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Antennas

Antenna selection and design is crucial to achieve satisfactory RF performance of your product. It shall be selected for narrow bandwidth, for use in the 2.4G ISM band (2.4-2.48 GHz) and have minimum loss (typically expressed in S11 parameter or VSWR). The antenna shall be mounted according to the manufacturer’s data sheet. Most types of antennas are not fully omni-directional, consider the radiation pattern of the antenna when placing/positioning it so that it is most efficient in the desired directions. The antenna may be of the type that is terminated with a connector, usually of the TNC or SMA type. You will then need a cable assembly like the one shown below to connect the antenna to the module's on-board I-PEX/U.FL connector.

The other option is to use an antenna fitted with a cable assembly terminated with an I-PEX/U.FL connector that mates with the RF connector on the module.

Cable handling

Not only is the antenna important, but so is the RF path between the antenna and the module. The RF path should be a transmission line with an impedance of 50 ohm. All cables and connectors forming part of the transmission line should be handled with care. It is recommended that, to the greatest extent possible, not to twist or bend the cable.

The onboard U.FL/I-PEX connector requires attention to get a good mating. Ensure it is snapped in place, but avoid using force.

Antenna Placement

A general rule is to allow as much clearance and free space around the antenna as possible. Any object within the path of radiation will interfere with and affect the RF performance.

If you are using a patch-type (stick-on) antenna, it shall be mounted on plastic (preferably PC/ABS if not stated otherwise by the manufacturer) and have proper clearance to surrounding objects, especially ground planes and other metallic objects. If possible, keep any parallel surfaces free from metallic objects. For example, if the PCB is placed right underneath the antenna surface, keep that area free from copper and components. At the very least, apply minimum clearance distances as shown below:



When selecting an antenna for use in the European market, it is essential to ensure that the output power does not exceed 20 dBm, as required by European market regulations. The W-Modbus module has been tested against FCC and IC regulatory requirements and is approved with the antennas described in the following subsections (or electrically equivalent antennas).

LumenRadio, 2.15 dBi dipole omnidirectional antenna

The LumenRadio 2.15 dBi dipole omnidirectional antenna delivers outstanding performance and orientation flexibility. The antenna can be tilted and swiveled and comes with a rugged RP-TNC connector. When combined with the W-Modbus module, the total maximum radiated power is 21.65 dBm (146.2 mW).

Electrical Specifications
Frequency Range 2400-2483.5 MHz
Gain 2.15 dBi
V.S.W.R <2
Nominal Impedance 50 Ohm
Polarization Vertical
Max Power 25 W
Connector RP-TNC
Length 144 mm
Randome material TPEE
Randome Color Black

LumenRadio order code: 104-1001

Molex, 3.2 dBi balanced flex antenna

The molex 3.2 dBi balanced flex antenna is an adhesive omnidirectional flexible antenna. The antenna comes with a 50 mm long cable terminated with a U.FL/ I-PEX MHF connector. When combined with the W-Modbus module, the total maximum radiated power is 22.7 dBm (186.2 mW).

Electrical Specifications
Frequency Range 2400-2483.5 MHz
Gain 3.2 dBi
Return Loss S11 (dB) <-10
Nominal Impedance 50 Ohm
Polarization Linear
Connector U.FL/ I-PEX MHF Connector
Length 50 mm
Mounting Style Adhesive
Packaging Type PET Film
Randome Color Black

LumenRadio order code: 104-1008

Microchip Technology, 0.56 dBi whip monopole antenna

The Lumen Radio 0.5 dBi whip antenna is a high-efficiency compact antenna with exceptional performance characteristics. Its small size (28.4 mm) makes it ideal for use with smaller products. When combined with the W-Modbus module, the total maximum radiated power is 20.06 dBm (101.4 mW).

Electrical Specifications
Frequency Range 2400-2500 MHz
Gain 0.56 dBi
V.S.W.R <1.3
Nominal Impedance 50 Ohm
Connector RP-SMA Male
Length 28.4 mm
Randome material TPEE
Randome Color Black

LumenRadio order code: 104-1034

LumenRadio, 5 dBi outdoor puck antenna

The LumenRadio 5 dBi dipole omnidirectional antenna is well-suited for products enclosed within metal shield. The antenna comes with a 1 m long RG-174 cable terminated with a RP-SMA male connector. When combined with the W-Modbus module, the total maximum radiated power is 24.5 dBm (281.8 mW).

Electrical Specifications
Frequency Range 2400-2483.5 MHz
Gain 5 dBi
V.S.W.R <1.5
Nominal Impedance 50 Ohm
Polarization Vertical
Max Power 25 W
Connector RP-SMA Male
Length 1 m
Height Ø 45 * 25 mm
Randome material ABS
Randome Color Black

LumenRadio order code: 104-1033

Note: The following antennas are not tested against FCC and IC regulatory requirements and are not approved to be used with W-Modbus module in the North American market:

TE Connectivity, 3.2 dBi dipole antenna

The TE Connectivity dipole 3.2 dBi antenna is a dome-type panel mount antenna that is available with different types of termination.

Electrical Specifications
Frequency Range 2400-2483.5 MHz
Gain 3.2 dBi
V.S.W.R <1.9
Nominal Impedance 50 Ohm
Max Power 5 W
Mounting Type Panel Mount
Randome Color Black

LumenRadio order code: 104-1027

TE Connectivity, 2.1 dBi monopole antenna

The TE Connectivity monopole 2.1 dBi antenna is a dome-type panel mount antenna that is available with different types of termination.

Electrical Specifications
Frequency Range 2400-2500 MHz
Gain 2.1 dBi
V.S.W.R <2.2
Nominal Impedance 50 Ohm
Max Power 5 W
Mounting Type Panel Mount
Randome Color Black

LumenRadio order code: 104-1023

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