Logarithmic Helical Biconical UWB Antenna

grabcad

This is a model of a Logarithmic (Log) Helical Biconical Ultra WideBand (UWB) Antenna that is based upon a 3D printed form that i created. It uses a Right Hand Circular Polarization (RHCP). The lower (counterpoise) cone is connected to the inner connection of the shield of the coax providing the out 180 out of phase to the center core that is part of the spiral cone. https://en.wikipedia.org/wiki/Helical_antennaNote that the core of the coax is not cut and is seemlessly part of the spiral, therefore during construction, a large portion of the shield and dielectric plastic must be cut away first. The lower counterpoise is created from sheet copper foil and glued to the the lower form. I recommend self adhesive copper sheets that are at least 2 mils thick (the thicker the better, but a little more expensive). There needs to be a contact from the inner shield to the copper sheet and a rolled or pressed section of the core will work well for this connection. This contact will likely need to be soldered into place to retain it during construction. Also the contact to the foil will also need to be soldered to the foil once in place.There are additional options for the experimenter for either :1. two inter-woven spirals wherein the antenna is configured as a logarithmic helical spiral dipole.https://sergeev.io/projects/spiral-dipole/2. two copper sheets on both cones wherein the antenna is configured as a biconical dipole.https://en.wikipedia.org/wiki/Biconical_antennaAdditional Reference : This model was inspired by a UWB spiral antenna that can be found on thing verse : https://www.thingiverse.com/thing:2152965The issue with the thingverse model is that the coax is in the NEAR FIELD radiation pattern of the antenna and subsequently will suffer from EMI radiaition effects on the outside of the coax. My design is an approach to reduce or eliminate that effect by having the counterpoise surface fold into the *inside* of the coax. Here's where the skin effect depth should be less than the copper sheet thickness.