Overview

Tags: [|Absorbing panels], [|Agilent U2001A power sensor], [|Antenna Controller], [|Antenna under test (AUT)], [|Corner Reflector], [|Far-field], [|Free-space VSWR test], [|Lab computer], [|L-Com HG2415EG], [|Mini-Circuits SSG-4000HP signal generator], [|Monopole antenna], [|Patch antenna], [|Quiet zone], [|Radiation absorbent material], [|Roomba robot], [|Transmit antenna], [|Turntable], [|Yagi-Uda array]

Home >> Overview =OVERVIEW= This is the Overview page for the Marquette University Antenna Range Wikispace. Here, you will find introductory information to provide a brief background of the antenna range and why it is important. After viewing this page, you will know about the theory and applicability behind the antenna range that will assist in understanding its relevance to the university and how it can be a valuable resource to students, staff, and faculty.


 * ==== Contents ====
 * Background
 * What is an Antenna Range?
 * What is a Free-Space VSWR Test?
 * Transmitter
 * Receiver
 * Dish Reflector
 * Corner Reflector
 * Patch
 * Yagi-Uda Array
 * Monopole ||

Background

 * Summary
 * Antenna devices play an important role in modern life. Wireless internet, Bluetooth communication, cell phones, and radios are all using antenna technology. Although antenna radiation exists everywhere, accurately measuring the power an antenna can transmit and receive must be performed in a specialized facility. Previously, Marquette University did not have a facility where antenna measurements could be taken. The original goal of the 2012-2013 E55 senior design project was to research, design, and implement a facility in the College of Engineering at Marquette University capable of measuring the radiation of an antenna. The project has since been completed and reiterated upon by both the 2013-2014 E55 senior design team and 2015-2016 E55 senior design team. Having a facility for antenna measurements is beneficial to students by allowing them take a more hands-on approach to learning about antenna design and related technologies. For many industries, knowledge about antenna design and test-measurement facilities is valuable so there was a clear importance for Marquette to have a radiation pattern facility.
 * The project was inspired by the 2011 IEEE Antenna and Propagation Society Student Design Challenge, "Radiation Patterns on a Budget".
 * The Marquette University College of Engineering sponsored the construction of the low-budget antenna range through a student-centered learning project. During the 2012-2013 academic year, one senior design team worked on this project. Once their work was finished, Mattison LeMieux put together the original web site for the Marquette University Antenna Range. Its pages can all be found on this Wikispace on the Old Website Pages page.
 * The antenna range was improved during the 2013-2014 academic year by a second senior design team.
 * Full computer automation of each test
 * Use of a USB power sensor to measure the received power
 * Construction of an enclosure using donated absorbing materials
 * A larger space to house the facility provided by the MU College of Engineering (room 440 in Olin Engineering)
 * Improved the design and produced the following up-to-date block diagram as seen below




 * The antenna range was improved again during the 2015-2016 academic year by a third senior design team. Improvements include:
 * Design and implementation of a free-space VSWR test utilizing a Roomba robot to measure anechoic chamber quality
 * Turntable to allow for ease of use when performing tests and expanding the different types of antennas for which the antenna range can test
 * New USB signal generator to produce a wider power range and frequency range of signals for antenna testing
 * Compiled documents from all senior design groups and organized them into this Wikispace

What is an Antenna Range?



 * An antenna range is a facility that is used to test the radiation characteristics of an antenna. The entire measurement facility consists of six parts.
 * Anechoic chamber
 * Signal generator
 * Antenna positioners
 * A transmitter
 * A receiver
 * Data display and recording equipment
 * There are many different types of antenna ranges varying from far-field outdoor ranges to near-field ranges. The Marquette University Antenna Range is designed to be a small, indoor, far-field range. The testing area is a small room enclosed by anechoic material, otherwise known as an anechoic chamber. [|Anechoic material] is an absorbing material that is designed to absorb incident radio-frequency radiation.

What is a Free-Space VSWR Test?

