 port devices which offer low insertion loss and high isolation over 1 GHz band width. The performance of these Isolators optimizes at the frequency given in the datasheet on special order. A unit can be optimized at any frequency within the wave guide band.

Frequency Meter - These (reaction cavity type) frequency meters are intended for moderate accuracy applications in microwave measurements and usually best for this purpose since these permit full power flow down the transmission line except at the precise tuned frequency.Frequency Meter (Micrometer type): The frequency meter model 455 consists of a microwave cavity with plunger and a section of standard waveguide. The micrometer drive of plunger ensures precise control of its position enabling frequency measurement with high accuracy.Direct Reading frequency Meter: These direct reading frequency meters model 710 measure frequencies accurately. Their long scale length and numbered calibration marks provide high resolution which is particularly useful when measuring frequency differences of small frequency changes.

Waveguide Horns - SICO offers a series of standard Pyramidal, Sectorial and pickup Horn. These are intended for use in general purpose radiators and are also used to determine the gain of antenna under test by a conventional substitution method. They are also used as reference sources in dual channel antenna test receivers and can be used as pick up horns for radiation monitoring.

Klystron Mounts - 251 Series of Klystron mounts are used to provide easy mean of transmission of microwave power from reflex Klystron tube to the rectangular waveguide systems. It consists of a section of waveguide whose one end is fitted with moveable 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. The maximum power transfer is achieved by matching the impedance of waveguide & Reflex Klystron tube through movable plunger.

Tuners - E-H plane Tuners provides a convenient means of tuning out discontinuities in waveguide systems. Mismatches up to 20:1 can be tuned to a VSWR of less than 1.02 at any frequency in the waveguide band.

Phase Shifter - Phase shifters 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 phase and amplitude must be adjusted independently. The phase shift is controlled by a micrometer driven mechanism which assure optimum resolution in each waveguide. The unit is supplied with a calibration chart of centre frequency of each band on request.

Probes - These are very important tools for measuring the SWR and impedance.655 Tunable probes: SICO 655 series tunable probe consists of a crystal, plus a small wire antenna in convenient coaxial housing. Its depth of penetration in to the slotted section is variable and may be locked at any position of penetration. Broad Band probe: It consists of a crystal diode plus a small antenna probe in a suitable housing for sampling microwave energy. This probe is extremely sensitive over a wide frequency range. No tuning is required for maximizing the sampled signal.

Shorts - Moveable Short is used to obtain a phase reference in the calibration of various experimental set-ups & is also used to vary the effective plane of reflection and therefore the phase of reflected wave. These are also useful for impedance measurement. SICO offers two types of shorts: Series 481 are general purpose short known as moveable short in which there is no provision to record the position of short in the waveguide Series 581 precision types short known as precision short in which position of short can be accurately recorded from micrometer attached to it.

Slotted Line With Probe Carriage - The slotted line represented the basic instrument of microwave measurements. With its help it is possible to determine the VSWR, attenuation, phase and impedances. The position of carriage (probe) can be read from a scale with its vernier. The total travel of probe carriage is more than three time of half of guide wavelength.

.Terminations - These are designed for terminating the waveguide Systems operating at low average power. The loads are carefully designed to absorb virtually all the applied power and assure a low SWR. They may be used where a matched load is required as in the measurements of reflection, discontinuities of obstacle in waveguide systems.

Accessories - Universal Waveguide Stand, Choke flanges are available for all bands. Required for maximizing the sampled signal.Cable of one meter length is available with the following connectors. BNC, TNC, UHF, N type, SMA.

Modulators - Many applications of microwave testing require amplitude modulation and pulse modulation of signal sources. Pin Diode modulators offer an ideal way of amplitude & pulse modulation of microwave signal though a wide range of frequencies. These modulators utilize PIN Diode which is mounted across the waveguide line with an R.F. isolated DC bias lead passing to an external TNC (F) connector.

Oscillator (Gunn) - These mechanically tuned Gunn Oscillators provide a low highly reliable source for generating the microwave signal.

