vhf-uhf-satellite-yagi

Introduction

This repo contains simulations, pictures and 3D models to built your own dual-band 2m (VHF) and 70cm (UHF) yagi. The simulation assumes 4 elements on 2 m and 7 elements on 70 cm. If you need another configuration you must modify the simulation accordingly to determine the new spacings and element sizes.

Note: Consider this project as work-in-progress. I initially did not plan to release this so all of this documentation is written afterwards

Materials needed

The materials I used or this built are:

4 mm aluminium rods for the elements. These are quite fragile, consider using larger aluminum tubes for a more rigid setup
10x10 mm aluminium tube for the boom. If you built a small yagi, you can get away with 1m pre-cut pieces from the hardware store. For the 4/7 elements version I used a 2m rod and cut it to length myself.
coaxial feedline of your choice. I used short runs of RG-58CU cable
cable shoes and M2 screws to attach the coax to the elements. I don't really like this solution. Maybe you have a better idea?
cable ties if you want to mount your coax along the boom
glue of your choice to glue fix the 3d printed element mounts to the boom. I used 2 component adhesive

Note: You can use painters or electrical tape to mark the initial element positions when fitting the 3D printed mounts

Simulations

The simulations are done using MMana-Gal. The design frequencies are 145.9 MHz and 436.5 MHz, the mid point of the 2 m and 70 cm amateurradio satellite band. As this simualtion has two different antennas you must specify the correct driven element to get right results:

w2c is the 2 m driven element
w6c is the 70 cm driven element

Note: Instead of changing the excitation amplitude to the desired element, make sure the the driven element is always source 1 as I ran into aborting simulations when setting the amplitude of source one to zero and the amplitude of source two to one.

3D Files

Currently there is no 3D model of the antenna. Did I already say that I never intend to publish this? ;D Maybe it will come in the future. Included files:

boom handle
standard element mount
driven element mount

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