Antenna Parameters Explanation

1. Return Loss
The return loss is measured in decibels (dB) and represents how much energy is transferred from the device to the antenna. The lower the measurement the better. For a 50 Ohm system, it is recommended to have a minimum of -5dB or better measurement. Using the return loss to identify how the impedance of the antenna performs across the entire spectrum can help to estimate the bandwidth and operating frequencies.

2. VSWR
Voltage Standing Wave Ratio (VSWR) is another parameter used to measure how much energy is transferred from the device to the antenna but with a different mathematical scale than the one used for Return Loss. The lower the measurement the better, meaning closer to a 50 Ohm system and it is recommended to have a maximum of 3.5 VSWR. Please review the table below to learn more about the relationship between Return Loss and VSWR as well as other RF parameters and values.

3. Bandwidth
Bandwidth is a range of frequencies. A short frequency range is a narrow band and wider frequency range is categorized as a wideband. It is important to select the right antenna with the matching bandwidth as narrowband and wideband are not interchangeable.

4. Efficiency
Antenna efficiency (radiation efficiency) is a measure of the electrical efficiency in which a radio antenna converts the radio frequency power received into radiated power. In other words means how much energy is radiated from the antenna to the air, how good is the antenna to radiate the energy. Being the most important parameter of an antenna in mobile communications. 100% means all energy radiated, 50% means half energy radiated, the minimum recommended is 25% but in some cases can go down to 10%, but the higher the better.

5. Peak Gain
Antenna gain is the measurement of an antenna’s ability to direct or concentrate radio frequency energy in a particular direction or pattern. This is typically measured in dBi (Decibels relative to an isotropic radiator). The most crucial parameter in mobile communication is antenna efficiency followed by peak gain. Efficiency measures how much energy is in the air radiating in all directions, while peak gain is only measured in a single direction. While in fixed communication the most important parameter is the peak gain, since all the energy must be concentrated in one single direction.
This value comes from a single point in the radiation pattern being the maximum point in the 3D sphere.

6. Average Gain
Similar to efficiency, the average gain is represented with a different mathematical scale (dB) and takes into consideration any mismatch losses. 100% is 0 dB which is maximum radiated energy, 50% is -3 dB which is half of the radiated energy, etc.

7. Polarization
Polarization is the orientation of the electric field of an electromagnetic wave. The two most common polarizations are linear and circular. Measurement and changes of polarization are determined in which the wave transmits through the environment from the transmitting to the receiving antenna.
With linear polarization, the electric field vector stays in the same plane were in with circular polarization, the electric field vector is rotating with circular motion completing a full turn for each RF cycle. This rotation can be completed right-hand (RHCP) or left-hand (LHCP).

8. Radiation Patterns
The radiation pattern of an antenna is the strength of radio waves transmitted by the antenna traveling in different directions and angles.
Omnidirectional antennas offer a 360-degree doughnutshaped radiation pattern that is uniformly distributed in all directions and are ideal for connecting devices that are on the same plane and to either side of each other. Hemispherical antennas distribute their radiation over a hemisphere (half of the space). Directional antennas radiate into one targeted direction allowing for longer transmission distances with less interference.
The plot graph will show how the energy is being radiated to the air in 3 dimensional or 2 dimensional pattern. In 2D graph pattern, the horizontal and vertical planes are shown. See example in the graph below Fig.

9. Ground Plane
Dinobell Antennas offers both, ground plane dependent and ground plane independent antennas. A ground plane is a surface area or metal that acts as a conductor and reflects the radio waves from other antenna components. The shape, size and the required clear area of the ground plane play an important role in determining radiation characteristics and gain.
Low-frequency antennas such as broadcast antennas accept large conducting masses such as the earth or ocean as a sufficient ground plane. For very high frequency (VHF) and ultra-high frequency (UHF) antennas, the ground plane can be smaller and a metal disk, screen or wire is used as a ground plane. In automotive, marine and air equipment metal housing (car / airplane / boat) can serve as a sufficient ground plane.
As a general rule, the conduction surface must be at least a quarter of the wavelength of the radio waves in diameter and in ideal condition the bigger the ground plane the better control of the electrical performance is achieved.between Return Loss and VSWR as well as other RF parameters and values.

10. Maximum Input Power
The Maximum Input Power is the maximum amount of power (in Watts) that can be transmitted to one antenna port without damaging it while maintaining performance.

11. Cable and Connector Types
The correct selection of RF cable and connector types is critical to proper antenna function. The connector serves as a mechanical connection between the antenna and RF system and the cable is the transmission line for radio frequency signals connecting transmitters and receivers. The cable lengths impact signal quality and strength. Selecting a highquality cable and connector that is compatible with the antenna will ensure optimal antenna performance. When considering a product, it is important to determine the correct connector gender, polarity and geometry as well as the cable length prior to a quote request.
Dinobell Antennas offers a wide range of high-quality connectors and cables as standard and also offers alternatives for any customization needs.