Twists - These are used to rotate the plane of polarization of a waveguide Transmission line. Twists are manufactured from a section of standard waveguide which has been precisely twisted maintaining the internal waveguide dimension. Standard Model is 90 twist. Other configurations are available on special order for different angle and overall length.

TEES - SICO offers different series of waveguide Tees. These are used to divide Microwave energy from one input into two output lines, or to combine microwave energy from two inputs into one output.

EXPERIMENT-2

AIM: Setup an experiment to study the characteristic of Klystron tube.

APPARATUS REQUIRED: Klystron power supply SKPS 610, Klystron Mount XM251, Isolator, Frequency Meter XF-710, Variable Attenuator XA-520, Detector Mount XD 451, Waveguide Stand XU- 535, VSWR Meter SW- 215, Oscilloscope and BNC Meter.

BLOCK DIAGRAM:

Klystron Power SupplyMicrowave sourceIsolatarFrequency MeterVariable AttenuatorDetector MountMultimeterMatched TerminationOscilloscopeTHEORY:The reflex klystron tube makes the use of the velocity modulation to transform a continuous electron beam into microwave power electrons emitted from the cathode are accelerated and passed through the positive resonator towards negative reflector which retards and reflects the electrons end the electron turns back through the resonator. The accelerated electrons have the resonator at a higher frequency. The electrons leaving the resonator will med. diff. time to return, due to change in velocities. As a result, returning electrons group together in bunches. As the electrons bunch pass through resonator, they interact with voltage at the resonator grids if the bunches pass the grid at such time that the electrons are slowed down by voltage, energy will be delivered to the resonator and klystron will oscillate.The dimensions of resonant cavity primarily determine the frequency. Hence by changing the volume of the resonator mechanical tuning range of klystron is possible. Also a small frequency change can be obtained by adjusting the reflector voltage. This is called Electronic Tuning.

PROCEDURE:1. The components are connected as shown in the figure.2. The variable attenuators are set at the maximum position.3. The mod switch of klystron supply tube is set to the CW position. 4. Beam voltage control knob to fully anti-clockwise and reflector voltage control knob to fully clockwise. Meter switch is OFF. The knob of frequency meter is rotated to one side fully. The klystron power supply is turned ON.5. The DC microampere meter is connected with detector.6. The beam voltage switch is put on and the beam voltage knob is rotated clockwise slowly up to 300V meter reading and the beam current is observed on the meter by changing the meter switch to beam current position. 7. The beam current should not increase more than 300mA.8. The reflector voltage is changed slowly and the current meter is watched for maximum deflection in the meter.9. The plunger of the klystron mount is tuned for the maximum output.10. The knob of frequency meter is rotated slowly and stopped at the position there is less output on multimeter.11. This observation can also be done on an oscilloscope.Square Wave Operation:The equipments were connected as shown in the figure. The micrometer of variable attenuator was set around some position. The range switch of VSWR meter was set at 40dB position, the input selector switch to crystal impudence position, meter switch to narrow position. The mod selector switch was set to AM-MOD position, the beam voltage control knob to fully anti-clockwise position. The Klystron power supply, VSWR meter and cooling fan were switched ON. The beam voltage switch was switched ON and the beam voltage knob was rotated clockwise upto 295V deflection in meter. The AM-MOD amplitude knob and AM-FRE knob was kept at mid position. The reflector voltage knob was rotated to get deflection in VSWR meter. The AM-MOD amplitude knob was rotated to get the maximum output in VSWR meter. The deflection with frequency knob was maximized to get maximum output in VSWR meter. If required, the range switch of VSWR meter was changed.

