Chat GPT antenna design.

[VK3YNV]

I went to https://chatgpt.com/ and typed in the following....

i want a design for a 5 element yagi on 440 Mhz

--- It was impressive right up until it presented a diagram of what the yagi should look like..

ChatGPT came back with the following....
Designing a 5-element Yagi antenna for 440 MHz (in the UHF range) requires a few key parameters to ensure it's effective. I'll walk you through the basics of the design, then I'll help with specific dimensions for the elements.
Basic Design Structure for a Yagi Antenna:

1. Reflector (1 element): The reflector is typically about 5-10% longer than the driven element.
2. Driven Element (1 element): This is the element that is connected to the transmitter or receiver.
3. Directors (3 elements): These elements are shorter than the driven element and are positioned in front of it (directional towards the target signal).

Key Parameters:

• Frequency (f): 440 MHz
• Wavelength (λ): The wavelength at 440 MHz is calculated using the formula:
  λ=cf\lambda = \frac{c}{f}λ=fc
  Where ccc is the speed of light (300,000,000 m/s) and fff is the frequency.
  λ=300,000,000440,000,000≈0.6818 m(or 681.8 mm)\lambda = \frac{300,000,000}{440,000,000} \approx 0.6818 \, \text{m} \quad (\text{or} \, 681.8 \, \text{mm})λ=440,000,000300,000,000≈0.6818m(or681.8mm)

Element Lengths:

1. Reflector:
   • Length: λreflector≈1.05×λ2=1.05×681.82≈358 mm\lambda_{\text{reflector}} \approx 1.05 \times \frac{\lambda}{2} = 1.05 \times \frac{681.8}{2} \approx 358 \, \text{mm}λreflector≈1.05×2λ=1.05×2681.8≈358mm
2. Driven Element:
   • Length: λdriven≈λ2=681.82≈341 mm\lambda_{\text{driven}} \approx \frac{\lambda}{2} = \frac{681.8}{2} \approx 341 \, \text{mm}λdriven≈2λ=2681.8≈341mm
3. Directors:
   • Directors are shorter than the driven element, with typical lengths being around 0.9×λ20.9 \times \frac{\lambda}{2}0.9×2λ.
   • Length of each director: λdirector≈0.9×341 mm≈307 mm\lambda_{\text{director}} \approx 0.9 \times 341 \, \text{mm} \approx 307 \, \text{mm}λdirector≈0.9×341mm≈307mm

Spacing between Elements:

1. Reflector to Driven Element: This spacing is typically around 0.2λ0.2 \lambda0.2λ.
   • Spacing: 0.2×681.8 mm≈136 mm0.2 \times 681.8 \, \text{mm} \approx 136 \, \text{mm}0.2×681.8mm≈136mm
2. Driven Element to First Director: Similar spacing to the reflector, also around 0.2λ0.2 \lambda0.2λ.
   • Spacing: 136 mm136 \, \text{mm}136mm
3. Directors Spacing: The spacing between directors can vary, but typically 0.2λ0.2 \lambda0.2λ between each pair of directors.
   • Spacing: 136 mm136 \, \text{mm}136mm

Summary of Element Sizes and Spacings:

• Reflector Length: 358 mm
• Driven Element Length: 341 mm
• Director Lengths (3 elements): 307 mm each
• Spacing Between Elements: 136 mm (for each adjacent pair of elements)

Antenna Design Sketch:

1. Reflector (358 mm)
2. Driven Element (341 mm) connected to the feed line
3. 3 Directors (307 mm each), spaced 136 mm apart

Would you like me to generate a visual design or sketch for better understanding?

Diagram

I’ll generate a simple construction diagram for your 5-element Yagi. One moment!

 

[VK3ZYZ]

Almost looks Steam Punk!