Note: The dBi scale is logarithmic in base 10, where +3 dBi is a doubling in gain! An increase in gain of +1 dBi is equivalent to an increase of 26% and +2 dBi is equivalent to an increase of 60%. Hereis listed currently available instructions, simulated with computer software, for handmade 13-14dBi Double BiQuad external antenna. However I highly recommend to follow my instructions, which are based on computer antenna simulation software 4nec2, to maximize performance. Hence here is the Double BiQuad Antenna and BiQuad Antenna calculators for handmade antenna based on average data. You can make quite a big margin of error in the construction and still get 10-11dBi gain. IntroductionThe BiQuad antenna is fairly easy to build and provides reliable gain and it has very forgiving design. But that's the dominant quality of antenna discussions – based on not-really-understood measures and vague heuristics rather than actual simulation and understanding :(Marcus Müller Marcus MüllerĢ52k 11 11 gold badges 193 193 silver badges 447 447 bronze badges $endgroup$ Not the answer you're looking for? Browse other questions tagged wirelessantenna or ask your own question. The problem I often encounter when researching this kind of question is that many Antenna 'theory' on the internet is written by Hams that assume that SWR (standing wave ratio) is the final and best and only measure for antenna quality, totally ignoring that an impedance-matched terminator has perfect SWR so for example, I found one source that claimed that a driven element-plane distance that would lead to destructive interference is the optimal configuration – probably just because he saw a better impedance matching that way. I'd recommend simulating this stuff – OpenEMS, free as it is, already comes with a Biquad example, and you'd only need to add a reflector to that and play with the parameters. The bent 'legs' might have the purpose of electrically 'enlarging' the plane area, but they might also serve as mechanical improvements, making the ground plane more rigid. You don't get that, but something around two times the quad side length in each direction around the driven element should do most of the work – you don't lose that much if you don't have that. You want an infinitely sized, perfectly conducting ground plane. The metal plane really just has the purpose of acting as a reflector – due to symmetry, the biquad has the same pattern into the 'front' and back, and adding a simple metal plane in the right distance from the antenna will make the reflections add up constructively with the 'forward' direction, thus adding a 3dB to gain (in theory). Lanse7pty lanse7pty $endgroup$ 2 Answers $begingroup$
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