grocket

I have been working on feeding my helical from the center of the coil and using a rectangle impedance matching stub. I am not sure how to account for the length leading to the center feed (1/2 radius of coil). Example: 3 turn helical + coil radius feed= Frequency change? Also, do I use the same impedance matching stub size when feeding from the center? I hope I explained myself correctly. Thank you.

Thank you!

BTW, the distance between coils..from the outer edge of the coils, right? Not the centers..

Fantastic..I will give it a go. Thank you so much for actually replying and fast! In your above example using tape rather than wire...I would like to use tape rather than wire, what design adjustment will I need to make. For example I used 2mm wire on the 2.4...6mm tape ok?

Thank you. I will have to get this on my older PC, as I currently use a Mac. I would like to try a 1x2 array with the 3 turn I am using shown above. What distance would I use? or what equation will determine the minimum distance between coils (multiples of wavelength)? Reflectors to edge sounds too easy. I also applied this to a 3 turn at 5.8 ghz.

That is the research I used to construct them. Used fusion 360 design and print in ABS. Unfortunately, it does not address design parameters...just concepts. I would like to apply it to other frequencies, but it would be impossible to experimentally determine parasitic disk size/distance. I do not have test equipment or simulation software. Is there any free online simulation software available similar to what you used above? Looks expensive. Thank you for the help.

Yes, went through a few iterations on the 3d print/construction. Just dialed (range tested on ground and in air) them in last week. 11.3 deg on the coil. In practice the disk really seems to punch the signal through...no drop outs.

I am new to this forum. Impressive work here. I love it. I would love to try this one..where could I get the dimensions/original research? That coil spacing/angle is impressive. I have used the parasitic disk concept successfully as seen in the pics. 3d printed construction for accuracy. Inset wire grove and parasitic standoff. They are much more compact. I use them on my 2.4 ghz RC transmitter with cp biquad on the receiving end. Massively improved range, but more importantly no dropouts or fly-aways.