1 00:00:01,000 --> 00:00:06,589 Welcome to CANSAT EVA! 2 00:00:11,589 --> 00:00:22,160 Let's talk about radio communications and the Jaggi antenna. 3 00:00:22,160 --> 00:00:26,160 Radio waves are all around us in our everyday life. 4 00:00:26,160 --> 00:00:30,160 But what do we mean by a radio wave? 5 00:00:30,160 --> 00:00:36,159 And how are radio waves important for your CANSAT mission? 6 00:00:36,159 --> 00:00:47,159 Lots of our day-to-day communications rely on radio waves, perhaps things you wouldn't expect, such as Wi-Fi and Bluetooth. 7 00:00:47,159 --> 00:01:02,820 Not just car radios. We will explore what exactly radio waves are and how we can use them to communicate with our concepts. 8 00:01:02,820 --> 00:01:12,819 Radio communication is sending information from one place to another using a type of electromagnetic wave, radio waves. 9 00:01:12,819 --> 00:01:27,819 As you can see here in the electromagnetic spectrum, radio waves are at the long wavelength end of the spectrum and, unlike sound, they can propagate in vacuum. 10 00:01:27,819 --> 00:01:35,700 Let's explore the radio spectrum. 11 00:01:35,700 --> 00:01:41,680 As you can see in the image, for satellite communications we use super high frequency 12 00:01:41,680 --> 00:01:53,379 bands with frequencies ranging from 2 GHz to 30 GHz and wavelength ranging from 1 cm 13 00:01:53,379 --> 00:02:03,379 to 10 cm, these waves fall within the microwave band. So radio waves of these particular frequencies 14 00:02:03,379 --> 00:02:10,719 are called microwaves. In turn, we will work in the ultra-high frequency 15 00:02:10,719 --> 00:02:23,719 event of this spectrum. We'll use either an APC220 transmitter, which works at 433MHz 16 00:02:23,719 --> 00:02:36,379 approximately or a LoRa transmitter, which works at 868MHz. XB is commonly used in IoT, 17 00:02:36,379 --> 00:02:47,500 but we will not consider it here, depending on the type of data that we want to transmit 18 00:02:47,500 --> 00:02:56,479 and the distance, we will choose a different transmitter and a different frequency. 19 00:02:56,479 --> 00:03:05,360 If you have a simple piece of data to transmit, such as a SOS signal, but over a significant 20 00:03:05,360 --> 00:03:15,860 distance a low frequency so long wavelength is perfect however broadcasting video from a 21 00:03:15,860 --> 00:03:25,219 concept to a ground station requires a much higher bit rate but over a much shorter distance so is a 22 00:03:25,219 --> 00:03:34,430 higher frequency is preferred. How does radio communication work? 23 00:03:34,430 --> 00:03:43,889 A transmitter creates an oscillating signal on a cable connected to the antenna. That signal 24 00:03:43,889 --> 00:03:51,150 is transformed and emitted as electromagnetic waves through the antenna. At the receiving 25 00:03:51,150 --> 00:03:58,909 end of the communication, part of this wave is collected and transformed back into electric 26 00:03:58,909 --> 00:04:09,389 current by another antenna. The concept project will involve two antennas. The first is the antenna 27 00:04:09,389 --> 00:04:17,709 on board the Gensat, a DAC antenna. The second is the antenna at the ground station, a Jackie antenna. 28 00:04:17,709 --> 00:04:29,600 A DAC antenna is likely the type of antenna you are most familiar with because you will 29 00:04:29,600 --> 00:04:37,639 find them on the back of your household routers or modem. 30 00:04:37,639 --> 00:04:42,819 Inside the plastic casing of a DAC antenna is a metal helix. 31 00:04:42,819 --> 00:04:48,230 This is used to receive or transmit the signal. 32 00:04:48,230 --> 00:04:53,769 Another type of antenna you would be familiar with is the jaggy antenna. 33 00:04:53,769 --> 00:05:03,470 This is the antenna that is often found connected to old-fashioned televisions and on the rooftops 34 00:05:03,470 --> 00:05:06,910 that receive analog television signals. 35 00:05:06,910 --> 00:05:14,689 Building a jaggy antenna for a concert is a good option, as it can be constructed relatively 36 00:05:14,689 --> 00:05:25,180 easily using cheap materials such as wood and copper tubes. 37 00:05:25,180 --> 00:05:33,620 Now we're gonna design our jaggy antenna using the KN9B Jaggy Antenna Calculator. 38 00:05:33,620 --> 00:05:43,120 We're gonna fix the frequency under number of elements, let's say 433 MHz for a typical 39 00:05:43,120 --> 00:05:46,779 APZ220 transmitter. 40 00:05:46,779 --> 00:05:49,500 What about the number of elements? 41 00:05:49,500 --> 00:05:55,459 One of the main factors affecting the jaggy antenna gain is the number of elements in 42 00:05:55,459 --> 00:05:56,459 the design. 43 00:05:56,459 --> 00:06:03,339 Typically, a reflector is the first element added in any jaggy design, as it gives the 44 00:06:03,339 --> 00:06:06,040 most additional gain. 45 00:06:06,040 --> 00:06:11,589 Directors are often added. 46 00:06:11,589 --> 00:06:18,250 Element spacing is another factor that must be considered. 47 00:06:18,250 --> 00:06:24,970 Spacing can have an impact on the jaggi gain, although not as much as the number of elements. 48 00:06:27,209 --> 00:06:34,089 Finally, the antenna length. When computing the optimum position for the various elements, 49 00:06:34,649 --> 00:06:42,009 it has been shown that in a multi-element jaggi array, the gain is generally proportional to the 50 00:06:42,009 --> 00:06:53,449 length of the array. With 8 elements distributed according to these lengths, we can finally 51 00:06:53,449 --> 00:07:03,129 design our jaggy antenna, with a gain of almost 11 decibels, which is a rather good value for a cancer. 52 00:07:03,129 --> 00:07:13,930 Now it's time for our jaggy antenna challenge. This is a jaggy antenna that we have in Madrid 53 00:07:13,930 --> 00:07:21,209 Science Fair. You have to put all the different parts of the antenna in order. Would you be able 54 00:07:21,209 --> 00:07:33,290 to do it? Congratulations! You've done a great job! Please continue with our atmospheric gincana 55 00:07:33,290 --> 00:07:46,649 too long to the rocket.