{"id":14510,"date":"2025-06-07T16:27:29","date_gmt":"2025-06-07T10:57:29","guid":{"rendered":"https:\/\/ibexaviation.com\/pilot-training\/?p=14510"},"modified":"2026-07-26T09:51:52","modified_gmt":"2026-07-26T04:21:52","slug":"electro-magnetic-waves","status":"publish","type":"post","link":"https:\/\/ibexaviation.com\/pilot-training\/electro-magnetic-waves\/","title":{"rendered":"Electro-Magnetic Waves (EM Wave)"},"content":{"rendered":"<p> <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/radio-navigation\/r1-electro-magnetic-waves-1.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<h2>Properties of Electro-Magnetic Waves &#8211; Basics of EM Waves used in Radio Navigation<\/h2>\n<p>Electromagnetic (EM) waves are waves that carry energy from one place to another. They do not need a material medium, so they can travel through air, water, and even the vacuum of space. EM waves include radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays. They are widely used in communication, medicine, navigation, and aviation.<\/p>\n<h3>Electrical and Magnetic Field<\/h3>\n<p> <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/radio-navigation\/r1-electro-magnetic-waves-2.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<ul>\n<li>Radio aids in aviation use Electro-Magnetic (EM) Waves.<\/li>\n<li>EM waves are created by the movement of alternating current (AC) in a wire.<\/li>\n<li>Alternating current creates a magnetic field perpendicular to the electric field.<\/li>\n<li>EM radiation is transmitted through air if the wire is connected to an aerial.<\/li>\n<li>EM radiation consists of electrical and magnetic components.<\/li>\n<li>The electrical field lies in the same plane as the aerial.<\/li>\n<li>The magnetic field is perpendicular to the electrical field.<\/li>\n<\/ul>\n<h3>Electro-Magnetic Spectrum<\/h3>\n<p> <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/radio-navigation\/r1-electro-magnetic-waves-3.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<ul>\n<li>EM waves can travel through a vacuum and have a wide spectrum.<\/li>\n<li>Spectrums differ in wavelength, frequency, and energy.<\/li>\n<li>Visible light is the only part of the EM spectrum visible to the naked eye.<\/li>\n<li>X-rays have higher frequencies and shorter wavelengths.<\/li>\n<li>Long-wave audio signals have lower frequencies and longer wavelengths.<\/li>\n<\/ul>\n<h3>Short Wave and Long Wave<\/h3>\n<p> <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/radio-navigation\/r1-electro-magnetic-waves-4.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<ul>\n<li>Short waves have high levels of energy and are therefore more harmful to the body.<\/li>\n<li>EM waves travel at the speed of light in a vacuum regardless of their spectrum.<\/li>\n<li>Speed of light in a vacuum is approximately 3 \u00d7 10<sup>8<\/sup> m\/s (about 186,000 miles\/s).<\/li>\n<\/ul>\n<h2>Polarisation of Electromagnetic waves<\/h2>\n<h3>Horizontal and Vertical Polarisation<\/h3>\n<p> <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/radio-navigation\/r1-electro-magnetic-waves-5.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<ul>\n<li>Electrical and magnetic components of EM waves are perpendicular to each other.<\/li>\n<li>Polarisation is the plane of the electrical component, which carries the information.<\/li>\n<li>Vertical and horizontal aerials transmit vertically and horizontally polarised waves respectively.<\/li>\n<li>Vertically polarised waves can only be received by a vertical aerial.<\/li>\n<li>Horizontally polarised waves can only be received by a horizontal aerial.<\/li>\n<\/ul>\n<h3>Circular Polarisation<\/h3>\n<p> <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/radio-navigation\/r1-electro-magnetic-waves-6.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<ul>\n<li>Circularly polarised waves are created by a helical antenna.<\/li>\n<li>Circular polarisation can be received by various types of antennas.<\/li>\n<li>Used when polarisation changes during transmission.<\/li>\n<li>Reduces rain clutter but requires higher transmitter power.<\/li>\n<\/ul>\n<h2>Relationship between Time-Period, Wavelength and Speed of EM Waves<\/h2>\n<h3>Speed of EM Wave<\/h3>\n<p> <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/radio-navigation\/r1-electro-magnetic-waves-7.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<ul>\n<li>EM radiation is transmitted as a sinusoidal (sine) waveform.