Hello everyone. I have in mind a project to build home radiotelescope to detect radiopulsars. For this, I need to have a high gain antenna (a least 18 dB) at about 400-430 MHz. Single Yagi with these requirements will be more than 5m long, so I decide to use 4 Yagi with 11 elements (12.3 dB with less than 2m long boom), so the total gain will be about 18.3 dB. A problem, which stops me to build an array antenna is dephasing of individual Yagi in array and degradation of total antennas performance. What I understand, the phasing error is caused by 3 main reasons: 1. Boom mount: the position of Yagi's dipoles are not in a plane 2. Antenna: different impedance cause different responses to the current (signal) phase. Different impedance can be due to errors in positioning antenna elements and the impact of neighborhood objects (trees, buildings, other antennas in the array) 3. Cable length For highly directive individual antennas (like in my case), the effect of dephasing is more strong. When the antenna is at a height lower than 10 wavelength, the effect of ground on the antenna impedance is high. The possible solutions are: 1. Precise assembling of each antenna 2. Install antenna high from the ground and far from obstacles (trees, buildings...) 3. Usage of the dielectric mast, boom... 4. Check each antenna with vector analyzer and fine-tuning of each antenna 5. Simulation of the array in CST or similar software to get the error budget. What I saw at pictures of EME Yagi array, is that people use metallic mast, the mast is not so high. So probably this problem is not so big... I would like to hear the opinion of people, who construct Yagi arrays for EME communication. Did You care about this problem? Did You tune each antenna? What material for mast did You use?