Mode Study on Oscilloscope:The components and equipment were setup as shown in fig. The position of variable attenuator was kept at min attenuator position. The mode selector switch was kept fully anticlockwise and beam switch to off position. The time division of oscilloscope was kept around 100Hz frequency measurement and voltage/division to lower scale. The beam voltage switch was switched ON and kept at 295V. The amplitude knob of FM modulator was kept to max position and reflector voltage was rotated to anticlockwise to get on the oscilloscope. The horizontal axis represents the output power. Any mode of Klystron tube can be observed on oscilloscope by changing the reflector voltage and amplitude of the modulation

OBSERVATION TABLE:Repeller VoltageOscilloscope Volt.Freq. (Hz)

RESULT:Repeller VoltagePowermaxFrequency

1. The output power was plotted against the repeller voltage.2. From the graph it was observed that we get a maximum power between two consecutive minima where P = 0.3. The value of Pmax increases with increase in repeller voltage.

EXPERIMENT-3

AIM: Setup an experiment to measure the frequency and wavelength of microwave signal.

APPARATUS REQUIRED: Klystron power supply SKPS 610, Klystron Mount XM251, Isolator, Frequency Meter XF-710, Variable Attenuator XA-520, Slotted Wire (XS-651), Tunable Probe (XP-655), Waveguide Stand XU- 535, VSWR Meter SW- 215, Movable Short (XT-481)/Matched termination (XL400).

BLOCK DIAGRAM:

Klystron Power SupplyMicrowave sourceIsolatorFrequency meterVariable AttenuatorSlotted LineTunable ProbeMatched TerminationMovable shortTHEORY:For dominant TE10 mode rectangular waveguide, g, 0 and c are related by:

Where, 0 = Free space wavelength, g = Waveguide wavelength, c = Cut-off wavelengthFor TE10 mode, c = 2a, where a = Broad dimension of waveguide.

PROCEDURE:1) The components were set up as shown in the figure. The variable attenuator was set up at a minimum attenuation position. The central knobs of VSWR meter were kept as - Range: 50 db, Input Switch Crystal: Low, Meter Switch: Normal position, Gain (coarse/fine): Mid position.2) The control knobs of Klystron power supply were kept as below: Beam Voltage: Off, Mod-Switch: AM, Beam Voltage Knob: fully anticlockwise, Reflector Voltage: fully clockwise, AM amplitude knob: around fully clockwise, AM frequency knob: around mid position.3) The Klystron power supply, VSWR meter and cooling fan are switched on. The beam voltage was switched on and beam voltage was set at 295 volts, with the help of beam voltage knob. 4) Reflector voltage was adjusted to get some deflection in VSWR meter. Deflection was minimized with AM amplitude and frequency control knob of power supply.5) The plunger of Klystron mount in and probe were tuned for maximum deflection. Frequency meter knob was tuned to get a dip on the VSWR scale. 6) The terminator was replaced with movable short. Probe was moved along the slotted line and minimum deflection position to get accurate reading (If necessary, increase the VSWR meter db range switch to higher position). 7) The probe position was noted. Probe was moved to next minimum position and position was recorded again.8) The guide wavelength was calculated as twice the distance between two successive minima positions attained above. The waveguide inner dimension a was measured. Frequency was calculated.

OBSERVATION TABLE:S. No.Repeller Voltage (V)Avg. Difference (cm)g = 2(d1-d2) (cm)c (cm)f = c/0 (GHz)

1

2

3

RESULT:1) The output power was plotted against the repeller voltage.2) From the graph it was observed that we get a maximum power between two consecutive minimas where P = 0.3) The value of Pmax increases with increase in repeller voltage.

EXPERIMENT-4

AIM: To determine SWR and reflection coefficient.

APPARATUS REQUIRED: Klystron tube, Klystron Power supply, VSWR meter, Klystron Mounts, Variable Attenuator, Slotted line, Tunable Probe, Waveguide Stand, Movable Short Termination, BNC cable, SS Tuner

BLOCK DIAGRAM:

THEORY:The electromagnetic field at any position of the transmission line may be considered as the sum of the traveling waves. The incident wave which propagates towards the generator and the reflected wave is generated from a discontinuity in line or from load impedance. The superposition of the two traveling waves results in a stand by wave along the line. The maximum field strength is found where the waves are in phase and min., where the two waves are out of the phase, and the distance between two successive minimas is half the wavelength of guide. The ratio of the incident field and the reflected wave is known as the reflection coefficient.The VSWR is the ratio between the maximum and minimum field strength along the line. Hence the VSWR is

