Broadband Dual-Use Array with Planar Log Periodic Dipole Elements

This paper presents a phased array consisting of 8 horizontally positioned planar log periodic dipole array antennas for use over the frequency range of 800 to 1,300 MHz. The array is dual use in that it can either scan in azimuth with a narrow beam or be forward looking with a null-filled broad beam. To achieve the broad beam, the 8-element array is divided into two 4-element subarrays. The main beam of each subarray is then pointed near the first null of the 8-element uniform array radiation pattern to “fill” the nulls. The results for the narrow beam configuration produce an azimuthal beamwidth of 15° with 15 dBi of gain, and the null- filled configuration produces an increase in azimuthal beamwidth to 55° (40° increase) with a peak gain of 10 dBi (loss of 5 dB). Note that this paper only presents the antenna development and array testing but not any system hardware.