TechBlog

Antennas serve as transducers between electromagnetic waves traveling in free space and guided electromagnetic signals in circuits. As such, they play a critical role in the performance of wireless communication systems. With the proliferation of mobile wireless services that deliver voice and/or data in smaller and smaller devices, the task to design an antenna for a portable unit that meets not only operational requirements but also aesthetic and packaging restrictions is becoming more and more challenging. As result, engineers rely on a combination of theory, simulation, and experimental investigation to arrive at a design that meets all the demands of a particular application.

Basic Antenna Parameters

The basic parameters of antenna are impedence, mismatch and ohmic efficiency, radiation pattern and polarization, directivity, gain and equivalent isotropically radiated power, and effective height and aperture. In addition, celebrated Friis equation is and equations for the signal to noise ratio (SNR) of an antenna and source-field relationships are also important.For a more detailed treatment of the material pointed out here, the reader is referred to “A HANDBOOK OF ANTENNA IN WIRELESS COMMUNICATION” OF CRC Press by Lal Chand Godara.

Continue reading ‘Future Antennas Will be Flat’ »

In industrial applications, a digital-to-analog (D-to-A) interface may be rather straightforward but the analog-to-digital (A-to-D) converter (ADC) can be a challenge. The capacitive input stage of both delta-sigma and successive approximation register (SAR) interfaces used for the ADC requires signal capture within a limited time frame. An improper signal chain can cause ringing and oscillation and result in inaccurate readings. However, this is just one of many factors to consider when selecting an ADC.

Signal Chain

High-performance ADCs convert the output of an analog sensor to a digital format for a microcontroller or digital signal processor. The selection of the ADC must be part of a systems approach. “When somebody starts a design, you start with the sensor, you see what kind of output impedance it has and you choose an amplifier and resistors around the amplifier and you choose that configuration based on your sensor,” says Chuck Sins, applications engineer, National Semiconductor. “Based on the accuracy of your sensor and what you are ultimately trying to achieve, then I choose the resolution of the ADC.”

Continue reading ‘Signal Conditioning Issues’ »