Reflection coefficient,

Where, Zi = Load Impedance, and Zo = Characteristic impedance. Therefore,

PROCEDURE:1) The apparatus was set up as shown in figure. The variable attenuation was kept at the minimum attenuation position. The control knobs of VSWR meter were kept as below: Range: 40-50 dB, Input-Switch: Low-Impedance, Meter Switch: Normal, Gain (Coarse fine) - Mid-position approx.2) The control knobs of the klystron power supply were kept as below Beam Voltage - 0FF, Mod-Switch- AM.3) The beam voltage, klystron power supply, VSWR cooling fan are switched ON.4) The beam voltage is set at 295V. The reflector voltage knob was rotated to get deflection in VSWR meter. The o/p was tuned by tuning the reflector voltage amplifier and frequency of AM modulation. The plunger of Klystron Mount and Probe were tuned for maximum deflection in VSWR meter.Measurement of High VSWR:

5) The depth of SS tune was set slightly more for maximum VSWR. The probe was moved along a slotted line until a minimum was indicated. The VSWR meter gain of knob and variable attenuator was adjusted to obtain a reading of 3dB in the normal dB scale (0-10dB) of VSWR meter. The probe was moved to the left on the slotted line until a full scale deflection was obtained on 0-10dB scale. The probe position is noted as d1. Note another position as d2. The SS tuner and terminator were replaced by movable short. Found and SWR is calculated as

OBSERVATIONS:Emax=Emin=

RESULT:1) The standing wave ratio as compared from the observation table is2) The value of the reflection coefficient r is

EXPERIMENT-6

AIM: Setup an experiment to study the function of Magic Tee.

APPARATUS REQUIRED: Microwave source, Isolator (2K25), Variable Attenuator XA520, Frequency Meter XF7110, Slotted Line XS651, Tunable Probe XP-655, Magic Tee, Detector Mount XD451.

BLOCK DIAGRAM:

THEORY:

The device magic tee is a combination of the E and H plane. Arm 3 is H arm and arm 4 is E arm. If the power is fed into arm 3 (H arm), the E divides equally between arm 1 and arm 2 with the same phase and no electric field exists in arm 4. If the power is fed into arm 1 and arm 2 simultaneously it is added in arm 3 (H arm) and is subtracted in E arm.

PROCEDURE:VSWR measurements of the ports1. Set up the experiment as shown.2. Start Klystron Tube.3. Measure the VSWR of E arms as described in measurement of SWR for low and medium value.4. Connect another arm to slotted line and terminate the other port with the matched terminator. Measure VSWR.

Measurement of isolation N coupling factor1. Remove the tunable probe and magic tee from slotted line and connect the detector mount to the slotted line.2. Start Klystron tube.3. Set any power level in VSWR meter and note it down. Let it be P3.4. Without disturbing the position of variable attenuator to gain control knobs place the magic tee after slotted line keeping the arm connected to slotted line, detector to E arm and matched termination to arm 1 and arm 2. Note down VSWR reading. Let it be P4.5. Determine isolation between port 3 and port 4 by P3 -P4 in dB.6. Determine coupling coefficient.7. The same experiment is repeated for other ports.

The basic parameters to be measured:1. Input VSWR: Value of SWR corresponding to each port, as a load to the line while other ports are terminated in matched load.2. Isolation: The isolation between E and H arms is defined as the ratio of the power supplied by the generator connected to the E arm to the power detected at the H arm when 1 and 2 are terminated using matched load.3. Coupling factor: It is defined as Cij = 10 /20 where is the attenuation/isolation in dB when it is input arm and j is output arm. = 10log10(P4/P3).

OBSERVATIONS:1. Beam Voltage=2. Repeller Voltage =3. Power= 2.1 * =4. Power in H arm =5. Power in E arm =

EXPERIMENT-9

AIM: Using Microwave Communication kit, setup an experiment to study the following:(a) HPBW measurement(b) Polarization and Reflection of microwave(c) Measurement of gain with and without waveguide

APPARATUS REQUIRED: Microwave satellite communication base, Microwave transmitter, Microwave receiver, Power supply load, Metal polarization grid, Cardboard, Metal satellite.

