{"id":8047,"date":"2019-10-20T07:39:22","date_gmt":"2019-10-20T07:39:22","guid":{"rendered":"https:\/\/dronenodes.com\/?p=8047"},"modified":"2023-07-19T12:43:11","modified_gmt":"2023-07-19T12:43:11","slug":"fpv-antenna-for-drone","status":"publish","type":"post","link":"https:\/\/dronenodes.com\/fpv-antenna-for-drone\/","title":{"rendered":"FPV Antenna Fundamentals"},"content":{"rendered":"\n

Antennas are one of the easily overlooked things by FPV\u2019ers. Your car is only as good as your tires. FPV Antennas collect the video signals generated by the VTX and transmit it wirelessly where another Antenna placed on the receiver collects this video signal and process it and display it onto our goggles. All of this happens in less than 40ms, in comparison an average human takes 100-150ms (1\/10th of a second) to blink.<\/p>\n\n\n\n

FPV antennas play an integral role in having a good quality video feed, meaning to say static free and reduced noise and interference, video being displayed on our goggles.<\/p>\n\n\n\n

Even if you have a $200 Flight controller<\/a>, ESC<\/a> and an expensive VTX<\/a>, the video quality can be horrible with a cheap antenna on irrespective of the FPV camera<\/a> used.<\/p>\n\n\n\n

Not only is a good quality antenna essential but the configuration of antennas used also matters. Today we are going to do just that, find out what makes for a good FPV Antenna.<\/p>\n\n\n\n

How does an Antenna Work?<\/h2>\n\n\n\n

Before we move onto what makes a good antenna, let\u2019s take a look at how an antenna works. Anything wireless must have a transmitter antenna and a receiver antenna. Our smartphone\u2019s Wi-Fi, Bluetooth etc.., all have a transmitter antenna and a receiver antenna.<\/p>\n\n\n\n

In FPV there is no difference between a transmitter antenna and a receiver antenna. But the type used on the transmitter and the receiver matters.<\/p>\n\n\n

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Transmitter antennas receive the video signals, in our case, and convert this electrical signal into electromagnetic radiation known as radio waves<\/a>. Antenna\u2019s do the job of converting the electrical signals into electromagnetic radiation by vibrating back and forth.<\/p>\n\n\n\n

This transmitted signal is interpreted by the receiving antenna which converts the radio waves back into electrical signals. Hence the FPV antenna has a direct impact on how efficiently the video is transmitted.<\/p>\n\n\n\n

Factors to consider<\/h2>\n\n\n\n

Below listed are some of the specs to keep in mind when buying the ideal antenna for FPV<\/p>\n\n\n\n

fpv antenna types<\/h2>\n\n\n
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There are 2 major types of antenna categories- Omnidirectional and Bidirectional antenna. Though how they work is quite similar but the mode of transmission of the signal widely varies.<\/p>\n\n\n\n

Directional antennas transmit the radio waves in a very narrow beam, typically 120\u00b0 or less. So if the transmitting antenna is not in the 120\u00b0 receiving area, then the receiving antenna does not receive any signals and you lose the video feed, more like a focussed beam of flashlight.<\/p>\n\n\n\n

On the other hand, Omni directional antennas ideally transmit at 360\u00b0, meaning to say no matter where or what orientation the transmitting antenna is placed, the receiving antenna always receives part of the video signal which is sometimes enough to steer your quad out of trouble, more like a light bulb radiating in all the direction.<\/p>\n\n\n

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There are a few types of Directional Antennas- Patch Antenna, Helical Antenna to name a few. In a diversity receiver, the common rule of thumb is to equip one Directional antennas such as a Patch antenna and one Omnidirectional antenna, to get the best of both worlds.<\/p>\n\n\n\n

A Helical Antenna is mostly used for long range quads where the orientation of the transmitting antenna does not change much with respect to the receiving antenna.<\/p>\n\n\n\n

Patch antennas on the other hand are used to receive signals when the quad is in front of you and within that 120\u00b0 bandwidth.<\/p>\n\n\n\n

Types of Polarization<\/h2>\n\n\n
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Linear antennas<\/strong> transmit the waves in a single plane ie., either the horizontal or the vertical axis. They have a concentrated emission and hence have a longer range. But there\u2019s catch to this increased range, the antenna from the quad and the receiver must more or less be oriented to each other.<\/p>\n\n\n\n

If the orientation is lost, the image\/video feed is lost. They are suitable for long range setups as the orientation of the quad with respect to the receiving antennas does not change significantly.<\/p>\n\n\n\n

Circularly polarized antennas<\/strong> transmit waves in 2 planes ie.., both the horizontal and the vertical simultaneously. This results in a slight loss of the transmission power and hence a reduced range.<\/p>\n\n\n\n

We don\u2019t have to worry about the orientation as the receiver keeps receiving part of the video no matter the orientation of the quad. If you plan to race, the quad tends to keep changing its orientation rather often. Hence:<\/p>\n\n\n\n

Omnidirectional antennas<\/strong> = Exceptional image quality at close proximity flying<\/p>\n\n\n\n

Bidirectional antennas<\/strong> = Long range flying<\/p>\n\n\n\n

LHCP VS RHCP – Circular Polarization<\/h2>\n\n\n
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LHCP stands for Left hand circular polarization and RHCP stands for Right hand circular polarization. LHCP and RHCP refers to the direction the wave is rotated. If when viewed from the back, the wave is rotated to the right then the wave is Right hand circularly polarized. Likewise, if the wave is rotated to the left, the wave is known as Left hand circularly polarized.<\/p>\n\n\n

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Apart from how the wave is rotated, the antenna does not have any other difference. But as a rule of thumb, I would recommend getting a RHCP antenna for the sole reason that most pilots run RHCP antennas and spectating would be cool at an event.<\/p>\n\n\n\n

Frequency<\/h2>\n\n\n\n

Frequency is one of most important aspects to consider early on in the hunt for a suitable Antenna. Each antenna is tuned to work well with a particular range of frequencies. So a 2.4GHz antenna will not work well with a 5.8GHz setup and vice-versa.<\/p>\n\n\n\n

Also omnidirectional antennas are only available for 5.8GHz and are not available for lower frequencies such as 2.4GHz or 1.2GHz, usually used for long range FPV. Why you may ask? Long range quads usually fly 10+ Km and since the quad is so far out, the orientation of the transmitting antenna with respect to the receiving antenna is very minimal.<\/p>\n\n\n\n

Also Omnidirectional antennas are good for close to medium range and the strength of the received signals diminish greatly with increase in distance.<\/p>\n\n\n\n

Free Space Path Loss<\/h3>\n\n\n\n

Now let us get a little geeky. Beware it involves a bit of math!!!<\/p>\n\n\n\n

Free space path loss is the loss in signal strength of a signal as it travels through free space. The loss in power should be unity.<\/p>\n\n\n