<\/li>\n<li>The frequency of the wave is the same as the alternating current producing it.<\/li>\n<li>The speed of an EM wave is equal to the speed of light.<\/li>\n<li>The speed is maximum in a vacuum.<\/li>\n<li>Radio waves travel faster over water than over land.<\/li>\n<\/ul>\n<h3>Time Period of EM Wave<\/h3>\n<p> <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/radio-navigation\/r1-electro-magnetic-waves-8.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<ul>\n<li>One cycle is one complete waveform.<\/li>\n<li>A cycle extends from the mean position to maximum, minimum, and back to the mean position.<\/li>\n<li>The time period is the time required to complete one cycle.<\/li>\n<li>Time period is usually expressed in microseconds (10<sup>-6<\/sup> seconds).<\/li>\n<\/ul>\n<h3>Frequency and Wavelength<\/h3>\n<p> <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/radio-navigation\/r1-electro-magnetic-waves-9.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<ul>\n<li>Amplitude is the maximum displacement from the mean position.<\/li>\n<li>Frequency (Hz) is the number of cycles completed each second.<\/li>\n<li>Wavelength (m) is the distance travelled during one cycle.<\/li>\n<li>Frequency and wavelength are inversely proportional.<\/li>\n<\/ul>\n<h3>Speed \u2013 Frequency \u2013 Wavelength<\/h3>\n<p> <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/radio-navigation\/r1-electro-magnetic-waves-10.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<ul>\n<li>Speed is the distance travelled by an EM wave in one second.<\/li>\n<li>Wave speed is the product of wavelength and frequency.<\/li>\n<li><strong>Speed = Wavelength \u00d7 Frequency<\/strong><\/li>\n<li>In a vacuum, the speed equals the speed of light.<\/li>\n<\/ul>\n<h3>Formula<\/h3>\n<p> <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/radio-navigation\/r1-electro-magnetic-waves-11.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<p><strong>Speed = Frequency \u00d7 Wavelength<\/strong><\/p>\n<p><strong>Frequency = Speed of Light \u00f7 Wavelength<\/strong><\/p>\n<p><strong>Wavelength = Speed of Light \u00f7 Frequency<\/strong><\/p>\n<h3>Units of Frequency Measurement<\/h3>\n<p> <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/radio-navigation\/r1-electro-magnetic-waves-12.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<ul>\n<li>1 Hertz (Hz) = 1 cycle per second.<\/li>\n<li>1 Kilohertz (kHz) = 1,000 Hz = 10<sup>3<\/sup> Hz.<\/li>\n<li>1 Megahertz (MHz) = 1,000 kHz = 10<sup>6<\/sup> Hz.<\/li>\n<li>1 Gigahertz (GHz) = 1,000 MHz = 10<sup>9<\/sup> Hz.<\/li>\n<\/ul>\n<h2>Classification of Radio Waves<\/h2>\n<h3>Radio Wave Frequency Bands<\/h3>\n<p> <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/radio-navigation\/r1-electro-magnetic-waves-13.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<table>\n<thead>\n<tr>\n<th>Band<\/th>\n<th>Frequency<\/th>\n<th>Wavelength<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>VLF<\/td>\n<td>3\u201330 kHz<\/td>\n<td>100\u201310 km<\/td>\n<\/tr>\n<tr>\n<td>LF<\/td>\n<td>30\u2013300 kHz<\/td>\n<td>10\u20131 km<\/td>\n<\/tr>\n<tr>\n<td>MF<\/td>\n<td>300\u20133000 kHz<\/td>\n<td>1000\u2013100 m<\/td>\n<\/tr>\n<tr>\n<td>HF<\/td>\n<td>3\u201330 MHz<\/td>\n<td>100\u201310 m<\/td>\n<\/tr>\n<tr>\n<td>VHF<\/td>\n<td>30\u2013300 MHz<\/td>\n<td>10\u20131 m<\/td>\n<\/tr>\n<tr>\n<td>UHF<\/td>\n<td>300\u20133000 MHz<\/td>\n<td>100\u201310 cm<\/td>\n<\/tr>\n<tr>\n<td>SHF<\/td>\n<td>3\u201330 GHz<\/td>\n<td>10\u20131 cm<\/td>\n<\/tr>\n<tr>\n<td>EHF<\/td>\n<td>30\u2013300 GHz<\/td>\n<td>10\u20131 mm<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h2>Power and Phase of Radio Waves<\/h2>\n<h3>Phase Difference Between EM Waves<\/h3>\n<p> <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/radio-navigation\/r1-electro-magnetic-waves-14.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<ul>\n<li>Phase is a defined position on a sine waveform.<\/li>\n<li>It is expressed from 0\u00b0 to 360\u00b0.<\/li>\n<li>Phase difference is the difference in phase between two waves.<\/li>\n<li>It is determined by comparing waveforms.<\/li>\n<li>Phase comparison is only possible between waves of the same frequency.<\/li>\n<li>This principle is used in some radio navigation equipment.<\/li>\n<\/ul>\n<h3>Power of Radio Wave<\/h3>\n<p> <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/radio-navigation\/r1-electro-magnetic-waves-15.