THEORY:Polarization:Microwaves are electromagnetic waves containing energy associated with electric and magnetic fields each of these fields have a transverse motion.Angle of electric field with respect to direction of propagation, decide the polarization of wave. Electric field if stays in one plane during propagation of wave i.e. called plane polarized. For an antenna, the electric field runs parallel to antenna, the electric field runs parallel to antenna and the magnetic field goes perpendicular to it .In horn antenna, Vertically plane polarized waves are generated by an oscillator and is launched into the waveguide. The received signal will have maximum intensity when receiver antenna is properly aligned with the transmitter and minimum when they are 90 with each other.

Microwave reflection:When waves are in space, they spread across a wide area. So in open space a lot of energy is lost. The best way to prevent this is to send it via a metal tube beam being reflected by waveguide walls. Most metals reflect microwaves through with some amount of conduction losses.

Waveguide:A hollow metallic tube of uniform cross-section of transmitting EM waves by successive reflections from the inner walls of the tube is called a waveguide. There is a cut off value for frequency of transmission depending upon the dimensions of waveguide.

Gain and half power beam width:The fundamental characteristics of an antenna are its gain and half power beam width. According to reciprocity theorem, the transmitting and receiving patterns of antenna are identical at a given wavelength. The gain is a measure of how much of the input power is concentrated in a particular direction. It is expressed with respect to a hypothetical isotropic antenna, which radiates equally in all directions.Thus in the direction (,) gain is

Maximum gain is along the bore sight direction. Z0 = impedance of free space.Bore sight gain is given in terms of size of antenna.

For circular reflection .Gain increases as wavelength decreases or frequency increases.Half power beam width is angular separation between half power points on the antenna radiation pattern, where the gain is one half the maximum value: HPBW= k/D HPBW decreases with decreasing wavelength and increasing diameter.

OBSERVATION TABLE:

a) Gain with and without waveguide

TransmitterReceiver (without waveguide)Receiver (with waveguide)

b) Half Power Beam Width

AngleReceiver

(transmitter is set at 5)

RESULT:As can be seen from the observation tables, gain increases in presence of a waveguide as opposed to without waveguide.Also it was seen that HPBW = When conducting rods are placed vertically in between the transmitter and receiver, the receiver reading is minimum. As the rods are rotated, the receiver reading increases till it reaches a maximum value when the rods are horizontally placed. Thus vertical plane is the E-plane and horizontal plane is the H-plane.

EXPERIMENT-10

AIM: Draw the magnitude response & phase response of S21 & S11 using MATLAB for frequency 0 to 10 GHz for the following circuit.

CIRCUIT:

CODE:

%%%% Microwave LPF %%%% clear all;close all;clc; %% Characteristic Impedance %%Z0 = 50; C1 = 0.984*10^(-12);L2 = 6.438*10^(-9);C3 = 3.183*10^(-12);L4 = L2;C5 = C1; f=1:0.1*10^9:10*10^9; for i=1:1:length(f) w = 2*pi*f(i); %% ABCD Matrix of individual elements %% T1 = [1 0; j*w*C1 1]; T2 = [1 j*w*L2; 0 1]; T3 = [1 0; j*w*C3 1]; T4 = [1 1i*w*L4; 0 1]; T5 = [1 0; j*w*C5 1]; %% Cascading %% T = T1*T2*T3*T4*T5; A = T(1,1); B = T(1,2); C = T(2,1); D = T(2,2); S21(i) = 2/(A + B/Z0 + C*Z0 + D); S11(i) = (A + B/Z0 - C*Z0 - D)/(A + B/Z0 + C*Z0 + D); i = i+1;end subplot(2,1,1);plot(f,abs(S11),'r-',f,abs(S21),'b-');title('Magnitude Response');xlabel('Freqency --->');ylabel('Magnitude ---->');subplot(2,1,2);plot(f,angle(S11),'r*',f,angle(S21),'bx');axis([0 10*10^9 -pi pi]);title('Phase Response');xlabel('Freqency --->');ylabel('Phase ---->');OUTPUT:

OBSERVATION:

The given circuit is a microwave low-pass filter with cut-off frequency = 2 Ghz.

