Antenna Specification Explanation

Antenna Basics and Tips on Antenna Selection  

Selecting the right antenna is a critical step during the design and development steps of any connected device. An antenna must be compatible with the receiver specifications and meet device/application requirements such as size, weight, environmental and mechanical. It is important to understand the antenna capabilities and how the specifications meet the device requirements perfectly. Each antenna has a detailed specifications datasheet that can be found under the product details website section.

This guideline provides additional information that expands each datasheet section with a description to assist our customers in selecting the perfect antenna.

Identify your needs

Mounting Types

The initial step during the antenna selection is to determine what mounting type is suitable to meet the application requirements. In order to select the most optimized antenna, start by confirming if the antenna will be integrated internally, such as a mobile device or externally which often comes with housing for protection in outdoor application and installation.
2J Antennas offers a large selection for internal and external single and combination antenna mounting types.

External Single and Combination Antennas Mounting types

• CONNECTOR MOUNT
  For antennas that require direct PCB mounting solution on devices.
• ADHESIVE MOUNT
  Using a high-grade adhesive option makes it ideal for quick mounting applications.
• SCREW MOUNT
  Offers a secure and permanent installation also in outdoor extreme conditions.
• MAGNETIC MOUNT
  Offers flexibility for temporary installation, strong enough for permanent installations.
• WALL MOUNT
  Can be used for indoor or outdoor installations.
• POLE MOUNT
  Ideal often for marine or construction applications.
• MAGNETIC/ADHESIVE MOUNT
  Offers option of magnetic or adhesive mounting for external installations, especially for non-magnetized metal surfaces.
• WALL/ADHESIVE MOUNT
  Offers option of wall or adhesive mounting for building wall installations.
• VELCRO/ADHESIVE MOUNT
  Velcro provides a perfect solution for temporary use of the antennas.

Internal Single and Combination Antennas Mounting types

• ADHESIVE MOUNT FLEXIBLE
  Small form factor antennas with flexibility for curved installation in devices.
• ADHESIVE MOUNT RIGID
  Using an industrial-grade adhesive layer. This mounting type is ideal for flat surface installations.
• SURFACE MOUNT CERAMIC
  With high-quality ceramic, this surface mount is ideal for a wide range of environments and is compatible with surface mount technique (SMT) allowing for easy PCB integration into small devices.
• SURFACE MOUNT FIBERGLASS
  Fiberglass material allows for the small antenna sizes while offering cost-effective solutions to device designers and is compatible with surface mount technique (SMT) installation.
• THRU-HOLE MOUNT CERAMIC
  The thru-hole mount is typically in the center of the antenna offering extra security for installation for in-device integration.
• SNAP-IN MOUNT MODULE
  Locks the antenna in place, prevents unwanted rotation and facilitates rapid antenna installation and replacement.
• SCREW MOUNT MODULE
  Modular antennas that can be installed on PCB standoffs.

Frequency and Wavelength

The wireless band designated for a device to operate through is called frequency. Antennas are designed to have a range of frequencies to operate within. As an example, if a device is tuned to use Band 17(700MHz), the corresponding antenna must operate within 704 and 746 MHz for transmission and reception.

The wavelength is the distance radio waves travel during one cycle. Designing an antenna quarter wavelength long will provide the best efficiency and deliver the highest signal quality.          

Quarter wavelength is calculated with the following formula:
Quarter Wavelength(mm) = (75/ Freq_MHz)*1,000

IMPORTANT: 4GLTE and 3G/2G antennas have the potential to be used in applications requiring ISM standards. 4GLTE range specification of 698-960MHz and 3G/2G from 824-960MHz, meaning the ISM 868MHz standards operate from 863-870MHz and are located within the 4GLTE and 3G/2G range. The same applies for ISM 915MHz standards that operate within 902-928MHz, or dual band 868/915MHz.

To ensure proper compatibility, please contact our sales department for further analysis.

Fig.1, Examples of 1/4 wavelength; Frequency / Length graph

Standards & Bands

2J Antennas offers antennas that operate within many global standards. As example, our 4G LTE antennas are compatible with Cat-M, Cat-X, Cat-NB, NB-IoT and also SigFox and LoRa, known as LPWA market. The same analogy can apply often to other frequencies. As an example, WIFI antennas can be used for SigFox or LoRa in the 2.4 GHz spectrum.
GNSS antennas are available with pre-filter, mid-filter or no-filter to meet the customers' different requirements. The pre-filter offers the highest resistance and best reception and therefore is standard on all GNSS antennas. It is important to compare active gain and noise on the amplifier of GNSS antennas.

Antenna standards We offer:
- 5GNR/4GLTE/FirstNet/CBRS/LPWA/3G/2G
- 4GLTE/FirstNet/NB-IoT/Cat-X-Mx-NBx/LPWA
- 3G/2G
- 2.4-5.0GHz WiFi/Bluetooth/ISM
- IRIDIUM
- GPS/GLONASS/BeiDou/QZSS/Galileo
- 433/868/915MHz/LPWA/Sigfox/LoRa
  /RFID/ZigBee/ISM
- TETRA/UHF/PMR/LMR
- 169MHz/ERMES/VHF
- DECAWAVE
- DSRC/C-V2X
- ORBCOMM
- AIS
- DAB
- HDTV/DVBT
- AM/FM

Fig.2, Frequency showing Standards Graph

Terms Explanation

Part of antenna selection is not only to identify the specification needs but also compare other products. It is important to understand the parameters in which the antennas are tested and measured to achieve the most reliable performance results. To help our customers find the best product, we have highlighted some of the key points to pay close attention to during antenna selection and comparison.

Testing Parameters

Testing parameters and testing methods can vary from manufacturer to manufacturer. Testing methods should always be fully disclosed such as free space, metal plate, plastic plate, glass, etc. Installing antennas outside of testing parameters will result in undesired antenna performance. For example, if a screw mount antenna is measured in free space showing optimal performance results and is installed on a metal surface in the customer device, the antenna will not operate as expected. 2J Antennas will always disclose the complete measurement conditions to assure our customers get the most accurate data making the in-device integration of an antenna successful.
In order to make a smart product selection between two manufacturers, we encourage that all testing should be completed with a standard length and high-quality cable in order to optimize antenna performance results. No alterations during testing such as shorter or no cables should be performed. This will result in inaccurate efficiency, peak gain and average gain results.

2J Antennas values transparency. This is important when comparing antenna products from different manufacturers.

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.

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.

Table 1, Return Loss to VSWR Conversion Table, and more RF parameters.

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.

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.

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.

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. Please see below table for the relationship between efficiency and average gain:

Table 2, Efficiency/ Average Gain Table

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 doughnut-shaped 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.3.

Fig.3, Radiation Pattern 3D and 2D Graph

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).

General Information / Specification

Ground Plane

2J 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.

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.

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 high-quality 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.

2J Antennas offers a wide range of high-quality connectors and cables as standard and also offers alternatives for any customization needs.

2J Antennas is confident that we have the right antenna for your needs. We offer a wide range of off-the-shelf products, reducing costs during design stages and product life cycle. Our expert team of engineers is available for any customization requirements to meet all our customers' needs.