Microwave Engineering Instructor: Athar Hanif Lecture-3 Microwave Engineering Instructor: Athar Hanif

Quiz-1 Time Allowed: 30 minutes Total Marks: 20 Q.1:A plane wave traveling in z- direction in a dielectric medium with єr =2.55 has an electric field given by Ey = E0 cos(ωt-βz). The frequency is 2.4 GHz, and E0 = 30 V/m. Find the amplitude and direction of the magnetic field. (2 Marks) Find the phase velocity and wavelength. (3 Marks) Find the phase shift between the positions Z1 = 0.5 m and Z2 = 1.7 m. (5 Marks)

Quiz-1 Time Allowed: 30 minutes Total Marks: 20 Q.2: A RFC is constructed by winding four turns of AWG 38 copper wire(σcu =64.516х106S/m) on a 2 mm ceramic core diameter(μr = 1) of 0.1 mm length. Estimate The inductance (3 Marks) Stray capacitance (2 Marks) Resistance (2 Marks) Resonance frequency (3 Marks)

Microstrip Transmission Line Most popular type of planer transmission line Geometry of microstrip line

Microstrip Transmission Line Dielectric were not present(єr =1) Simple TEM waves Dielectric were present(єr ≠1) Does not support TEM waves

Microstrip Transmission Line In practical application, h<<λ Fields are quasi-TEM Єe is the effective dielectric constant 1< єe< єr

Microstrip Design Step-1: find W/h ratio єr and Z0 = known Step-2: For W/h ≤ 2

Microstrip Design For W/h ≥ 2 Step-3: Effective dielectric constant

Microstrip Design Step-4: Find Z0 For W/h ≤ 1 For W/h ≥ 1

Microstrip Design Step-5: (1) Attenuation due to dielectric loss Where tanδ is the loss tangent of the dielectric

Microstrip Design Attenuation due to conductor loss Rs is the surface resistivity of the conductor

Microstrip Design

Microstrip Design

Design Problems Problem-1: calculate the width and the length of a microstrip line for a 50Ω characteristic impedance and a 900 phase shift at 2.5 GHz. The substrate thickness is h = 0.127cm, with єr = 2.20 Problem-2: Design a microstrip transmission line for a 100Ω characteristic impedance. The substrate thickness is 0.158cm, with єr = 2.20. What is the guide wavelength on this transmission line if the frequency is 4.0 GHz.

Assignment Problem: A 100Ω microstrip line is printed on a substrate of thickness 0.0762 cm, with a dielectric constant of 2.2. Ignoring losses and fringing fields, find the shortest length of this line that appears at its input as a capacitor of 2.5 pF at 2.5 GHz. Repeat for an inductance of 5 nH.

Stripline Most popular type of planer transmission line Geometry of microstrip line

Stripline Phase velocity and the propagation constant of the stripline is given by

Stripline

Stripline Design Step-1: Find√ єr Z0 Step-2: Find the strip width

Stripline Design Step-3: Dielectric attenuation

Stripline Design Attenuation due to conductor loss

Stripline Design Where ‘t’ is the thickness of the strip Rs is the surface resistivity of the conductor and given by

Stripline Design Step-4: Total attenuation constant is given by Step-5: The wavelength on the stripline is Attenuation in term of wavelength

Design Problems Problem-1: Find the width for a 50Ω copper stripline conductor, with b = 0.32cm and єr = 2.20. If the dielectric loss tangent is 0.001 and the operating frequency is 10 GHz, calculate the attenuation in dB/λ. Assume a conductor thickness of t = 0.01mm. Problem-2: Design a stripline transmission line for a 70Ω characteristic impedance. The ground plane separation is 0.316 cm, and the dielectric constant of the filling material is 2.20. What is the guide wavelength on this transmission line if the frequency is 3.0 GHz.

Assignment (due on 22-06-2009) Problem: A microwave antenna feed network operating at 5 GHz a 50 Ω printed transmission line that is 16λ long. Possible choices are (1) copper microstrip, with d = 0.16 cm, єr = 2.20, and tanδ = 0.001, or (2) copper stripline, with b = 0.32 cm, єr = 2.20, and tanδ = 0.001. Which line should be used, if attenuation is to be minimized?

Project-1(due on 06-07-2009) Design a microstrip line (characteristic impedance = 50 Ω, phase shift = 900,substrate FR-4 thickness = 31mil, 61mil, dielectric constant = 4.47, and tangent loss = 0.019) Hand calculations Verify your design using SERENADE HARDWARE implementation Results (hardware )

Instructions Each group has two students. Do your own work. Write project report. No late submission.

Instructions The format for design report should be as follows 1. Title page (including your name, the course number and the date) Your signature after the statement I certify that this design is the result of my own efforts. (Signature) Date: 2. Design objectives and specifications 3. Design steps (including all, mentioned in problem statement) 4. Design modifications, if any 5. Computer design verifications 6. Results (hardware) 7. Conclusions