 * The free-space voltage standing wave ratio (VSWR) test is an industry standard for evaluating the quality of anechoic chambers 1]. While this method can be used in multiple applications, our purposes focus on the use of it to obtain a quiet zone qualification. The "quiet zone" is essentially a space within the anechoic chamber of the antenna range where the reflections of electromagnetic waves being transmitted coming from anywhere but the transmit antenna are at a minimum. It is important to locate and quantify this zone, so antennas under test (AUTs) can be placed within the zone to perform a more accurate antenna characteristics test.
 * Specifically, the way the free-space VSWR test can help find the quiet zone is through the determination of the voltage standing wave ratio (VSWR). The VSWR is the ratio of the maximum and minimum amplitudes of the measured electric field within the antenna range while transmitting.
 * To physically obtain the power received values needed to calculate the VSWR, typically a probe is used to move around the inside of the anechoic chamber to measure the power received at different locations. Primarily, two scans are performed. One is the transversal scan, perpendicular to the transmit antenna, and a longitudinal scan, that is done in-line with the projected electromagnetic signal from the transmit antenna. This configuration is shown below, in a graphic from the Institute of High Frequency Technology.




 * Instead of a probe. a Roomba robot was utilized to move a pre-measured receive antenna across the range in the transversal and longitudinal directions, as shown below.




 * As an industry standard, the VSWR should be less than 2 2]. It was decided that when compared to professional anechoic chambers, the Marquette University Antenna Range's anechoic chamber can be evaluated at a VSWR less than 3. For that, it was decided that after obtaining power received measurements using the Roomba as shown below, the quiet zone was the area of the antenna range in which the VSWR was less than 3, or in other words, the fluctuations of the amplitude of the reflected electromagnetic waves was less than 3 dB.
 * The procedure for the free-space VSWR test can be found on the Tests page.
 * The results of the free-space VSWR test can be found on the Collected Data page.

**Transmitter**
 * The transmitter system utilizes the signal generator and transmit antenna in order to transmit a signal into the anechoic chamber, to be measured using a receive antenna, usually the antenna under test (AUT). The transmit antenna still in use today was procured by the 2012-2013 E55 senior design team.
 * The basic specifications are as follows:
 * The model of the transmit antenna is an L-Com HG2415EG.
 * It has an operating frequency of 2400-2500 MHz with a gain of 15 dBi.
 * It has a narrow beamwidth and bandwidth with a high gain.
 * It a directional antenna with a beamwidth of 16 degrees horizontal and 21 degrees vertical which is ideal for use in the Marquette University Antenna Range.
 * More details about the L-Com HG2415EG can be found on the Equipment page.

**Receiver**
 * The receiver system utilizes an antenna that will receive power signals from the transmit antenna, allowing them to be read by the power sensor and further processed by the lab computer. The receive antenna is usually referred to as the antenna under test (AUT), because it is used to receive signals with known characteristics with which to compare the test characteristics obtained from using it in the antenna range.
 * The Marquette University Antenna Range is a far-field range, ideal for measuring lower frequency antennas with the objective of obtaining simple pattern measurements. For that, it is important to place the receive antenna in the far-field region in order to get accurate results. In order to check this, equations (1) (2) and (3), shown below, are used.


 * Therefore, the receive antenna should be placed more than 2.67 meters away from the transmit antenna.
 * **Note:** The 2015-2016 senior design team revealed that the "quiet zone" for the anechoic chamber is between 2.17 meters and 2.30 meters from the transmit antenna, placing it outside of the far-field range. It is recommended that Dr. Richie be consulted on where the receive antenna should be placed for the purpose of testing as it may be favorable to place it in one location over the other depending on the application. A comment about this issue has been noted and can be found on the Future Work page.
 * There are many types of receive antennas available to test at the range or have been tested. To learn more about the specifications and/or collected data regarding each antenna, follow the links found below.

__**Dish Reflector**__ Specifications Collected Data

__** Corner Reflector **__ Specifications Collected Data

__** Patch **__ Specifications

__** Yagi-Uda Array **__ Collected Data

__** Monopole **__ Specifications