5 dBi Antenna Range Calculator

Introduction

This tool computes the maximum range or distance that can be achieved with a 5 dBi gain antenna.

The system includes a transmitter, receiver, antennas and cables.

Calculator

To calculate the max distance, enter the following:

  • Frequency of operation (Hz/KHz/MHz/GHz)
  • Transmit Power (dBm)
  • Receiver Sensitivity (dBm)
  • Receive Antenna Gain (dBi) – the default value is 2 dBi
  • Total Cable and Other Losses (dB)

Formula

The calculator uses the Free Space Path Loss (FSPL) equation:

PTx – PRx = 20*Log10(d) + 20*Log10(f) + Lc + 20*Log10(4Ï€/c) – GTx – GRx

The distance d is given by

Log10(d) = (1/20)*(PTx – PRx – Lc + GTx + GRx – 20*Log10(f) – 20*Log10(4Ï€/c))

Example Range Calculation

At a frequency of 2450 MHz (Wi-Fi band) and transmit power of +20 dBm, let’s calculate the range for a 5 dBi transmit and receive antenna

With

  • Receiver sensitivity = -90 dBm,
  • Cable loss = 0 dB

the maximum range is 9,737 meters or 9.74 km.

Important to remember that this calculation is outdoors and in free space which represents an ideal signal propagation condition. In practice, the range would be lower.

If you want to use a 5 dBi (receive) antenna for TV signal reception, use the calculator above. Consider the frequency of operation, transmitter power (in the kW range) and transmit antenna gain.

How to use the Calculator

Below is a list of the terms used in the calculator and what each of them mean.

Frequency of operation

This is the frequency at which the communication system operates. At lower frequencies, wavelength is commonly used and if that’s the case, then use the wavelength to frequency converter.

Transmit Power

This is the power at the output connector of the transmitter. It is usually specified in dBm. However many vendors specify this quantity in Watt. Convert from Watt to dBm.

Transmit Antenna Gain

This depends on the type of antenna used and is expressed in dBi (dB relative to isotropic antenna).

Total Cable and Other Losses

This includes losses between connectors and antennas. If RF Splitters are used, the loss should be accounted for as well. It is specified in dB. Use this calculator to find the loss due to antenna cable.

The sum of the Transmit antenna power and Gain minus cable and connector losses is also called Effective Isotropic Radiated Power or EIRP for short.

Receiver Sensitivity

Minimum level of input signal that a radio receiver can detect and demodulate. Use this calculator to find the sensitivity as a function of temperature, SNR and receiver noise figure.

Receive Antenna Gain

Depends on antenna used and is expressed in dBi. In cases where the signal is from a particular direction, a high gain antenna (8 dBi for instance) can be used. This allows focusing of energy instead of receiving from all directions. Antenna gain can be calculated from the Antenna Factor and frequency of operation.

Background

What is a 5 dBi Antenna?

A 5 dBi antenna is a type of antenna that has a gain of 5 decibels over an isotropic radiator (hence the i suffix), which is a theoretical antenna that radiates power equally in all directions. The “dBi” metric is used to compare the gain of antennas, indicating how much more effectively an antenna can transmit or receive a signal in specific directions compared to the isotropic radiator.

Applications

5 dBi antennas are commonly used in various applications where a balance between range and coverage area is needed. Their moderate gain makes them suitable for a variety of scenarios, both in consumer electronics and in more specialized fields.

The picture below illustrates the trade-offs between antenna gain and coverage.

Here are some common uses for 5 dBi antennas:

  1. Wi-Fi Routers and Access Points: Many home and small office routers come with 5 dBi antennas to provide an optimal balance of range and coverage within indoor environments. These antennas help to improve signal strength and quality over the basic antennas that might come with lower-end devices.
  2. Wireless Network Adapters: USB or PCI wireless network adapters for computers often use 5 dBi antennas to enhance signal reception and transmission, improving connectivity with Wi-Fi networks.
  3. IoT Devices: Internet of Things (IoT) devices, which require reliable connectivity over moderate distances without consuming too much power, often use 5 dBi antennas. These can include smart home devices, agricultural sensors, and industrial monitoring equipment.
  4. Outdoor Wireless Bridges: For relatively short-range outdoor wireless communication links, such as connecting two buildings on the same property, 5 dBi antennas can offer the necessary range and signal quality, especially when line-of-sight is clear.
  5. FPV (First Person View) Systems: In drone or remote-controlled vehicle applications, 5 dBi antennas can be used for the video transmission system to provide a good balance between range and signal penetration.
  6. Mobile and Portable Devices: Some portable devices, such as mobile broadband hotspots or long-range Wi-Fi client devices, might use 5 dBi antennas to enhance their connectivity when moving between different environments.
  7. Amateur Radio: Ham radio operators might use 5 dBi antennas for certain VHF/UHF applications where they need a slight gain over an omnidirectional antenna without resorting to highly directional antennas that require precise aiming.

The choice of a 5 dBi antenna typically reflects a compromise between wider coverage area (which would benefit from a lower-gain, more omni-directional antenna) and longer range or better penetration through obstacles (which would benefit from a higher-gain, more directional antenna).

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