That's an interesting question. One way to incorporate the concept of an isotropic antenna with randomness or unpredictability on a website could be to use a visual representation of the antenna emitting signals in all directions. You could use a 3D model of the antenna and animate it to show the signals radiating outwards in a random pattern.
Another idea could be to use a particle system to simulate the radiation pattern of the antenna. You could use a random seed to generate a unique pattern each time the page is loaded, creating a sense of unpredictability.
To incorporate user interaction, you could allow users to manipulate the antenna's orientation and see how it affects the radiation pattern. You could also allow users to adjust the frequency or wavelength of the signals being emitted, which would affect the pattern as well.
Overall, the key to designing an effective interactive element that represents both concepts is to find a balance between visual appeal and functionality. The element should be visually engaging and intuitive to use, while also accurately conveying the concepts you want to communicate.