Antenna Measurement Made Easy

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Covering the Basics

If you’re doing any kind of wireless communications application, that probably means including an antenna in your design. The science of antennas is complex. But here Robert shows how the task of measuring an antenna’s performance is less costly and exotic than you’d think.

By Robert Lacoste

Now that wireless communications is ubiquitous, chances are you’ll be using Bluetooth, Wi-Fi, cellular, LoRa, MiWi or other flavor of wireless interface in your next design. And that means including an antenna. Unfortunately, antenna design is not an easy topic. Even very experienced designers sometimes have had to wrestle with unexpected bad performances by their antennas. Case in point: Google “iPhone 4 antenna problem” and you will get more than 3 million web pages! In a nutshell, Apple tried to integrate a clever antenna in that model that was threaded around the phone. They didn’t anticipate that some users would put their fingers exactly where the antenna was the most sensitive to detuning. Was it a design flaw? Or a mistake by the users? It was hotly debated, but this so-called “Antennagate” probably had significant impact on Apple’s sales for a while.

I already devoted an article to antenna design and impedance matching (“The Darker Side: Antenna Basics”, Circuit Cellar 211, February 2008). Whether you include a standard antenna or design your own, you will never be sure it is working properly until you measure its actual performance. Of course, you could simply evaluate how far the system is working. But how do you go farther if the range is not enough? How do you figure out if the problem is coming from the receiver, the transmitter, propagation conditions or the antenna itself? My personal experience has been that the antenna is very often the culprit. With that in mind, it really is mandatory to measure whether or not an antenna is behaving correctly. Take a seat. This month, I will explain how to easily measure the actual performance of an antenna. You will see that the process is quite easy and that it won’t even need costly or exotic equipment.

SOME ANTENNA BASICS

Let’s start with some basics on antennas. First, all passive antennas have the same performance whether transmitting or receiving. For this article, I’ll consider the antenna as transmitting because that’s easier to measure. Let’s consider an antenna that we inject with a given radio frequency power Pconducted into its connector. Where will this power go? First off, impedance matching should be checked. If the impedance of the antenna is not well matched to the impedance of the power generator, then a part of the power will be reflected back to the generator. This will happen in particular when the transmit frequency is not equal to the resonant frequency of the antenna. In such a case, a part of Pconducted will be lost.  That is known as mismatch losses: Pavailable= Pconducted – MismatchLosses. While that itself is a very interesting subject, I have already discussed impedance matching in detail in my February 2008 article. I also devoted another article to a closely linked topic: standing waves. Standing waves appear when there is a mismatch. The article is “The Darker Side: Let’s play with standing waves” (Circuit Cellar 271, February 2013).

For the purpose of discussion here, I will for now assume that there isn’t any mismatching—and therefore no mismatch loss. …

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Arduino Board Pair Boasts LoRa and GSM Capabilities

Arduino has introduced a pair of new Internet-of-Things (IoT)  boards with embedded LoRa and GSM capabilities. The boards were first unveiled at World Maker Faire New York. The Arduino MKR WAN 1300 and MKR GSM 1400 enable system developers to quickly add connectivity to their projects and ease the development of battery-powered IoT edge applications. Both of the highly compact boards measure just 67.64 mm x 25 mm, together with low power consumption, making them an ideal choice for emerging battery-powered IoT edge devices in the MKR form factor. Suitable applications examples include environmental monitoring, tracking, agriculture, energy monitoring and home automation.

Arduino DKb9irAW4AAM320-1Offering 32-bit computational power similar to the Arduino MKR ZERO board, the MKR WAN 1300 is based around the Murata LoRa low-power connectivity module and the Microchip SAM D21 microcontroller, which integrates an ARM Cortex-M0+ processor, 256 KB Flash memory and 3 2KB SRAM. The board’s design includes the ability to be powered by either two 1.5 V AA or AAA batteries or an external 5 V input via the USB interface—with automatic switching between the two power sources.

In addition, the MKR WAN 1300 offers the usual rich set of I/O interfaces expected with an Arduino board, and ease of use via the Arduino IDE software environment for code development and programming. Other features  include an operating voltage of 3.3 V; eight digital I/Os; 12 PWM outputs; and UART, SPI and I2C interfaces.

Like the MKR WAN 1300, the Arduino MKR GSM 1400 is based on the SAM D21, but integrates a u-blox module for global 3G communications. The board features automatic power switching, however, it uses either a 3.7 V LiPo battery or an external Vin power source delivering 5 V to 12 V. While the USB port can also be used to supply 5 V to the board, the MKR GSM 1400 is able to run with or without the battery connected.

The MKR GSM 1400 provides a rich set of I/O interfaces including: eight digital I/Os; 12 PWM outputs; UART, SPI and I2C interfaces; analog I/O including seven inputs and one output; and eight external interrupt pins. Both boards are now available for pre-order on the Arduino Store.

Arduino | www.arduino.cc

STMicro and Objenious Collaborate on IoT LoRa Network Deal

STMicroelectronics and Objenious are working together to accelerate the connection of IoT nodes to LoRa networks. ST’s development kits certified on the Objenious network are available now, greatly reducing R&D effort and time to market in the creation of new LoRa devices.

