Microstrip Patch Antennas EEE 212 EEE 212 MICROSTIP

Microstrip Patch Antennas EEE 212

EEE 212 MICROSTIP LINES

1952

Transmission Lines in ADS • Only the top conductor is shown in ADS – like you are looking at the circuit from the above • Ground plane is normally not shown • Example

Ideal Transmission Lines in ADS Pulldown menu: Tlines-Ideal

Ideal Transmission Lines in ADS Pulldown menu: Tlines-Ideal

Ideal Line S-parameters in ADS

Ideal Line S-parameters in ADS

Open/Shorted Transmission Line (Stub)

Open Transmission Line in parallel with the main line

Quiz: Shorted transmission line in parallel with the main line

Open Transmission Line in parallel with the main line

Microstrip Lines in ADS Pulldown menu: Tlines-Microstrip The length of the line L -> electrical length E of ideal line The width of the line W -> impedance Z of ideal line

How do we calculate width and length of the microstrip line if we know Z, E? And vice versa? • Use Line Calc in ADS • Use equations and write a matlab code

Use Line Calc From Schematic Diagram in ADS Tools-> Line Calc -> Start Line Calc

Quiz: Use Line Calc to find w and l of a microstrip line on RT/Duroid 6002 at 1 GHz. Zo=100 Ohms, l=90 degrees

Lossless Microstrip Line Phase velocity in dielectric: Phase velocity for microstrip: Quasi-TEM

Microstrip (cont. )

Microstrip (cont. ) Inverse process: Given Z 0, find w The solution formulas are based on two numerical fits, defined in terms of the value of Z 0 relative to that of the effective permittivity.

Intro to microwave substrates

EEE 212 QUARTER WAVE TRANSFORMER IMPEDANCE MATCHING

Examples of Matching Networks

Reflection Coefficient

Example

Example

Reflection Coefficient on the Smith Ch

Reflection Coefficient on the Smith Ch

Reading input impedance using Wavelength Toward Generator scale 1. Find the load impedance on SC 2. Draw an SWR circle 3. Draw a line from the center of the SC to the edge to find the reference position on the scale wavelengths toward generator. 4. We add the transmission line length to the reference position 5. We find the position of Zin on the wavelength toward generator scale 6. Draw a line from the center of the circle to the edge of the Smith Chart 7. Where the SWR circle crosses the line ->Zin

Example – Find the input impedance

Example – Find the input impedance

Quarter Wave Transformer

ANTENNA DESIGNER’S CONCERNS

http: //books. google. com/books/about/Handbook_of_Microstrip_Antennas. html? id=Nh. Nk 04 g. Wh 7 AC

http: //books. google. com/books/about/Handbook_of_Microstrip_Antennas. html? id=Nh. Nk 04 g. Wh 7 AC

EEE 212 MICROSTRIP PATCH ANTENNA

http: //books. google. com/books/about/Handbook_of_Microstrip_Antennas. html? id=Nh. Nk 04 g. Wh 7 AC

History • Radiation effects reported by Grieg and Engelmann (50 s) • Deschamps – an array of triangular antennas (50 s) • 70 s new generation of missiles required antennas conforming to the missile surface • In 80 s substrate manufacturing improved – intense R&D focused on patch

Patch Antenna

http: //books. google. com/books/about/Handbook_of_Microstrip_Antennas. html? id=Nh. Nk 04 g. Wh 7 AC

http: //books. google. com/books/about/Handbook_of_Microstrip_Antennas. html? id=Nh. Nk 04 g. Wh 7 AC

EEE 212 FEED

Coax and Strip Line Patch Feeding

Electromagnetic Coupling Feed

Aperture-Fed Patch

Capacitive Coupled Feed

Inset-Fed Patch

EEE 212 REDUCED SIZE PATCH

Quarter-Wave Patch

Adding a Shorting Pin

Meandering Current Paths

Folding Microstrip Patches

Dual Patch Structure

Patch Antenna Array Feeds

Series Feed Array

EEE 212 PATCH MODELING

Patch Modeling Methods • • Cavity Model Analytical Transmission Line Model Multiple Network Model (MNM) Method of Moments (Mo. M) Numerical Finite-Element Model (FEM) Spectral Domain Technique (SDT) Finite-Difference Time Domain (FTDT)

Transmission-line Model • Patch modeled as a section of transmission line • The field varies only along the length (No variation of transverse field ) • Open circuit at the and of the resonator is modeled with equivalent admittance • Easiest and lowest accuracy model

Microstrip Line

Effective Dielectric Constant

Equation for Length Extension

Frequency of Dominant Mode

Patch Width

Patch Design Process

Equivalent Model

Slot Admittance

Inset Feed

Input resistance for the inset feed

Input Resistance Seen by Coax