Antennas come in all sorts of shapes and sizes for various uses. Some must be built-in so as to be both functional and inconspicuous, while others must be fastened externally to the product for proper functioning.
For example, a router will likely need its antenna attached externally; wearable devices or mobile phones would ideally feature integrated antennas into their design instead.
Antenna types for various uses range in terms of their functions as well as size/position considerations. In this post, we have offered insights into antenna types and their applications used with Internet of Things devices, along with factors affecting IoT antennas and much more.
Keep reading this blog for further details.
Types Of IOT Antenna
Dipole Antennas
Omni-directional dipole antennas emit signals in all directions on at least one plane. Due to being half-wavelength structures, these antennas typically measure roughly 6 inches long; cell antennas may even come prepackaged.
In the case of metal box equipment like routers and gateways, though, external dipole antennas may often be included whether preloaded on them directly from manufacturers or ordered separately.
Antenna Dipole Characteristics
Dipole antennas are highly effective due to their reliable polarization, omnidirectional radiation pattern, and steady performance.
Their radiation pattern remains independent from both box size and ground plane size due to the balanced current flow between both antenna arms, which reduces the current flow on the chassis or ground plane. Most energy is released from the broadside of the antenna, releasing a donut-shaped radiation pattern as the dipole antenna separates itself from the chassis (metal box used as a ground plane).
Typical Uses For Dipole Antennas
Dipole antennas provide effective communications in all directions (omni-directional), with little knowledge about where your target receiver link might be, without knowing its position precisely.
Dipoles can be found widely used across Wi-Fi and cellular applications with specific variants dedicated to these forms of communication available from manufacturers and resellers alike.
Any size metal enclosure with an external antenna can effectively accommodate dipole antennas for industrial settings where severe conditions require exterior antenna placement; laboratories also commonly employ dipole antennas as reference antennas due to their efficient performance and consistent radiation pattern.
Monopole Antennas
Small, quarter-wavelength, omnidirectional antennas are called monopoles. Although they might be exterior, they are usually put internally within a device.
Monopole Antenna Properties
Similar to dipole antennas, monopole antennas feature a quarter-wavelength antenna arm. Since it relies on the ground plane as its other half for installation purposes, monopoles may be smaller and easier than dipoles in terms of size and ease.
Note: Radiation patterns depend on ground plane size, cable length, metal enclosure size, as well as external antenna type size (external antenna).
IFA (Inverted F Antenna), usually an IFA trace etched onto a PCB, is one of several aberrations created by monopoly antennas that minimize antenna dimensions while maintaining impedance in narrow bands.
A variation known as Planar IFA or PIFA derives from patch antenna design; typically not etched onto PCB but using wider conductors than IFA for greater efficiency and bandwidth than its IFA cousin; generally, more room is required as wider conductors provide a much broader impedance at narrow frequencies than its IFA counterpart; hence its name as one of the aberrations of its aberrations from its parent monopoly design.
Typical Uses For Monopole Antennas
If your requirement calls for an external, low-cost narrowband antenna but the size of a dipole prevents its use, consider using monopole whip antennas or the more elegant and cost-efficient PIFA approach with its distorted omni-directional radiation pattern instead.
Both types can be made considerably shorter than their respective predecessors while remaining durable mechanically. Cell phone manufacturers frequently utilize IFAs or PIFAs due to their efficiency, bandwidth efficiency and ease of construction.
In contrast, wearable devices often utilize IFAs etched onto PCB boards when embedded wireless devices are being produced as embedded devices with embedded devices.
Loop Antennas
When small, loop antennas typically exhibit omnidirectional characteristics; as their loop width narrows closer to one wavelength, they become bidirectional and less commonly utilized by wireless embedded devices.
This is because they require larger areas to achieve equal radiation efficiencies as monopole or dipole antennas.
Loop Antennas Properties
Since conductors such as metal plates or salt water tend to have greater effects than magnetic ones on electric fields, loop antennas with their dominant magnetic near fields tend to be less affected by them, especially considering our limited magnetic characteristics compared with electronics like wearables.
Keep this in mind: all antennas perform similarly in far fields, but the type of antenna matters much more for performance in near fields.
Typical Uses For Loop Antennas
Loop antennas are widely utilized in wearable devices like fitness trackers and implantable gadgets like pacemakers.
An electric near-field antenna such as a dipole would significantly degrade the performance of an implant nearer the heart than a magnetic near-field loop antenna would.
Helical Antennas
Helical antennas can be defined as miniature monopole antennas coiled into a spiral shape. To reduce the overall height of the bobbin antenna, try wrapping a straight piece of conducting wire around it; its entire length resembles a typical monopole antenna quite closely.
Helical Antennas Properties
Like their counterpart, monopole antennas radiate in all directions, similar to how long-element monopole antennas do.
Helical antennas offer the flexibility of installation in tight places by winding it around in a spiral pattern; their smaller size requires some sacrifice in efficiency or bandwidth for increased size reduction.
Helical Antennas Have Multiple Uses
Due to their extremely compact form factor, helical antennas make great portable communication devices. Equipment operating on lower frequency bands like HF, VHF, and UHF often employs them.
Because many devices operate much smaller than this standard antenna size (e.gA 433MHz monopole antenna would measure approximately 7 inches long), using one for near 50 Ohm impedance is often necessary, something an antenna on such devices might struggle with achieving.
