SOURCE

<div class="radar"></div>

<div style="text-align:center;margin:50px 0; font:normal 14px/24px 'MicroSoft YaHei';color:#ffffff">

* {
  box-sizing: border-box;
}

html {
  height: 100%;
  background-color: #111;
  font-size: 10px;
}

body {
  background-image: linear-gradient(0deg, transparent 24%, rgba(32, 255, 77, 0.15) 25%, rgba(32, 255, 77, 0.15) 26%, transparent 27%, transparent 74%, rgba(32, 255, 77, 0.15) 75%, rgba(32, 255, 77, 0.15) 76%, transparent 77%, transparent), linear-gradient(90deg, transparent 24%, rgba(32, 255, 77, 0.15) 25%, rgba(32, 255, 77, 0.15) 26%, transparent 27%, transparent 74%, rgba(32, 255, 77, 0.15) 75%, rgba(32, 255, 77, 0.15) 76%, transparent 77%, transparent);
  background-size: 7rem 7rem;
  background-position: -5.2rem -5.2rem;
  width: 100%;
  height: 100%;
  position: relative;
  padding: 0;
  margin: 0;
  font-size: 1.6rem;
}

.radar {
  background: -webkit-radial-gradient(center, rgba(32, 255, 77, 0.3) 0%, rgba(32, 255, 77, 0) 75%), -webkit-repeating-radial-gradient(rgba(32, 255, 77, 0) 5.8%, rgba(32, 255, 77, 0) 18%, #20ff4d 18.6%, rgba(32, 255, 77, 0) 18.9%), -webkit-linear-gradient(90deg, rgba(32, 255, 77, 0) 49.5%, #20ff4d 50%, #20ff4d 50%, rgba(32, 255, 77, 0) 50.2%), -webkit-linear-gradient(0deg, rgba(32, 255, 77, 0) 49.5%, #20ff4d 50%, #20ff4d 50%, rgba(32, 255, 77, 0) 50.2%);
  background: radial-gradient(center, rgba(32, 255, 77, 0.3) 0%, rgba(32, 255, 77, 0) 75%), repeating-radial-gradient(rgba(32, 255, 77, 0) 5.8%, rgba(32, 255, 77, 0) 18%, #20ff4d 18.6%, rgba(32, 255, 77, 0) 18.9%), linear-gradient(90deg, rgba(32, 255, 77, 0) 49.5%, #20ff4d 50%, #20ff4d 50%, rgba(32, 255, 77, 0) 50.2%), linear-gradient(0deg, rgba(32, 255, 77, 0) 49.5%, #20ff4d 50%, #20ff4d 50%, rgba(32, 255, 77, 0) 50.2%);
  width: 75vw;
  height: 75vw;
  max-height: 75vh;
  max-width: 75vh;
  position: relative;
  left: 50%;
  top: 50%;
  transform: translate(-50%, -50%);
  border-radius: 50%;
  border: 0.2rem solid #20ff4d;
  overflow: hidden;
}
.radar:before {
  content: ' ';
  display: block;
  position: absolute;
  width: 100%;
  height: 100%;
  border-radius: 50%;
  animation: blips 5s infinite;
  animation-timing-function: linear;
  animation-delay: 1.4s;
}
.radar:after {
  content: ' ';
  display: block;
  background-image: linear-gradient(44deg, rgba(0, 255, 51, 0) 50%, #00ff33 100%);
  width: 50%;
  height: 50%;
  position: absolute;
  top: 0;
  left: 0;
  animation: radar-beam 5s infinite;
  animation-timing-function: linear;
  transform-origin: bottom right;
  border-radius: 100% 0 0 0;
}

@keyframes radar-beam {
  0% {
    transform: rotate(0deg);
  }
  100% {
    transform: rotate(360deg);
  }
}
@keyframes blips {
  14% {
    background: radial-gradient(2vmin circle at 75% 70%, #ffffff 10%, #20ff4d 30%, rgba(255, 255, 255, 0) 100%);
  }
  14.0002% {
    background: radial-gradient(2vmin circle at 75% 70%, #ffffff 10%, #20ff4d 30%, rgba(255, 255, 255, 0) 100%), radial-gradient(2vmin circle at 63% 72%, #ffffff 10%, #20ff4d 30%, rgba(255, 255, 255, 0) 100%);
  }
  25% {
    background: radial-gradient(2vmin circle at 75% 70%, #ffffff 10%, #20ff4d 30%, rgba(255, 255, 255, 0) 100%), radial-gradient(2vmin circle at 63% 72%, #ffffff 10%, #20ff4d 30%, rgba(255, 255, 255, 0) 100%), radial-gradient(2vmin circle at 56% 86%, #ffffff 10%, #20ff4d 30%, rgba(255, 255, 255, 0) 100%);
  }
  26% {
    background: radial-gradient(2vmin circle at 75% 70%, #ffffff 10%, #20ff4d 30%, rgba(255, 255, 255, 0) 100%), radial-gradient(2vmin circle at 63% 72%, #ffffff 10%, #20ff4d 30%, rgba(255, 255, 255, 0) 100%), radial-gradient(2vmin circle at 56% 86%, #ffffff 10%, #20ff4d 30%, rgba(255, 255, 255, 0) 100%);
    opacity: 1;
  }
  100% {
    background: radial-gradient(2vmin circle at 75% 70%, #ffffff 10%, #20ff4d 30%, rgba(255, 255, 255, 0) 100%), radial-gradient(2vmin circle at 63% 72%, #ffffff 10%, #20ff4d 30%, rgba(255, 255, 255, 0) 100%), radial-gradient(2vmin circle at 56% 86%, #ffffff 10%, #20ff4d 30%, rgba(255, 255, 255, 0) 100%);
    opacity: 0;
  }
}