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Marquette Antenna Range



The goal of the Senior design Team E55 was to build a low-cost alternative antenna range test facility for Marquette’s College of Engineering by May 2013. This was done in order to reinforce the theoretical background of antenna design and provide practical RF (radio frequency) design and experience.

The Type of antenna range focused on in this project was a close-range indoor range in order to measure the antenna pattern of a 2.4 GHz antenna (wifi frequency). To take a pattern measurement in this set up a transmit antenna, attached to a frequency generator, sends out a signal to a receive antenna (antenna under test), the signal is received and a measurement taken using a spectrum analyzer. This measurement is recorded, then the antenna under test is rotated and another measurement taken. This continues until a full 360 degree measurement on a single horizontal plane is taken.

Throughout the 2012-2013 school year the antenna range team was able to successfully build and test a low cost antenna range. The results are shown below.

Team Members:
 * Kevin Germino
 * Michael Hintzke
 * Carissa Petzinger
 * Russell Restivo
 * Jiasheng Shi
 * Ron Vick

Team Sponsors:
 * Dr. James Richie
 * Marquette University Student-Centered Learning Program
 * LS Research

Website by:
 * Mattison LeMieux

The antenna range first test results. Note the scale for each figure is different



 Antenna Radiation Testing Facility 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:


 * 1) The Space
 * 2) Source and test Antennas (TX and RX in diagram)
 * 3) Antenna Positioners (blue and red boxes)
 * 4) A transmitter (purple boxes)
 * 5) A receiving System (orange box)
 * 6) Data display and recording equipment (grey box)

There are many different types of antenna ranges varying from far field outdoor ranges to near field ranges. The design team focussed specifically on a small indoor semi-anechoic range. This type of range is an indoor range and is set up in a room surrounded by anechoic material. [|Anechoic material] is an absorbing material that is designed to absorb incident RF radiation. This material is expensive, so the team decided to set up a semi-anechoic backdrop to the receive antenna. First a wall frame set at an angle was made. Then a layer of anechoic material was attached in order to reduce the RF reflections. This set up allowed for enough RF field to be absorbed so accurate results can be found. Also this set up allows for some mobility of the antenna range.

Transmit Side The components for the transmit side include the frequency multiplication circuit and the transmit antenna. After the frequency is doubled, the signal is sent to the transmit antenna, which in this case is a L-Com HG2415EG (right). This antenna has an operating frequency of 2400-2500 MHz with a gain of 15 dBi. Despite the large size, this antenna was chosen because it had a narrow beamwidth and bandwidth with a high gain.

 This is a directional antenna with a beamwidth of 16 degrees horizontal and 21 degrees vertical which is ideal for use in this specific antenna range.

Once the antenna was chosen, a link budget was written to make sure enough power is transmitted.



 The link budget takes into account all the loss in the system and provides a number, in dBm, that should be transmitted in order to have a readable signal. Using this number the antenna range team was able to make sure they were transmitting enough power to get good results.

Receive side

 Once the signal is transmitted it is sent to the receive antenna. The receive antenna must first be checked to make sure it is 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.



 Using this distance, 2.67 meters, the antenna range is set up. The antenna under test (AUT) chosen is an identical one to the transmit antenna for proof of concept. The final receive set up, including the pedestal and anechoic wall is shown below.



 The receive antenna is connected to a spectrum analyzer, Agilent E4402B, via coax cable. The spectrum analyzer is used to record the data of the antenna. This data is then sent to a computer. The measurement is taken at certain angles around the 360 degree horizontal plane, up to 200 points can be measured. The data collected is then compiled into a single file, and used to analyze the antenna.

<span style="color: #a7a7a7; display: block; font-family: Arial-BoldMT,Arial,sans-serif; font-size: 36px; text-align: center;">Frequency Multiplication Circuit <span style="color: #584d4d; display: block; font-family: ArialMT,Arial,sans-serif; font-size: 15px;"> The frequency generator chosen for use, the Agilent 8648B, has a frequency range of 9kHz to 2GHz. Since the frequency of operation chosen for the antenna range is 2.4GHz a multiplication circuit is needed in order to get the correct frequency. In order to multiply the signal a signal generator set at 1.2GHz is used. This is passed through a cascaded system of an amplifier, a multiplier, an amplifier, and a filter, as shown in the diagram below.



<span style="color: #584d4d; display: block; font-family: ArialMT,Arial,sans-serif; font-size: 15px;"> Using Microwave components a frequency multiplication circuit was built and tested and found to operate successfully at 2.4 GHz. The finished product is shown below.



<span style="color: #a7a7a7; display: block; font-family: Arial-BoldMT,Arial,sans-serif; font-size: 36px; text-align: center;"> Pedestal Overview <span style="color: #584d4d; display: block; font-family: ArialMT,Arial,sans-serif; font-size: 15px;"> In order for the receive antenna to be tested it must be able to rotate 360 degrees. To do this a pedestal has been designed that will rotate the antenna, pause, take a measurement, then rotate again until a full 360 picture is achieved. The pedestal consists of a stepper motor, a power supply, and a stepper drive.





<span style="color: #584d4d; display: block; font-family: ArialMT,Arial,sans-serif; font-size: 15px;"> The pedestal is controlled by the computer. A labview program was written that allows for an input telling how many steps to take and what kind of output file to produce. This program then runs though the code shown in the flowchart.

<span style="color: #584d4d; display: block; font-family: ArialMT,Arial,sans-serif; font-size: 15px;"> This program ensures that the correct number of measurements is taken and the correct data is collected. After the computer program is run, the data can be analyzed.