matching techniques and baluns l.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
Matching Techniques and Baluns PowerPoint Presentation
Download Presentation
Matching Techniques and Baluns

Loading in 2 Seconds...

play fullscreen
1 / 19

Matching Techniques and Baluns - PowerPoint PPT Presentation


  • 130 Views
  • Uploaded on

Matching Techniques and Baluns. INEL 5305 Dr. Sandra Cruz-Pol ECE, UPRM. Ref. Balanis sect. 9.8, 14.8. Matching Techniques. Matching over the desired frequency range when connecting the T.L. to the antenna Types Stub-matching l /4 transformer: single or multiple. Z o (real).

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Matching Techniques and Baluns' - zeke


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
matching techniques and baluns

Matching Techniquesand Baluns

INEL 5305

Dr. Sandra Cruz-Pol

ECE, UPRM

Ref. Balanis sect. 9.8, 14.8

matching techniques
Matching Techniques
  • Matching over the desired frequency range

when connecting the T.L. to the antenna

  • Types
    • Stub-matching
    • l/4 transformer: single or multiple

Zo(real)

ZL(complex)

l 4 transformer matching single section
l/4 transformer-matching: Single Section
  • First move so that ZL is completely real

l/4

so

Zo

Zx

l 4 transformer matching multiple section provides broader bw

l/4

l/4

l/4

l/4

Zo

so

l/4 transformer-matching: Multiple- Section- provides broader BW
  • First move so that ZL is completely real

Could be designed using Dolph-Tchevy or Taylor coefficients.

multiple sections quarter wave xmer
Multiple sections: Quarter-wave Xmer
  • N-sections
  • Can be implemented several ways
    • Binomial
    • Tschebyscheff
multiple sections quarter wave xmer7
Multiple sections: Quarter-wave Xmer
  • For symmetrical Xmer,
  • Binomial Coefficients

n=0,1,2,…N

binomial design for multiple sections quarter wave xmer
Binomial Design for Multiple sections Quarter-wave Xmer
  • Fractional Bandwidth:

where rm= maximum value of reflection coefficient which can be tolerated within the bandwidth.

Use Radians!!!

design

implementing with microstrip
Implementing with Microstrip
  • For Microstrip lines:
comparison of frequency response for matching quarter wave network

Binomial

(Maximally flat)

Tschebyscheff

Comparison of frequency response for matching quarter-wave network

0.5 1.0 1.5

matching techniques12
Matching-techniques
  • There are other techniques for matching a line to the antenna;
    • T-Match
    • Gamma Match
    • Baluns
baluns
Baluns

BALance to UNbalance Converters

  • a passive electronic device that converts between balanced and unbalanced electrical signals, such as between coaxial cable and dipole antenna.
    • Present in some radars, transmitters, satellites, in every telephone network, and probably in most wireless network modem/routers used in homes.
  • A 75- to 300 ohm balun:
baluns current distribution

Balun

Coaxial Line

(unbalanced)

Baluns- current distribution

Current

distribution

Coaxial Line

(unbalanced)

Current

leak

|| wire transmission line

(balanced)

Balanced load

Some antennas like the monopole or horn are unbalance loads, and it’s ok to use a coaxial cable to feed them.

balanced source
Balanced source
  • The source is balanced if the voltage potential of one level is equally above ground as the other is below ground at all instants of time.
    • Example: +50V and -50V is balanced, +30V and +12V or +20V and 0V are NOT balanced.
some types of baluns
Some types of baluns

Ferrite Core

(toroidal)

l/4 coax

Bazooka

l/2 coax

l/4 above looks like an open circuit, therefore the leak current is zero.

l/4 above looks like an open circuit, therefore the leak current is zero.

Shorted to coaxial outer conductor

Shorted to coaxial outer conductor

slide17

Transforms Z, 4:1 or 1:4

  • Increased bandwidth but may not behave well at very hi frequencies. There are losses in iron core. Can be made 1:1 or impedance transforming such as 4:1
feed networks for arrays
Feed Networks for Arrays
  • Series feed
  • Parallel

(Corporate)

  • Space feed

Usually one source feeds all elements in the array. Have to be careful not to affect the amplitude and phase of the feed to each element. Also the mutual impedance of neighboring elements.

corporate feed
Corporate Feed

a) Tapered lines

b) quarter-wave Xmers