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<ul>\n<li>Radio wave power decreases as distance from the transmitter increases.<\/li>\n<li>The inverse square law governs electromagnetic radiation.<\/li>\n<li>Available power is inversely proportional to the square of the distance.<\/li>\n<li>To double the range, transmitter power must be increased fourfold.<\/li>\n<\/ul>\n<h3>Polar Diagram<\/h3>\n<p> <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/radio-navigation\/r1-electro-magnetic-waves-16.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<ul>\n<li>A polar diagram joins points of equal signal strength.<\/li>\n<li>The antenna shape determines the polar diagram.<\/li>\n<li>For transmitters, it joins points receiving half the transmitted power.<\/li>\n<li>Polar diagrams are used for both transmitters and receivers.<\/li>\n<li>Receiver polar diagrams connect points receiving half the received power.<\/li>\n<\/ul>\n<h2>Attenuation &#8211; Loss of Power during Transmission<\/h2>\n<h3>Surface Attenuation<\/h3>\n<p> <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/radio-navigation\/r1-electro-magnetic-waves-17.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<ul>\n<li>Attenuation is the weakening of radio waves during transmission.<\/li>\n<li>It follows the inverse square law.<\/li>\n<li>Surface attenuation results from absorption by the Earth&#8217;s surface.<\/li>\n<li>Vertically polarised waves experience less surface attenuation.<\/li>\n<li>Horizontally polarised waves experience greater attenuation.<\/li>\n<li>Surface attenuation increases with frequency.<\/li>\n<li>Very Low Frequency (VLF) bands are used for submarine communication.<\/li>\n<\/ul>\n<h3>Factors Affecting Signals<\/h3>\n<p> <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/radio-navigation\/r1-electro-magnetic-waves-18.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<ul>\n<li>Surface attenuation is greater over land than over sea.<\/li>\n<li>Land range is proportional to three times the square root of power.<\/li>\n<li>Sea range is proportional to twice the square root of transmitter power.<\/li>\n<li>Reflection attenuation is caused by buildings and hills.<\/li>\n<li>Taller aerials reduce reflection attenuation.<\/li>\n<\/ul>\n<h3>Fading of Signals<\/h3>\n<p> <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/radio-navigation\/r1-electro-magnetic-waves-19.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<ul>\n<li>Fading causes fluctuations in signal strength.<\/li>\n<li>This is known as waxing and waning.<\/li>\n<li>Fading occurs when out-of-phase signals arrive via different paths.<\/li>\n<\/ul>\n<h3>Atmospheric Attenuation<\/h3>\n<p> <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/radio-navigation\/r1-electro-magnetic-waves-20.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<ul>\n<li>Atmospheric attenuation weakens radio waves.<\/li>\n<li>It is caused by atmospheric absorption and static interference.<\/li>\n<li>Absorption results from particles in the atmosphere.<\/li>\n<li>Higher frequencies suffer greater atmospheric absorption.<\/li>\n<li>Frequencies around 5 GHz are heavily affected.<\/li>\n<li>The wavelength at these frequencies is similar to the size of water droplets.<\/li>\n<\/ul>\n<h3>Static Interference<\/h3>\n<p> <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/radio-navigation\/r1-electro-magnetic-waves-21.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<ul>\n<li>Static interference is caused by electrical charges in the atmosphere.<\/li>\n<li>It increases during rain, thunderstorms, and solar activity.<\/li>\n<li>Lower frequencies experience greater static interference.<\/li>\n<li>Electronic circuits can also generate static noise.<\/li>\n<\/ul>\n<h3>Signal-to-Noise Ratio (SNR)<\/h3>\n<p> <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/radio-navigation\/r1-electro-magnetic-waves-22.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<ul>\n<li>SNR is the ratio of signal strength to noise, expressed in decibels (dB).<\/li>\n<li>It can be improved by increasing transmission power.<\/li>\n<li>Doubling range requires four times the transmitter power.<\/li>\n<li>Receiver sensitivity can also be improved by reducing internal noise.<\/li>\n<li>This enables reception of weaker signals.