is this 'flare angle' term correct? another bicone thread - Page 1
Forum section: electronics / rf-microwave

author: coppercone2
author_rank: Super Contributor
timestamp: October 20, 2019, 04:17:31 am
content: https://www.researchgate.net/publication/238594497_Direct_feed_biconical_antenna_as_a_reference_antennaThis paper claims the flare angle is the half angle between the two cones. I happened to build my cone at 65 degrees according to the paper. My measurement for A is 12 inches and for theta is ~65 degrees.In the paper the figure 5(A) shows a pancake, basically if you defined flare angle differently. is this just a horrible resize? It does not appear to match figure 2 if you consider the flare angle to be 65 degrees as defined by figure 2. That picture of the prototype looks like the flare angle is like 30 degrees! my antenna looks like figure 1 A. Which I would assume has a flare angle of around 60 degrees.I don't even wanna try to reverse engineer something from his dimensions because it looks so suspicious... is that just a horrible resize? Am I missing something about flare angle?And, can anyone actually read the formula provided? By the time he gets to beta over alpha it looks illegible.I don't know what kind of arcane tomes I would need to try to evaluate the equation, but it would help if I could actually.. read itit looks pretty well defined in figure 2........ so what the fuck is with figure 5. did someone sit on the thing?Never mind, I need to read better. its a direct feed. I thought it was fed from the side. God damnit. So my flare angle is 30 degrees.at least it looks goodthe correct one looks ridiclous

author: hagster
author_rank: Frequent Contributor
timestamp: October 20, 2019, 05:51:51 am
content: Looks like you found your answer. The flare angle is defined from the centre axis of the cones. So zero flare would be a dipole and 90° flare would be parallel discs.

author: coppercone2
author_rank: Super Contributor
timestamp: October 20, 2019, 06:00:29 am
content: the diagram it just confusing unless you read the caption or notice the 1mm spacing on your screen since the first picture it shows is the air raid siren style.i probobly built it wrong in the first place because of that years ago, they should shade it with a grid IMO

author: coppercone2
author_rank: Super Contributor
timestamp: October 20, 2019, 07:35:17 pm
content: ok, the connector seems messed up and needs a bit of work, but it appears this antenna is centered ~150MHz with a dip from the reflection. the bandwidth dances around, no doubt either the connector is filthy or the solder joint popped from all the abrasive action from die grinder, dremel and polishing tool.Need to remove a little dielectric spacer to inspect but first I will let it soak in deoxit for a day and flush it with strong contact cleaner and do inspection.I highly do not recommend making the ones that have the connector inside of the cone. its too much a bastard to repair if you put a little collar around it (glued).

author: coppercone2
author_rank: Super Contributor
timestamp: October 20, 2019, 11:43:18 pm
content: here is the reflection pattern measured by a DC and VNA that does not have proper things. its not really calibrated or anything but this is how it might turn out. also its a severe impedance mismatch and it needs a matching network so its not really useful data, I was just curious.it can detect if people are walking down stairs using VNA too because the Q changes

author: 9aplus
author_rank: Regular Contributor
timestamp: October 22, 2019, 12:12:27 pm
content: @Copperconehttps://hackaday.io/project/28119-biconical-dipole-antenna-ikea-conesJust FYI, made this one with N connector while ago.One day may repeat the exercise with SMA , have one unused spare set