With the high cost of High Definition (HD) cable/Fibe TV, individuals are resorting to Over-The-Air (OTA) antennas to receive not only local channels, but also channels from the United States of America. Most TV channels operate in the UHF band (300MHz-3000MHz), and can quite easily be picked up using relatively inexpensive OTA antennas. The most popular American Networks are ABC, NBC, PBS, and Fox. The closest transmitters for these networks are located on Mount Mansfield, which is in Vermont. Of the four networks, ABC transmits the least power (10kW) and also operates in the VHF band (30MHz-300MHz), thus requiring a separate antenna.
Because of its low power, ABC presents a very difficult challenge to obtain satisfactory reception in the Montreal region. Coupled with the fact that antenna manufacturers, for the most part, only make UHF products for the consumer market, makes it almost impossible for the average person to obtain OTA reception.
As part of the experimental exercises in the “Antenna and Propagation” module of the Telecom Program, Senior Teacher, Mr. Geoffrey Alleyne, had one of his cohorts’ design and build 4 VHF Yagi antennas with a minimum of 5 elements specifically to operate at 216 MHz, which is the assigned frequency for the ABC Network channel 22. This occurred last year, and the antennas were tested first in the RF cage using Communication System Analyzers (CSAs) and then on the roof of the Centre to see if they would receive an adequate signal. While they tested quite well using the CSAs, they failed to capture channel 22, even though they were able to obtain an adequate signal from the other networks.
Mr. Alleyne attributed this to the fact that for Line of Sight (LOS), the Centre’s location is not that great and also that there is quite a lot of vegetation (tall trees) directly in the path. The antennas would have to be placed much higher on the roof. The other channels got better reception because their frequencies are approximately twice that of ABC’s, and the received signals levels were much higher, thus the antennas could capture the signals.
Recently, Mr. Alleyne had another cohort change the input connectors and modify the Gamma matching element. He then gave 2 of the antennas to student Adam Hoppenheim to test on his roof. Adam, whom Mr. Alleyne had taught in the “Semiconductors” module is a very enthusiastic student with a desire to learn, who does a lot of experimenting with electronics at home, and is very much interested in OTA television reception. Mr. Hoppenheim, who lives in Hampstead, took up the challenge and tested the two antennas on his roof in conjunction with a 10 dB gain amplifier. Unfortunately, he wasn’t able to obtain reception on one of the antennas, but with the second, he was able to get a signal at 50% and extremely good reception. The first picture below shows Mr. Hoppenheim on his roof pointing the antenna due south to obtain the best signal, while the second picture shows the actual channel on his test TV set.
Going forward, Mr. Alleyne and Adam will use the antenna that worked as a model to tune and test the remaining 2 antennas in addition to the antenna that did not work (once they have determined why it failed to function). After that, Mr. Alleyne will get future cohorts to build more antennas with additional elements resulting in more gains, and therefore better reception in areas around Montreal.
This article tells a story of just one of the opportunities available to students enrolled in the Telecom Program. For his part, Adam has this to say about his experience at PEC: “It’s been eight months since I started the Program and I’m loving everyday. I’m constantly being challenged and learning new skills, which I use on a regular basis. The teachers at PEC are extremely knowledgeable and make learning enjoyable and understandable, even to those who have no previous background in Electronics. It’s wonderful that I’m able to wake up every day and be so excited to go to school. I am very much looking forward to the next eight months.”
We at PEC strive to give our students all the tools and resources available, so that when they enter the job market they will make valuable contributions to their employers.