Quantcast TERMINATING A TRANSMISSION LINE

Share on Google+Share on FacebookShare on LinkedInShare on TwitterShare on DiggShare on Stumble Upon
Custom Search
 
  
 
3-38 Q24.   In figure 3-27, which waveforms on the left have a resultant wave of zero, and what is indicated by these waves? Q25.   On an open-ended transmission line, the voltage is always zero at what distance from each end of the line? TERMINATING A TRANSMISSION LINE A transmission line is either NONRESONANT or RESONANT. First, let us define the terms nonresonant lines and resonant lines. A nonresonant line is a line that has no standing waves of current and voltage. A resonant line is a line that has standing waves of current and voltage. Nonresonant Lines A nonresonant line is either infinitely long or terminated in its characteristic impedance. Since no reflections occur, all the energy traveling down the line is absorbed by the load which terminates the line. Since no standing waves are present, this type of line is sometimes spoken of as a FLAT line. In addition, because the load impedance of such a line is equal to Z0, no special tuning devices are required to effect a maximum power transfer; hence, the line is also called an UNTUNED line. Resonant Lines A resonant line has a finite length and is not terminated in its characteristic impedance. Therefore reflections of energy do occur. The load impedance is different from the Z0 of the line; therefore, the input impedance may not be purely resistive but may have reactive components. Tuning devices are used to eliminate the reactance and to bring about maximum power transfer from the source to the line. Therefore, a resonant line is sometimes called a TUNED line. The line also may be used for a resonant or tuned circuit. A resonant line is sometimes said to be resonant at an applied frequency. This means that at one frequency the line acts as a resonant circuit. It may act either as a high-resistive circuit (parallel resonant) or as a low-resistive circuit (series resonant). The line may be made to act in this manner by either open- or short-circuiting it at the output end and cutting it to some multiple of a quarter-wavelength. At the points of voltage maxima and minima on a short-circuited or open-circuited line, the line impedance is resistive. On a short-circuited line, each point at an odd number of quarter-wavelengths from the receiving end has a high impedance (figure 3-31, view A). If the frequency of the applied voltage to the line is varied, this impedance decreases as the effective length of the line changes. This variation is exactly the same as the change in the impedance of a parallel-resonant circuit when the applied frequency is varied.


Electrical News
Metaio Brings Augmented Reality to the Smartwatch
Leading augmented reality software developer, Metaio, is bringing its visual...
eetimes.com
Google Glass Goes to the Opera
Italy's Teatro Lirico di Cagliar will become the first in...
eetimes.com
EEVblog #646 – Gravity Detection Using A Frequency Counter!
Did you know you can use your frequency counter to...
eevblog.com
Creating an 8x8x8 3D LED Cube: Testing the RGB LEDs
Creating an 8x8x8 3D tri-color LED cube from the ground...
eetimes.com
Massive Job Cuts: Dark Clouds Over Lighting Business
Amid the decline of conventional illuminants like incandescent bulbs and...
eetimes.com
Next-Gen HiFi Competition Takes Place in the Car
Car radio? Old school. Infotainment? Better. Now the next generation...
eetimes.com
No More Dialup: Grandpa Gets DSL
We all talk about needing multi-megabit-per-second home Internet, but not...
eetimes.com
Ushering in Big-Data & Giga-Scale Design Challenges
Giga-scale designs are moving from traditional FastSPICE applications to new...
eetimes.com
Kid-Friendly Science Museums We Love
In summer, parents find themselves groping for the perfect spot...
eetimes.com
Pi in the Sky Over New York
Residents of the five boroughs (and even that far away...
eetimes.com
Tesla Gets Its First Android Wear Smartwatch App
The car of the future, Tesla, just got even cooler...
eetimes.com
IBM Breaks EUV Throughput Record
An ASML NXE3300B extreme ultraviolet scanner exposed 637 wafers in...
eetimes.com
Fist Bumps & the Zombie Apocalypse
A fist bump transmits about 1/20th of the pathogens as...
eetimes.com
Google Opens Google Glass Basecamps
Google has set up three basecamps to help long-term Explorers,...
eetimes.com
25G Ethernet Looks Back to Future
The chairman of the group that set 40 and 100...
eetimes.com
Introducing FPGA-Based Acceleration for High-Frequency Trading
Handling market data is of highest merit and demands the...
eetimes.com
GM's Powermat Deal Falls Short
General Motors recently announced that it will include multimode wireless...
eetimes.com
Repurposing an FM Radio Chip for an RC Submarine Receiver Project
Adam is currently working on a 75MHz receiver for his...
eetimes.com
IoT Spec Taps Internet Protocol
The IPSO Alliance will release a reference architecture for an...
eetimes.com
Micron Makes Monolithic 8GB DDR3
Using a 25 nm manufacturing process, Micron has created a...
eetimes.com
 


Privacy Statement - Copyright Information. - Contact Us

comments powered by Disqus

Integrated Publishing, Inc.
9438 US Hwy 19N #311 Port Richey, FL 34668

Phone For Parts Inquiries: (727) 755-3260
Google +