| ![]() | ![]() | |||||||
| |||||||||
Comments: A helpful article. (Yes, I am lazy, too.) James Gitre, Motorola 1/18/2008 3:07:30 PM Reference Guide Winner Comments: The best way to model those antennas will be to make a model of the antenna sitting on the platform (at the correct position and orientation); for example, the laptop or the mobile phone along with the correct material permittivities and permeabilities in an EM simulation software. This will give a very accurate modelling of the EM performance of the antenna without the need of having and making complex measurement test structures and also fabrication of the antenna. Depending upon the resources with the organization, this can be followed by a measurement in an anechoic chamber of the actual antenna device combination. Measuring the radiation pattern means measuring the electrical field strength of an antenna by placing another antenna at a given distance from the test antenna and revolving it around the test antenna to measure the angular variation of its electric field. Arunabh Chattopadhyay, WINMEC Reference Guide Winner Comments: Excellent article, thanks. It's important to point out that while Pi/8 is the correct and accepted Far Field region for EMag propagation in general, for some systems like phase tracking antennae used in phase measurement systems, you may have to adjust down the value for parallax to get the right range. Since Pi/8 is 22.5 phase degrees, if you are attempting to phase measure the wave down into single digits, then your range should be lengthened accordingly to give you that single digit value as opposed to Pi/8, right? Joe Luker, L-3 Communications Comments: I want to get a good idea of the measured antenna patterns. Can you describe or show us what techniques required performing the uncertainty analysis of each type antenna range? Nelson Poon, Lockheed Martin Comments: Besides the chamber, what microwave test equipment is typically needed for antenna measurements? Daniel Pils, Student Comments: I enjoyed this article from start to finish. In working on two way radio while learning RF it is always a struggle to find topics of interest this day and age below 1000 MHz. While this article is mainly for GHz applications all of the theory does apply from DC to light. Looking forward to more of these topics now that I am looking for an anechoic chamber of my own to test antenna designs I am using for GHz projects. Jason Temple, Valley Two Way Comments: Excellent explanation of near field/far field and how to tell when you've crossed from one to the other. I've seen the final equation many times, but this was a nice clear explanation of how it is derived. Textbooks should be so clear. Thanks. Ghery Pettit, Intel Corp. | Disclaimers: Responses submitted to Expert Advice are collected for sole use by Microwave Journal and www.MWJournal.com. Names and company affiliations may be published with responses according to our editorial policies. Email addresses are collected in case we need to contact you. Mailing address information submitted for the delivery of the Engineer's Handbook is collected solely for this purpose. Email addresses and mailing addresses are not published and are not shared with any third party. This form is not a magazine subscription application nor a Website registration. For magazine registration services, please click here. Individuals may continue to respond beyond the prize limit (5 total per month) but will not be eligible for receiving the complimentary Engineer's Handbook. | ||||||||
![]() |