Cross-YAGI 3el на SATCOM. Part I (конструктив)

Cross-YAGI 3el in an hour... a budget-friendly mount for split vibrators and directors without a 3D printer. Part I http://raxp2.blogspot.com/2020/08/cro... Support the channel https://donatepay.ru/don/636177 and don't forget to subscribe #LaboratoryW #SATCOM #Zastone #M7 #yagi - - - - - - Get access to unique life hacks and developments by following this link:    / @laboratoryw   The fasteners used are classic screw terminal blocks for indoor use, 1.5-4 square meters, from a nearby lighting store. To protect against external climatic influences, the terminal block housing is coated with Plastik 70 acrylic varnish. However, the design is intended for handheld operation or field use from a tripod. To secure the split vibrators, the first and second internal brass bushings are each split into two halves using a Dremel. The terminal blocks are mounted in pairs on the inside of an 18x18 mm L-shaped aluminum boom for two reasons: the boom wall serves as a stop for the terminal block housing, preventing it from rotating, as it is secured with a single bolt connection, and the terminal block's overall dimensions are concealed within the boom. Circular RHCP polarization is achieved using a phasing section of 50-ohm coaxial cable and a Wilkinson combiner. The equivalent gain of a 3-element cross antenna is -3 dB less than the gain of a 3-element linearly polarized antenna. Since the antenna elements pass through a metal boom in the center, a local increase in the element size in this location is equivalent to a decrease in the linear inductance, i.e., a shortening of the element. Let's estimate the boom correction value in lambda using the empirical formula from DL6WU as K = D * (12.5975 * D - 114.5 * D * D), valid for boom diameters up to 0.05 wavelengths. Let's assume a boom with a circular cross-section of d = 18 mm, which corresponds to D = 0.017 lambda for a transmission frequency of 297 MHz, hence K = 0.003 lambda. That is, the element lengths should be increased by 300 * 0.003 / 297 = 0.003 m = 3 mm. However, the elements used are enameled winding wire, and it is impossible to verify the shortening factor. Therefore, the assembled structure will be tested with a vector antenna analyzer after the fact. To be continued...