UHF Array Element Using a Reflection Coefficient Modulator
A 432 MHz array element is described using a compact 4 element Yagi, quarter wavelength transmission line, and diode reflection coefficient modulator. Measurements in the anechoic chamber show an array element gain of 10.5 dBi. PN junction, Schottky barrier, and PIN diodes are compared using a common -3.8 dBm 700 Hz sine wave modulation source. The low-barrier microwave Schottky diodes are only 1.4 dB better than common 1N4152 PN diodes at 432 MHz. E and H pattern and gain measurements using the Yagi as a modulated scatterer element are compared with E and H far-field simulations. As expected, gain is higher as a transponder element than the 9.1 dBi Yagi gain predicted in far-field pattern simulations. This element will be used in modulated scatterer signal processing arrays.