Ultimate Guide to Choosing the Right Antenna

Understanding which antenna might be the best choice for you sometimes become difficult. Choosing the right antenna is crucial for maximising signal strength and ensuring seamless communication, whether you're on the move, at home , or in a tough building. In this guide, we will try to help walk you through the different types of antennas, their specific uses, and how to pick the perfect one for your needs.

Antenna Basics: Key Concepts to Understand

Before diving into specific antenna types, let's cover the fundamentals first:

Gain (dBi): 

Antenna gain measures how well an antenna converts radio waves into electrical signals (for receiving) or vice versa (for transmitting), and in which direction it does so. It's measured in decibels relative to isotropic (dBi). A higher dBi value generally means a stronger signal and greater range, but it's not the only factor. For a directional antenna, higher gain means the antenna provides a strong signal in a specific direction with lower coverage.

Directionality:

Directionality refers to the direction in which an antenna sends or receives signals most effectively.

• Omni-Directional: This type of antennas send and receive signals in a 360-degree horizontal pattern. It is like a bare lightbulb, spreading light all around.
• Directional: This type of antennas focus their power in a specific direction, much like a spotlight.

Polarisation:

This refers to the orientation of the electric field of the radio wave. Vertical polarisation is common for cellular signals. But, it important that both the transmitting and receiving antennas have matching polarisation for optimal performance. 

Frequency Bands:

Antennas are designed to operate effectively over specific frequency ranges (bands). Cellular networks (3G, 4G, 5G) use various bands. 3G is being phased out in Australia. So, only 4G and 5G bands are in operation. Some of the bands used by telecom operators like-

• Telstra uses 700MHz, 900MHz, 1800MHz, 2100MHz, and 2600MHz for 4G, and 3.5 GHz for 5G. 
• Optus uses 700MHz, 1800MHz, 2100MHz, 2300MHz, and 2600MHz for 4G. 
• Vodafone uses 850MHz, 1800MHz, and 2100MHz for 4G. 

It's important to consider the bands used by your carrier and device while purchasing an antenna.

Impedance:

Antenna impedance is a term used to refer the amount of resistance an antenna presents to the flow of alternating current (AC). This is calculated in ohms (Ω). It is a crucial factor to ensure efficient power transmission between the transmitter, receiver (booster), and antenna. A mismatch of impedance between the antenna and booster can lead to signal reflections and power loss. Most cellular antennas and devices use a standard impedance of 50 ohms for maximum power transfer.

VSWR (Voltage Standing Wave Ratio):

VSWR is a term used to measure how efficiently radio-frequency power is transmitted from a power source, through a transmission line, into a load (e.g., from a booster to an antenna).  A low VSWR (close to 1:1) is ideal, indicating good impedance matching and minimal signal reflection. 

Note on checking VSWR: 

It requires specialised equipment (like a VSWR meter or antenna analyser) to measure VSWR directly. These type of equipment is normally used by professional installers. Customers can help ensure good VSWR by selecting high-quality, 50-ohm compatible antennas and cables, ensuring all connections are secure and clean. It would also help with a proper installation by professional hands. Symptoms of very high VSWR can include significantly reduced performance or equipment overheating.