Microstrip log-periodic antenna array with endfire beam

Endfire action with a very wide-bandwidth, low-profile antenna array has not yet been achieved. After showing that a conventional microstrip log-periodic array cannot be successfully scanned from broadside to endfire, a new configuration involving quarter-wavelength shorted patches is described. First-order theory indicates that good endfire action should be possible, and this is confirmed by preliminary measurements on an array designed for a 25% bandwidth. Radiation pattern control is seen to be the most critical performance parameter.