I made 4-legged Spider only once, and that also long ago. I mostly made 8-legged ones (Quick Spider). Frankly speaking I never thought of, and never tested, the effect of rotating the Spider horizontally. However logically more legs should minimize the variation in reception with horizontal rotation of the Spider.
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Thanks for the reply.
That’s what I thought, too. I will add more legs to see if there is an improvement.
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Why not go for the ‘infinite legs’?
By that, I mean make a cone out Al-foil, a one-use baking tray etc.
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There is one issue with this solution (I have tried it with my first spider), you have to be very precise and gentle with trimming the edges of the cone so to keep the length close to 68mm. It’s very difficult to work with alum foil, being very fragile, but I may try it again this time using aluminum plates that are much more rigid.
not so hard - use four layers. Don’t cut the edges, just fold them over.
If the “legs” were vertical, the antenna wouls be a di-pole
If the “legs” were horizontal, the antenna would be a ground plane
Adjusting the angle alters the feed impedance.
Similarly, if it’s a di-pole, the length wants to be 1/4 lambda, but if it’s a ground plane, then it “should” be infinite.
From these two boundary conditions, it’s easy to see that the 1/4 lambda length becomes less relevent the further from a di-pole and the closer to a ground plane the antenna becomes.
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Thanks for the explanation. From what I understand, this antenna is somewhere between a dipole and a ground plane, so being very scholastic with the foil length isn’t of much importance.
Pretty well, yes.
There is a bit of voodoo in the maths where one effect becomes dominent over another.