<\/li>\n<\/ul>\n<h2>Change in Direction of Radio Waves during Transmission<\/h2>\n<h3>Diffraction and Refraction<\/h3>\n<p> <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/radio-navigation\/r1-electro-magnetic-waves-23.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<ul>\n<li>Diffraction is the bending of radio waves around the Earth&#8217;s surface.<\/li>\n<li>Lower frequencies (VLF, LF, HF) experience greater diffraction.<\/li>\n<li>Refraction is the bending of waves due to changes in propagation speed caused by changes in medium density.<\/li>\n<\/ul>\n<h3>Ionospheric Refraction<\/h3>\n<p> <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/radio-navigation\/r1-electro-magnetic-waves-24.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<ul>\n<li>Occurs when radio waves slow down in the ionosphere.<\/li>\n<li>Some refracted waves return to Earth.<\/li>\n<li>Ionospheric refraction decreases as frequency increases.<\/li>\n<\/ul>\n<h3>Super Refraction<\/h3>\n<p> <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/radio-navigation\/r1-electro-magnetic-waves-25.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<ul>\n<li>Normally affects only lower frequencies.<\/li>\n<li>Special atmospheric conditions may refract higher frequencies.<\/li>\n<li>Caused by high-pressure systems.<\/li>\n<li>Also caused by warm air flowing over a cold surface.<\/li>\n<\/ul>\n<h3>Sub Refraction<\/h3>\n<p> <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/radio-navigation\/r1-electro-magnetic-waves-26.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<ul>\n<li>Caused by atmospheric conditions.<\/li>\n<li>Associated with low-pressure systems.<\/li>\n<li>Occurs when cold air flows over a warm surface.<\/li>\n<li>Super and sub-refraction can unexpectedly increase VHF range.<\/li>\n<\/ul>\n<h3>Coastal Refraction<\/h3>\n<p> <img decoding=\"async\" src=\"https:\/\/ibexaviation.com\/page-show\/radio-navigation\/r1-electro-magnetic-waves-27.jpg\" alt=\"\" loading=\"lazy\"\/><\/p>\n<ul>\n<li>Coastal refraction affects radio aids located near coastlines.<\/li>\n<li>Occurs when radio waves cross the land-sea boundary.<\/li>\n<li>Radio waves travel faster over sea than over land.<\/li>\n<li>They bend toward the slower medium (land).<\/li>\n<li>Coastal refraction is less significant at higher frequencies.<\/li>\n<li>Non-Directional Beacons (NDBs) near coastlines often use higher frequencies to minimize this effect.<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"<p>Properties of Electro-Magnetic Waves &#8211; Basics of EM Waves used in Radio Navigation Electromagnetic (EM) waves are waves that carry energy from one place to another. They do not need a material medium, so they can travel through air, water, and even the vacuum of space. EM waves include radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays. They are widely used in communication, medicine, navigation, and aviation. Electrical and Magnetic Field Radio aids in aviation use Electro-Magnetic (EM) Waves. EM waves are created by the movement of&hellip;<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"disable_featured_image":false,"footnotes":""},"categories":[326],"tags":[],"class_list":["post-14510","post","type-post","status-publish","format-standard","hentry","category-cpl-atpl-radio-navigation"],"_links":{"self":[{"href":"https:\/\/ibexaviation.com\/pilot-training\/wp-json\/wp\/v2\/posts\/14510","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/ibexaviation.com\/pilot-training\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/ibexaviation.com\/pilot-training\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/ibexaviation.com\/pilot-training\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/ibexaviation.com\/pilot-training\/wp-json\/wp\/v2\/comments?post=14510"}],"version-history":[{"count":2,"href":"https:\/\/ibexaviation.com\/pilot-training\/wp-json\/wp\/v2\/posts\/14510\/revisions"}],"predecessor-version":[{"id":16593,"href":"https:\/\/ibexaviation.com\/pilot-training\/wp-json\/wp\/v2\/posts\/14510\/revisions\/16593"}],"wp:attachment":[{"href":"https:\/\/ibexaviation.com\/pilot-training\/wp-json\/wp\/v2\/media?parent=14510"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/ibexaviation.com\/pilot-training\/wp-json\/wp\/v2\/categories?post=14510"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/ibexaviation.com\/pilot-training\/wp-json\/wp\/v2\/tags?post=14510"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}