2m Yagi Antenna Analysis

• • In this exercise I am going to analyze the commercial 4-element Yagi 2m antenna shown at the left (click image to enlarge). This is an old antenna that belonged to my dad and the specifications have been lost. We don't even know the vendor.KI6ZHD now has the antenna and before he installs it he would like to look into questions such as:How high should the antenna be mounted?

  • How does vertical vs horizontal mounting over a ground plane change the radiation pattern?

  • What is the bandwidth of the antenna?

  • What is the resonate frequency of the antenna?

KI6ZHD provided detailed measurements and the picture, this exercise is going to provide the answers.

This exercise consists of four main parts and a diversion. You can jump ahead by following these links:

• Part 1: Setting Up the Model

  • Diversion on the Gamma Match

• Part 2: Correcting the model

• Part 3: Answers, Horizontal polarization

• Part 4: Answers, vertical polarized

Preliminaries

The tools I am going to be using are all available on Ubuntu. If you are going to follow along you will need:

• • nec2++ - Antenna Modeling System. The package name is necpp.

  • xnecview - NEC structure and gain pattern viewer. The package name is xnecview.

You can view a short description of all of the antenna modeling programs in the Ubuntu 10.04 repository in my Antenna Modeling Project.

The user's guide for NEC2 is a bit old, but the program itself is even older!

Next - Part 1: Setting Up the Model