My ADS-B setup

Maximum distance that an ADS-B signal can be detected

Theoretically the furthest away you can detect an aircraft flying at 40,000ft is 391 km (211 Nautical Miles or 243 Miles). This is because the earth is round and you require ‘Line of Sight’ (LOS) between you and the aircraft to detect the ADS-B signal. Once the aircraft if further than 243 miles you no longer have LOS as the aircraft is below the horizon and the crust of the earth is now in the way! This all assumes your receiver is located at sea level and there are no hills or buildings in the way.

To increase the detection range beyond 243 miles you need to either:
(1) Raise either your antenna. Ben Nevis is the tallest mountain in the UK at 1,345 meters and from here your range for detecting an aircraft at 40,000ft would increase by 9Km (5.6 miles)
(2) Have the aircraft fly higher. An aircraft at 60,000ft could be detected from 479 KM (258 Nautical Miles or 297 Miles)

Be nice to the 0.000,000,000,001 w of signal that arrives at your antenna!

Quick math to prove the above statement:

  • Minimum transmission power required by an ADS-B equip aircraft flying above 15,000ft = 125 Watts (21 dBw)
  • Gain of aircraft antenna (quarter-wave monopole) = 5.14 dBi
  • Attenuation of signal as it travels through 391km of air to get to you = 145.0 dB

Therefore, power reaching your location (dBw) = transmission power (dBw) + Transmitting Antenna Gain (dBi) – Attenuation due to distance traveled through air (dB)

= 21 + 5.14 – 145.03
= -118.89 dBW ( 0.000000000001291 Watts )

My Set Up

Description Gain Photo
Antenna

FlightAware 1090Mhz ADS-B N-Type Antenna. 66cm /26″

Amazon

5.5 dBi
FlightAware 1090MHz ADS-B N-Type Antenna 26" - 5.5dBi
FlightAware 1090MHz ADS-B N-Type Antenna 26″ – 5.5dBi
Coax

0.75 meters of Andrew Heliax LDF4-50A

Terminated both ends with L4TNM-PSA N-Type Male

LDF4-50A Specification

N-Type Connector specification

Cable = -0.06 dB
Connector = -0.05 dB (each)
Andrew Heliax LDF4-50A
Andrew Heliax LDF4-50A
L4TNM-PSA N-Type Male for LDF4-50A
L4TNM-PSA N-Type Male for LDF4-50A
Low Noise Amplifier

KU LNA 1090-2 A TM
1,070 to 1,110 Mhz

KUHNE electronic shop

30 dB
KU LNA 1090-2 A TM, Selective Low Noise Amplifier
KU LNA 1090-2 A TM, Selective Low Noise Amplifier
Coax

7.25 meters of Andrew Heliax LDF4-50A

Terminated both ends with L4TNM-PSA N-Type Male

Cable = -0.55 dB
Connector = -0.05 (each)
Andrew Heliax LDF4-50A
Andrew Heliax LDF4-50A
L4TNM-PSA N-Type Male for LDF4-50A
L4TNM-PSA N-Type Male for LDF4-50A
Bias T

KU BT 6000 N
10 to 6,000 Mhz

KUHNE electronic shop

-0.6 dB
KU BT 6000 N, Bias Tee
KU BT 6000 N, Bias Tee
Pig Tail

N Male to MCX Male Right Angle Adapter RG316 Coaxial Cable 20cm

Amazon

-0.5 dB
N Male to MCX Male Right Angle Adapter RG316 Coaxial Cable 20cm
RG316 PigTail
DVB-T Tuner
NooElec NESDR Mini 2 SDR & DVB-T USB Stick (RTL2832 + R820T2)

Net Gain = 34.58 dB