ANTENNA DESIGNING FOR IOT

ANTENNA DESIGNING FOR IOT

“Antenna” is considered to be the heart of wireless communication. In this modern technological era, IoT is becoming a trending technology that enable us to communicate smartly with the devices wirelessly by sending and receiving signals with the help of antennas. There is no universal antenna that works good for all devices. So it is necessary to develop antennas for each and every new device in order to suffice the device’s requirements and for better performance.

ANTENNA DESIGNING PROCESS FOR IOT:

PHASE-1:REQUIREMENT,SPECIFICATION,SELECTION:

This phase look into the requirements and specification i.e)the parameters of the antenna like operating frequency,impedance,bandwidth,return loss,radiation pattern,gain,total efficiency and polarisation. It also includes selection of best type of antenna by considering different surroundings and different user interface of the device.

PHASE-2:MODELLING AND SIMULATION

This phase look into the hardware concepting and hardware development of whole iot device including antenna and with the help of 3D tool 3D modelling of antenna along with the whole device is done. The EM simulation of antenna is also done to optimize the performance of the whole device.Incase of selecting integrated antenna,the detailed PCB routing is done with the help of 3D simulation tool.

PHASE-3:PROTOTYPING AND ANALYSING

This is the phase where the final tuning of antenna is done.It includes prototyping the whole iot device with antenna and includes analysis of RF characteristics of antenna in order to check the assembly stability and performance of the device. While analysing, if the parameters of antenna is not matched exactly with the device’s antenna requirements ,we loop into the phase-2 and again final tuning will be done.

There are many types of antenna but in terms of using antenna for IoT devices,the antennas are categorised into:

1.  EXTERNAL ANTENNAS: Antennas connected to device by co-axial cable and are placed away from main PCB of the device

•       OFF THE SHELF ANTENNAS:whip dipole,PCB antenna,dipole,GPS patch antenna.
•       DEDICATED ANTENNAS:dual band antenna,PIFA antenna,CBSA.

2.  INTEGRATED ANTENNAS: Antennas are integrated in device’s own PCB

•      OFF THE SHELF ANTENNAS:chip antenna,PCB antenna.
•      DEDICATED ANTENNAS:loop antenna,GPS PIFA antenna,LoRa PIFA antenna,wire antenna.

FACTORS TO BE CONSIDERED WHILE DESIGNING ANTENNAS FOR IOT:

1) ANTENNA IMPACT RADIO LINK BUDGET:

Radio link budget is the number which defines the network coverage area.Based on the link budget, the base station is located.

Link budget=device radiated power – base station radiated sensitivity.If there is no fluctuation in between device and base station,the link budget will be high.But while evaluating ,the path loss may be impacted by buildings,tress etc..which will decrease the link budget.The omni parameters can reduce the link budget,therefore the coverage area for device is the actual coverage by antenna itself.

2) IMPORTANT ANTENNA PARAMETERS FOR IOT DEVICES:

•       Impedance
•       Return loss(dB)=10*log10(P reflected/P incident)
•       Bandwidth
•       Efficiency:total efficiency(dB)=10*log10(P radiated/P incident)

3) NEAR FIELD AND FAR FIELD REGIONS:

Space around the antenna is divided into two regions:

•       Near field region < 2D^2/lambda
•       Far field region>2D^2/lambda

Where D-maximum linear dimension of antenna

Lambda-wavelength of EM waves

In near field region,reactive fields is predominant.i.e)fields looping back to antenna.so objects in near field region will impact antenna’s behaviour and characteristics

In far field region,radiating field is predominant.i.e)fields move away from antenna).So objects in far field region will impact only the propagation of EM waves not the antenna characteristics.

4) ANTENNA’S  SENSITIVITY TO NEARBY ENVIRONMENT:

With the help of VNA(Vector Network Analyser),the sensitivity of simple dipole antenna is analysed in different practical cases.

Case 1:when antenna is stand alone,inital tuning occurs

Case 2:when antenna is against metal plate,strong detuning occurs

Case 3:when antenna is hold with hand,strong detuning occurs

Case 4:when antenna is against wooden board,moderate detuning occurs

From these case studies ,we inference the sensitivity of antenna with respect to its environment.

5) ANTENNAS SENSITIVITY TO DEVICE’S DESIGN &IMPLEMENTATION:

• Incase of small devices with small antennas,it is not only the antenna is radiating but also the whole device is radiating
• Incase of selecting PCB antenna for integration,Size of PCB will impact antenna performance

•  Casing /housing of device with plastic/ABS material will impact antenna performance
• Other components like battery,wires..will impact antennas performance
•  Incase of integrated antenna,Location of antenna in main PCB of device will impact antenna performance
• Antenna’s volume will impact antenna performance

Thus antennas are not the standard components and relevant antenna designing is quite essential for every IoT device.