STM32 Nucleo LoRa kits are now certified and available to developers through ST sales channels.

STM32 Nucleo LoRa kits are now certified and available to developers through ST sales channels.

LoRAWAN is a Low Power Wide Area Network (LPWAN) based on LoRa technology that is opening up a world of possibilities to create networks of connected devices ideal to address a broad range of IoT applications. The benefits of LoRa especially suit applications where nodes have limited power capability, can be difficult to access, and data transfers don’t require high bandwidth. LoRa can target a wide spectrum of applications such as tracking, proactive maintenance, and many others. Industry analysts estimate there will be tens of billions of connected devices deployed in the world by 2020.

Objenious launched and operates the first LoRa network in France, with more than 4,200 antennas deployed around the country. Leveraging the network know-how inherited from Bouygues Telecom, Objenious now proposes its LoRa network, platform, and services for LPWAN IoT to partners and customers locally and internationally thanks to roaming agreements.

STMicro helps developers by providing tools and software libraries that aid the STM32 MCU-based embedded design as part of its freely available STM32 Open Development Environment (ODE). By integrating Objenious’ network access software on top of the STM32 ODE, developing connected devices is even easier. STM32 Nucleo LoRa kits are now certified and available to developers through ST sales channels.

STMicroelectronics | www.st.com

IoT Sensor Node Gets LoRaWAN Certification

Advantech offers its standardized M2.COM IoT LoRaWAN certified sensor node WISE-1510 with integrated ARM Cortex-M4 processor and LoRa transceiver. The module the  is able to provide multi-interfaces for sensors and I/O control such as UART, I2C, SPI, GPIO, PWM and ADC. The WISE-1510 sensor node is well suited for for smart cities, WISE-1510_3D _S20170602171747agriculture, metering, street lighting and environment monitoring. With power consumption optimization and wide area reception, LoRa  sensors or applications with low data rate requirements can achieve years of battery life and kilometers of long distance connection.

WISE-1510 has has received LoRaWAN certification from the LoRa Alliance. Depending on deployment requirements, developers can select to use Public LoRaWAN network services or build a private LoRa system with WISE-3610 LoRa IoT gateway. Advantech’s WISE-3610  is a Qualcomm ARM Cortex A7 based hardware platform with private LoRa ecosystem solution that can connect up to 500 WISE-1510 sensor node devices. Powered by Advantech’s WISE-PaaS IoT Software Platform, WISE-3610 features automatic cloud connection through its WISE-PaaS/WISE Agent service, manages wireless nodes and data via WSN management APIs, and helps customers streamline their IoT data acquisition development through sensor service APIs, and WSN drivers.

Developers can leverage microprocessors on WISE-1510 to build their own applications. WISE-1510 offers unified software—ARM Mbed OS and SDK for easy development with APIs and related documents. Developers can also find extensive resources from Github such as code review, library integration and free core tools. WISE-1510 also offers worldwide certification which allow developers to leverage their IoT devices anywhere. Using Advantech’s WISE-3610 LoRa IoT Gateway, WISE-1510 can be connected to WISE-  PaaS/RMM or  ARM Mbed Cloud service with IoT communication protocols including LWM2M, CoAP, and MQTT. End-to-end integration assists system integrators to overcome complex challenges and helps them build IoT applications quickly and easily.

WISE-1510 features and specifications:

  • ARM Cortex-M4 core processor
  • Compatible support for public LoRaWAN or private LoRa networks
  • Great for low power/wide range applications
  • Multiple I/O interfaces for sensor and control
  • Supports wide temperatures  -40 °C to 85 °C

Advantech | www.advantech.com

Kickstarter Enables Building LoRa IoT Gear in 3 Steps

Electronic Cats has launched a Kickstarter campaign called LoRaCatKitty to enable the building of Internet of Things (IoT) applications with LoRa in just three steps. LoRaCatKitty is designed to simplify the development of IoT applications using LoRa technology. It has based its development on the ESP8266 WiFi module and the LoRa RN2903 or RN2483 Microchip module.

LoRAKitty

The mobile application for LoRaCatKitty, allows you to generate and compile the firmware in the cloud and use your smartphone to transfer and the firmware to the board. All the necessary hardware libraries are accessible through the app so you can select, download and transfer them to your LoRa device directly. The solution uses Grove connectors that allow easy and quick use of sensors, actuators or external elements without the need for soldering. Users can just connect the blocks and build their project. LoRaCatKitty supports a long list of sensor modules with Grove connectors.

The LoRaCatKitty app for Android is used to wirelessly program the device and will allow beginners to develop an infinite number of applications in an easy and intuitive way. LoRaCatKitty is completely compatible with LoRaWAN platforms like The Things Network, Beelan and others, allowing you to access RESTful API resources which can be used to develop IoT apps easily with the sensors and actuators visualized.

