K7ZOO 70 cm Parasitic Lindenblad Antenna

thingiverse

This design heavily leverages the previous excellent work by Tony Monteiro (AA2TX), who created and published the paper: “A Parasitic Lindenblad Antenna for 70cm” AMSAT Proceedings 2006. The AA2TX design uses a central driven dipole surrounded by four tilted parasitic elements. The article can be found at this address: https://www.amsat.org/wordpress/wp-content/uploads/2014/01/70ParaLindy.pdf One of the biggest challenges to construct the AA2TX design is holding the parasitic elements in the crazy geometry defined by a Lindenblad configuration. The AA2TX design used irrigation parts, requiring careful alignment by hand and tedious bonding operations. Today with the availability of 3D printing it is possible to remove literally all of the critical alignments, designing these spacings and angles into the 3D printed part! Along with the parasitic element support, another change was made to the AA2TX design: thicker aluminum elements (diameter 0.375 tubing) were substituted in place of 1/8 inch aluminum rod. This change will not significantly change the performance of the design. The larger tubing was chosen primarily to make the assembly more robust for portable operations. QUESTIONS RECEIVED / ANSWERED 1. Is the bottom of the dipole mounted on an insulator, separating it from the mounting pole? Yes, the bottom dipole is mounted on an insulating support. I designed a 3D part that (on the top) held the outer diameter of the lower dipole element, and (on the bottom) coupled to a female threaded PVC fitting... which mounted on my Buddipole mast. 2. What is the diameter of the driven dipole elements? The driven dipole aluminum tubing is 3/4 in diameter, as described by the AA2TX article referenced above.