Patch Antennas
As patch antennas are directional, direct line-of-sight communication between devices is necessary for optimal application performance: Only Device A and Device B may communicate at any one time with each other using patch antennas facing in opposite directions - we do not require omni-directional radiation as we always know where each device stands at all times.
Properties Of Patch Antennas
Patch antennas are lightweight, low-profile antennas designed for ease of creation. Although their natural resonance occurs at half their wavelength (like that of dipole antennas), dielectric materials often result in significant reductions to patch size, resulting in extremely narrow bands with reduced dielectric loadings that result in limited volume usage resulting in tiny patch size.
And limited volumes being utilized by dielectric-loaded patches forming narrow frequencies entail limited volume usage and use within narrow volumes (typical of narrowband radio applications).
Patch antennas may even be directly etched onto PCB boards without creating separate tracks; henceforth, they may even be known by names such as "microstrip antennas'' when referred to using microstrip technology).
Patch Antennas Are Widely Utilized
Patch antennas can be invaluable tools in cases when the transmitter and receiver are in direct line-of-sight (loss) paths, and bandwidth is low (low data rates).
One use case is GPS communications using satellites positioned overhead, which require relatively low data rates. Thanks to its low profile design and ability to focus energy directly where it's needed (on a car hood or top, for instance), patch antennas make ideal vehicle monitoring solutions.
Slot Antennas
Slot antennas typically consist of metal plates or PCBs with slots cut out. Each slot radiates similarly to dipole antennas in terms of frequency response but in the opposite direction; their bi-directional radiation patterns make these efficient antennas highly functional; additionally, one end may easily be enclosed within metal enclosures to achieve unidirectional radiation patterns for added ease.
Properties Of Slot Antennas
Slot antennas' low profile and straightforward construction make them highly adaptable. Their original use was television broadcasting.
Size, shape, and driving frequency all influence an antenna's radiation pattern.
Typical Uses Of Slot Antennas
When an external antenna cannot be utilized due to metal enclosures, slot antennas provide the ideal solution. They are most commonly utilized on aircraft and naval vessels when external antennas pose risks to their surroundings and navigation systems require navigation data without interference from external antennas.
Read More: Embrace IoT for Business Success: Unlock Connectivity
Factors Affecting The Choice Of Antennas For Internet Of Things Applications
Here are some important factors influencing IoT antenna choice as follows: An antenna choice for Internet of Things designs depends on many parameters, including deployment location, size, precision, and frequency band.
IoT antennas often operate unlicensed ISM (industrial, scientific and medical) band frequencies at particular ranges - each antenna being tailored specifically towards certain uses.
Wi-Fi and Bluetooth may work fine for wearable devices like wearables, game consoles, IP cameras , and portable devices while for industrial uses like smart cities Industry 4.0 smart agriculture etc.
IoT frequencies will likely be required as these specifications offer better coverage of these frequency bands than their counterparts do.
Your IoT antenna should look attractive within its product container and deliver maximum performance. An optimally placed, small antenna may even offer greater gains with minimal power usage.
However, coverage must still occur effectively with minimum consumption. Sometimes, antenna topology plays an equally crucial role as size; its influence extends across bandwidth, radiation pattern, gain, and overall efficiency of antennas.
Readers might wonder whether to choose custom-designed or off-the-shelf antennas. While off-the-shelf options with satisfactory product performance standards might be less expensive, designers may experience difficulty fitting such antennas into very limited designs.
Stiffness may also impact antenna performance; therefore, investing in a custom-made antenna is the ideal solution to ensure optimal results.
When selecting an IoT antenna from any part of the world, regulatory standards need to be considered in addition to SAR criteria like Radio Equipment Directive (RED), Electromagnetic Compliance, or FCC Class A/B Rules should also be taken into consideration. In summary, the most important factors to take into account while choosing an antenna are,
- Kind of antenna
- Operating frequency range, coverage, range, gain of the antenna, radiation pattern, and
- FoV
- Antenna size and form
- Price
A Few Guidelines For Placing Antennas In The Internet Of Things Devices
An IoT design relies heavily on selecting an antenna with which it connects wirelessly. Yet, this choice alone will not solve issues related to high RF performance.
Battery life for these devices depends heavily on antenna performance - its success can depend on factors like proximity between components, usage of the ground plane, signal interference from nearby electronics components or proximity between human bodies etc.
As part of their design phase, developers should give these considerations their full consideration, and care should be applied during the design phase development process.
Here we have outlined the important IoT antenna placement tips:
- For optimal antenna performance on PCB boards, ensure there is sufficient keep-out space by placing it near one corner.
- To maximize antenna effectiveness, use a ground plane of appropriate width and clearance.
- Shipping antennas should be avoided near plastic. Doing so may alter their resonance frequency due to plastic's higher dielectric constant compared to air. Antennas must not feature metallic cages covering them when shipped.
- For maximum radiation in a particular direction, antenna placement must coincide with that of the finished product.
Conclusion
Antennas that are highly compact, high gain and efficient are revolutionizing the design and development of wireless Internet of Things devices, yet one of the biggest design issues remains selecting an antenna suitable for IoT use.
An antenna designed with quality materials ensures high performance, extended range and minimal power usage.
Developers seeking optimal size and performance characteristics for Internet of Things applications should carefully consider custom antenna designs, even though many off-the-shelf options exist with appropriate frequencies for IoT applications.
Reach out to us to gain more knowledge on designing custom IoT antenna solutions as well as selecting and integrating antennas that complement small form factor IoT devices.