Technical specs of the hardware:

  •     Class A LoRaWAN Soon support of Class C LoRaWAN
  •     Wi-Fi: 802.11b/g/n Encryption
  •     Wi-Fi: WEP/TKIP/AES
  •     Module ESP8266-12E Certified FCC
  •     Module RN2903 Certified FCC
  •     Power supply:battery port: 3.4 V to 4.2 V
  •     Micro USB: 5 V
  •     Output current: 1000 mA MAX
  •     Operating voltaje : 3.3 V
  •     Charging current: 500 mA MAX
  •     Flash memory: 4 MB
  •     Size: 50 mm x 50 mm
  •     Weight: 26 g

Semtech’s LoRa Technology Enables Rural IoT Network for Farmers

Semtech has announced its collaboration with National Narrowband Network Communications (NNNCo) to build a nationwide rural IoT network to bring high-tech agriculture solutions to Australian farmers. The LoRaWAN open standard developed by the LoRa Alliance is expected to help transform Australia’s farms, giving farmers real-time data on soil moisture, rainfall, crops, water levels, and livestock through a network of in situ low-cost wireless sensors. One of the key comptabilities of a LoRaWAN is that it enables users to communicate bi-directionally with sensors on an individual or group level.

LoRa-NNNCo-PR-graphic-press

The sensors use limited power and can operate ‘in the field’ for years without the need for intervention. The farmer will be able to make intelligent, sound decisions to drive multiple functions, including irrigation, livestock feed stations, water pumps, and emergency signals. The LoRaWAN network will immediately cover one million acres of farmland across rural New South Wales (NSW) which will encompass dry land crops, horticulture and livestock and a number of rural towns. Within 18 months, the plan is to extend broadly across Australia.

Semtech’s LoRa wireless RF technology is a widely adopted long-range, low-power solution for IoT that gives telecom companies, IoT application makers and system integrators the feature set necessary to deploy low-cost, interoperable IoT networks, gateways, sensors, module products, and IoT services worldwide. IoT networks based on the LoRaWAN specification have been deployed in over 50 countries.

Semtech | www.semtech.com

Small Antenna Covers Bands for LPWAN, IoT and Smart Cities

Antenova has announce a new antenna, Grandis, part number SR42I010. It is an SMD antenna that is physically smaller yet provides enhanced performance in the 863-870 MHz and 902-928MHz bands. It directly targets the growing number of M2M and IoT applications using the LPWAN protocols. With Grandis, Antenova has reduced the footprint of the LPWAN antenna to 12.0 x 11.0 x 1.6mm, while also enhancing the antenna’s performance. Grandis is a low-profile antenna which uses a ground plane to radiate, and is designed to be placed in the corner of the PCB.

Antenova Grandis SR42I010

Antenova endeavours to give PCB designers the benefit of flexibility in the positioning of the antenna within a design, so the Grandis antenna is supplied is two versions, Left and Right, to give designers a choice of locations for the antenna on a PCB. LPWAN is an increasingly popular choice for IoT and smart city applications because it uses less power, which means that the batteries within individual devices will have an extended life. Antenova’s Grandis antenna covers the newer LPWAN standards for connected devices in IoT and smart cities: LoRa, SigFox and Weightless-P. Grandis is suitable for all applications in the 863-870 MHz and 902-928MHz bands, so it could be used in industrial, scientific and medical applications, smart metering, network devices, manufacturing automation, agricultural and environmental monitoring and consumer tracking, worldwide.

 Antenova | www.antenova-m2m.com

PW1-928 RF Data Transceiver Module

The PW1-928 RF transceiver module is intended for the reliable bidirectional transfer of digital data over distances of over 300′ in cluttered urban environments (more than half a mile in true line of sight). The module—which operates in the 902-to-928-MHz frequency band—generates a nominal 7 dBm into a 50-Ω load and achieves an outstanding RX sensitivity of –112 dBm.Lemos can 1

The module uses the industry standard LoRa direct sequence chirp spreading protocol combined with a proprietary data structure to both simplify user implementation and to significantly improve packet transmission reliability. It has a Universal Asynchronous Receiver Transmitter (UART) serial interface that can be directly connected to typical microcontrollers, RS-232 converters, or USB adaptors. The module automatically handles all radio functions resulting in a true UART-to-antenna wireless link. Configuration setup is also accessed through the UART interface.

The module is well suited for a variety of applications, including asset tracking, remote data logging, and industrial/home automation. Features:

  • True “asynchronous UART to antenna” solution
  • Direct sequence (chirp) spread spectrum
  • 9.6-kbps user payload data rate
  • Uses highly robust augmented LoRa protocol
  • Low power standby and TX-from-standby modes
  • Adjustable output power
  • User programmable address and channel-group
  • 3.3-V logic I/O
  • Digital RSSI (read via serial port)

Source: Lemos International

RF-LORA Module for the IoT

RF Solutions’s RF-LORA module is a high-performance radio module delivered in a compact 23 mm × 20 mm format. Intended for Internet of Things (IoT) applications, the RF-LORA module delivers Semtech’s LoRa technology for IoT applications.RF-LORA promo image v2 copy

The RF-LORA’s specs and features:

  • Up to 16 km, spread-spectrum communication and high interference immunity within minimum current consumption
  • Semtech SX1272 LoRa chip.
  • Built-in preamble detection
  • Available in SMT and DIL packages

Source: RF Solutions