Gain patterns can be drawn for microphones, radio antennas and light reflecting from surfaces. They are both informative and beautiful. The following images show the gain of a certain "wideband" herringbone antenna as frequency increases. Gain is simply the sensitivity of the antenna to a signal in a given direction.
When you tune a radio, you are selecting which frequency you want to listen to. But your antenna has to be cooperating by being sensitive to both the frequency of that station, its location, and how the signal bounces off the sky, land, water, trees, mountains and buildings.
So to begin we tune to 1.0 megahertz on our radio dial. In the pictures that follow we will increase the frequency on our radio dial by a factor of ten with each click. That makes for pretty big jumps. I hope to animate the in-between's soon. There are so many variables one must decide what to show first. In the meantime here is a keyframe warm-up starting at the promised 1 MHz. Captions are below the images.
You Say Tomato
1 MHz - Radially symmetric pattern, more gain at top than bottom.
I Say Potato
10 MHz -More gain at the ends than the middle.
The Edges of Lambda
The Edges of Lambda
100 MHz -Nature is more beautiful than I can imagine.
Butterfly Spectacular
1000 MHz -Think about this next time you tune a radio.
The last picture is around the frequency of cellphones and some cordless phones. But their antennas actually have blobby radiation patterns like the first example. Can you think why that might be so?
