Advantages of upgrading from 1.5m dish to 2m dish for hydrogen line radio astronomy
The following comes from CHATGPT, when I asked it this question April 2025:
Upgrading from a 1.5 m dish to a 2 m dish for observing the 1420 MHz hydrogen line will yield noticeable improvements in both sensitivity and angular resolution:
1. Sensitivity (Gain/Collecting Area)
- Dish area scales with the square of the diameter:
- 1.5 m dish area = π(0.75)² ≈ 1.77 m²
- 2.0 m dish area = π(1.0)² ≈ 3.14 m²
- This is a 77% increase in collecting area, meaning the system gain improves by roughly 3 dB.
- Practical effect: Fainter HI signals become detectable, improving SNR and reducing integration time for a given SNR.
2. Angular Resolution
- Beamwidth is approximately:
θ ≈ 70 × (λ / D) degrees
where λ = 0.21 m (for 1420 MHz)- 1.5 m dish: θ ≈ 70 × (0.21 / 1.5) ≈ 9.8°
- 2.0 m dish: θ ≈ 70 × (0.21 / 2.0) ≈ 7.4°
- That’s about a 25% improvement in angular resolution, sharpening your sky maps.
Summary:
- Stronger signal detection (more HI structure detail in fainter regions)
- Better spatial resolution (finer map features)
- Longer dish does require tighter mechanical alignment and feed positioning, and more precise pointing.