TX antenna - 4SQ-8DIR NEW 8 directions 4SQ antenna

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!FAQ !! '''Phasing of Elements - How it works for 4 + 4 directions''' The conventional antenna fire outward through the corners of the square formed by the four elements, while the modified array can also fire througheach of the four side s. In either case, all the elements are driven by the equalamplitude base currents, but the phase angles are differentresulting in beams heading in various directions. When firing through sides of the square, there are two front elements and two rear elements. There the currents in the front elements lag those of the rear elements by 90°. More in nice article (source): [K3LC design|https://remoteqth.com/img/ZAW-WIKI/4sq-8dir/k3lc.pdf]. !! '''Element Spacing in a 4-Square ''' You do not have to use exactly 0,25 lambda. Please have a look at simulations: [Franz DF6QV|https://remoteqth.com/img/ZAW-WIKI/4sq-8dir/4sq.pdf] !! '''System impedances - Elements + Transformation Lines''' For a good match the four outputs of the system '''must be terminated with 100 Ohms'''. The radiators are connected to them via 75Ω-λ/4-lines transforming the''' 50 Ohm-feed-impedance of the radiators to the required 100 Ohms'''. If the feed-impedance of the radiator is '''different from 50 Ohms, it must be transformed to 50 ± j0 Ohms for an optimal match'''. The λ/4-lines should be made from coaxial cable with a velocity factor ≥ 0.7, otherwise a radiator distance of λ/4 cannot be obtained. *''' For elevated radial elements you can obtain 50 Ohm feed impedance and use 75 Ohms coax for Transformation Lines''' *''' For ground mounted elemets with great ground system the impedance is around 36 Ohms. There 60 Ohms coax cable should be used for Transformation Lines or tune impedance to 50 Ohms in feed point. ''' !!''' Transformation Line calculation lambda / 4 ''' [https://remoteqth.com/img/ZAW-WIKI/4sq-8dir/calc_TL.png|noborder] * '''This hybrid is designed for 100 Ohm from transformation line.''' * When you use 50 Ohms in feed point of vertical, than you should have 100 Ohms at the end of 75 Ohm TL. * When you use 36 Ohms in feed points (ideal vertical on great ground system) you will have around 150 Ohms! '''What means that imput SWR of hybrid and dumped power will be higher!''' !!''' Setup notes by Franz DF6QV ''' Put the box in the center of the planned 4-square and lay the phase lines out in the desired directions. Keep them at an angle of 90 degrees to each other. If using PE insulated lines the positions of the radiators are fixed by their ends, but then the spacing is not quite λ/4. With foam-insulated lines the positions of the radiators have to be chosen at a distance of 0,175 λ (0.25 λ / 1.41) from the center for a λ/4-spacing. Before connecting the radiator to the transformation lines each radiator has to be checked for resonance on the operating frequency with a suitable analyzer. Important: all other radiators are not connected to their feed-lines! After connecting the feed-lines you can measure the transformed feed-point impedance of the antenna at their ends in the center of the 4-square.'''It should be about 100 Ohms. Values between 90 and 110 Ohms are acceptable. '''To check the display on the remote control box, remove all λ/4-lines from the phasing-box; only the built-in dummy load is effective. As the output ports are open, the input power is totally reflected into the dummy load. You can check this by sending 100 watts. The instrument should then read about 0 dB. The SWR remains low in this test!
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