EXPERIMENT-11

AIM: Draw the magnitude response & phase response of S21 & S11 using MATLAB for frequency 0 to 10 GHz for the following circuit.

CIRCUIT:

CODE:%%%% Microwave BPF %%%% clear all;close all;clc; %% Characteristic Impedance %%Z0 = 50; L1 = 127*10^(-9);C1 = 0.199*10^(-12);L2 = 0.726*10^(-9);C2 = 34.91*10^(-12);L3 = L1;C3 = C1; f=0.6*10^9:10^5:1.4*10^9; for i=1:1:length(f) w = 2*pi*f(i); %% ABCD Matrix of individual elements %% T1 = [1 j*w*L1; 0 1]; T2 = [1 1/(j*w*C1); 0 1]; T3 = [1 0; 1/(j*w*L2) 1]; T4 = [1 0; j*w*C2 1]; T5 = [1 j*w*L3; 0 1]; T6 = [1 1/(j*w*C3); 0 1]; %% Cascading %% T = T1*T2*T3*T4*T5*T6; A = T(1,1); B = T(1,2); C = T(2,1); D = T(2,2); S21(i) = 2/(A + B/Z0 + C*Z0 + D); S11(i) = (A + B/Z0 - C*Z0 - D)/(A + B/Z0 + C*Z0 + D); i = i+1;end subplot(2,1,1);plot(f,abs(S11),'r-',f,abs(S21),'b-');title('Magnitude Response');xlabel('Freqency --->');ylabel('Magnitude ---->');subplot(2,1,2);plot(f,angle(S11),'r-',f,angle(S21),'b-');axis([f(1) f(length(f)) -pi pi]);title('Phase Response');xlabel('Freqency --->');ylabel('Phase ---->');OUTPUT:

OBSERVATION:

The given circuit is a microwave band-pass filter with Bandwidth = (1.061-0.9437) Ghz = 0.1173 Ghz = 117.3 MHz.

EXPERIMENT-12

AIM: Draw the magnitude response & phase response of S21 & S11 using MATLAB for the following circuit.

CIRCUIT:

CODE:

clear all;close all;clc; %% Characteristic Impedances %%Z0 = 50;Z01 = 64.9;Z02 = 217.5;Z03 = 70.3;Z04 = Z02;Z05 = Z01; %% l is fixed, f is varying %%f = [3:0.000001:3.06]*10^9;l = 10;c = 3*10^8; for i=1:1:length(f) theta = 2*pi*f(i)*l/c; T1 = [1 0; j*(1/Z01)*tan(theta) 1]; T2 = [cos(theta) j*Z02*sin(theta); j*(1/Z02)*sin(theta) cos(theta)]; T3 = [1 0; j*(1/Z03)*tan(theta) 1]; T4 = [cos(theta) j*Z04*sin(theta); j*(1/Z04)*sin(theta) cos(theta)]; T5 = [1 0; j*(1/Z05)*tan(theta) 1]; T=T1*T2*T3*T4*T5; A = T(1,1); B = T(1,2); C = T(2,1); D = T(2,2); S21(i) = 2/(A + B/Z0 + C*Z0 + D); S11(i) = (A + B/Z0 - C*Z0 - D)/(A + B/Z0 + C*Z0 + D); i = i+1;end subplot(2,1,1);plot(f,abs(S11),'r-',f,abs(S21),'b-');title('Magnitude Response');xlabel('Freqency --->');ylabel('Magnitude ---->');subplot(2,1,2);plot(f,angle(S11),'r',f,angle(S21),'b');axis([f(1) f(length(f)) -pi pi]);title('Phase Response');xlabel('Freqency --->');ylabel('Phase ---->');OUTPUT: