Subscribe To This Site
Add to Google
Add to My Yahoo!
Add to My MSN
Subscribe with Bloglines

AC Current
AC Motors
AC Generators
Antenna Principles
Basic Electronics
Blog it!
Circuit Control
Circuit Measuring
Cable Connectors
DC Current
DC Motors
Electron Tubes
Our Visitor's
Power Supplies
Project Videos
Radio Waves
Special Logic
Specialty Tubes
Spectrum Analyzer
Tubes Cont. -
Transmission Lines
Trans. Lines Cont.-
Tuned Circuits
Wave Propagation
Wiring Techniques


Rectangular-Coordinate Pattern

Look at view A of the figure below. The numbered positions around the circle are laid out on the HORIZONTAL AXIS of the graph from 0 to 7 units. The measured radiation is laid out on the VERTICAL AXIS of the graph from 0 to 10 units. The units on both axes are chosen so the pattern occupies a convenient part of the graph.

The horizontal and vertical axes are at a right angle to each other. The point where the axes cross each other is known as the ORIGIN. In this case, the origin is 0 on both axes. Now, assume that a radiation value of 7 units view B is measured at position 2. From position 2 on the horizontal axis, a dotted line is projected upwards that runs parallel to the vertical axis. From position 7 on the vertical axis, a line is projected to the right that runs parallel to the horizontal axis. The point where the two lines cross (INTERCEPT) represents a value of 7 radiation units at position 2. This is the only point on the graph that can represent this value.

As you can see from the figure, the lines used to plot the point form a rectangle. For this reason, this type of plot is called a rectangular-coordinate graph. A new rectangle is formed for each different point plotted. In this example, the points plotted lie in a straight line extending from 7 units on the vertical scale to the projection of position 7 on the horizontal scale. This is the characteristic pattern in rectangular coordinates of an isotropic source of radiation.

Comparison of rectangular- and polar-coordinate graphs for an isotropic source

Polar-Coordinate Pattern

The polar-coordinate graph has proved to be of great use in studying radiation patterns. Compare views A and B of the figure above. Note the great difference in the shape of the radiation pattern when it is transferred from the rectangular-coordinate graph in view A to the polar-coordinate graph in view B. The scale of radiation values used in both graphs is identical, and the measurements taken are both the same. However, the shape of the pattern is drastically different.

Look at view B of the figure above and assume that the center of the concentric circles is the Sun. Assume that a radius is drawn from the Sun (center of the circle) to position 0 of the circle. When you move to position 1, the radius moves to position 1; when you move to position 2, the radius also moves to position 2, and so on.

The positions where a measurement was taken are marked as 0 through 7 on the graph. Note how the position of the radius indicates the actual direction from the source at which the measurement was taken. This is a distinct advantage over the rectangular-coordinate graph in which the position is indicated along a straight-line axis and has no physical relation to the actual direction of measurement. Now that we have a way to indicate the direction of measurement, we must devise a way to indicate the magnitude of the radiation.

Notice that the rotating axis is always drawn from the center of the graph to some position on the edge of the graph. As the axis moves toward the edge of the graph, it passes through a set of equally-spaced, concentric circles. In this example view B, they are numbered successively from 1 to 10 from the center out. These circles are used to indicate the magnitude of the radiation.

The advantages of the polar-coordinate graph are immediately evident. The source, which is at the center of the observation circles, is also at the center of the graph. By looking at a polar-coordinate plot of a radiation pattern, you can immediately see the direction and strength of radiation put out by the source. Therefore, the polar-coordinate graph is more useful than the rectangular-coordinate graph in plotting radiation patterns.

(back) (top) (next)

Subscribe to this site!

Enter your E-mail Address
Enter your First Name (optional)

Don't worry -- your e-mail address is totally secure.
I promise to use it only to send you Learn-about-electronics.

SiteSearch Google

Can't find what you are looking for? Enter your search here.

Custom Search

Translate your page

If English is not your first language you can Translate the text on this page to any one of the languages found in the drop down menu. Select your language from the list for an instant translation.

Find it on Amazon

Looking for something unique? Try our Amazon search engine.

Our Visitors

Find out what our visitors think. Add your own words and get featured. Just click on the link.

Lacy from Florida Writes... This site is amazing, it's great to see a site where it is all right there in plain English, clear and understandable. Thank you for your help

Lisa, from anytown USA, writes... OMG! Your site helped me with my science report on Covalent Bonding, thank you so much. Rocking Site man.

Online Reference
Dictionary, Encyclopedia & more
Look in: Dictionary & thesaurus
Medical Dictionary
Legal Dictionary
Financial Dictionary
Other languages:

Around the World!

Click on the Clustrmaps map to see where this site has been helping people learn about electronics in the last 24 hours.

Locations of visitors to this page

You are the

joomla analytics
unique visitor to this site.