Helix Antenne impedance matching at 433Mhz ?
We have tried to make an Helix antenna on 70 centimetres wavelength 433Mhz. we have looked at some design rules at 23, 13, WLAN Helix antenna design and have seen that the matching can be done by 1/4 wavelength coax cable or 1/4 wavelength stripline. but how do we calculate the distances from the ground plane and the wide, size, shape ?
Mads & Ivan
What's your motivation not to go for a simple rod (monopole) antenna? Which helix antenna mode to you want to utilize? A helical antenna in normal (or "broadside") mode is sometimes used either as shortened (< λ/4) monopole or as a monpole with increased horizontal directivity. Axial or "end-fire" mode in contrast acts as a circular polarized antenna with directivity, but needs several λ length.
we use Axial mode. we Will like to do some antenna bearing that, why we use Helix antenna . our diameter is 21cm and our spacing is 1/4 wavelength about 17,3 cm and we don't know if the number of turns is increase the impedance and how we know the impedance of Helix Coil. we have about 8 to 10 turns over 6meter copper tube 1cm i diameter.... the guide say some thing 137 ohm impedance to there design. but not how they calculate it.
Formulas for axial mode helix antenna can be found in Balanis, Antenna Theory (3rd edition).
Kraus discusses the design of a helix. I have always found this to be a useful reference.
thanks for the book title