FPV antenna is the deciding factor that determines the range and signal strength of your FPV system. This guide will explain the basics of 5.8Ghz antennas used on mini quad VTX and VRX, and hopefully it will help you choose the best FPV antenna.
To learn more, make sure to check out our complete guide to FPV system.
Index of Content
- The Best FPV Antennas for Mini Quad
- What is FPV Antenna
- Antenna Anatomy
- Antenna Polarization – Linear or Circular
- Directional and Omni-directional Antennas
- Antenna Performance Measurements
- Types of FPV Antenna
- Considerations in Choosing Antenna for FPV
The Best FPV Antennas for Mini Quad
|Great Value Options|
|Pagoda||Foxeer 3Dbi Onmi||Aomway 4-lobe Cloverleaf|
|As mentioned previously, the pagoda is a simple yet effective design. The affordable material and easy assembly allows price to drop significantly. You can find the pagoda at around $5 to $10 each, making it one of the best value antenna out there.
There are a few different manufacturers for the Pagoda antenna, such as Lumenier, MenaceRC, Emax, Farview and Realacc.
|Foxeer makes some of the most affordable antennas in the market. Although they don’t have the best performance, they do have good enough quality for those who are on a budget to replace the stock Dipole’s. These antennas are very durable thanks to the thick plastic housing, but it also takes the total weight to a heavy 12g.||The Aomway 4-lobe’s are tried and tested antennas. They have been around for years and remain to be a good choice in terms of performance. However there is concern over robustness due to the exposed design. There is now a new version that comes with plastic caps that protects the lobes.|
|Top of the line|
|TBS Triumph||Lumenier AXII|
|Purchase on Amazon
|Purchase on Amazon
|Unlike the classic cloverleaf and skew planar wheel, the TBS Triumph does not use any bent wires in the element. The unique design provides more uniform signal coverage, makes it very durable as well as harder to clone.||The Lumenier Axii by GetFPV has a tiny diameter of only 16mm, which makes it one of the smallest and most durable CP antenna in this list. On paper it claims to have an excellent axial ratio, providing true circularity and is available in both RHCP and LHCP.|
|Cheap and worth having||Top of the line|
|Menace Invader||True RC X-Air|
|The Menace Invader is a compact directional patch antenna with a great signal reception angle, great for people with FPV goggles. It’s also very affordable too!||This is the antenna to go for if you want a high gain directional antenna, yet it gives you 120 beam-width.|
What is FPV Antenna
An antenna converts electrical power into electromagnetic waves and vice versa.
In FPV, antennas (or antennae) enable wireless communication between the video transmitter (VTX) and receiver (VRX). Antennas in your FPV system are critical elements that determine the range and signal quality.
FPV Antenna Anatomy
Every antenna consists of the same basic parts regardless design or external appearance.
- Active Element – conductive material that transfers and receives radio wave signal in the air
- Coaxial Cable – a special shielded cable that carries signal from the connector to the antenna element without emitting radio signals. They are used to extend the length of the antenna, and often are made of rigid material so it can be bent to any desired angle. Coaxial cables are not necessary if the connector is directly connected to the element
- Connector – used to connect the antenna to a video transmitter or receiver.
FPV antenna elements are made of fragile copper wires or other conductive material, therefore it’s common to see antennas come in plastic protective housing. These housing or cases do not weaken the signal and provides support for the antenna in crashes.
Antenna Polarization – Linear or Circular
Antenna polarization is a classification of FPV antennas. There are two types:
- linearly polarized antennas
- circularly polarized antennas
We explained the technical differences between Linear and Circular Polarized antennas previously.
Circular polarized (CP) antennas are the standard aftermarket upgrade for most FPV systems, because: 1. linear polarized (LP) antennas are very sensitive to multipathing interference; 2. LP antennas have to be aligned to work well. Antenna alignment is very hard to maintain on a quadcopter as it’s moving around all the time.
Multi-Pathing in FPV is when the video signal bounces off objects such as trees, walls or ground, the reflected signals become out of phase and could interfere with the main signal. Multipath interference often appears as random static in the video feed.
Therefore, for general mini quad FPV flying it’s best to use circular polarized antennas. However pilots sometime schoose linear polarized antennas because they are smaller, lighter, and more durable, although they do have worse RF performance.
LHCP and RHCP
There are two types of circular polarized antennas, “left-hand” (LHCP) or “right-hand” (RHCP). There are considerable signal loss between them, so when one pilot is using LHCP antennas and the other using RHCP, there is a smaller chance one can interfere with another’s video.
LHCP antenna rejects signal from RHCP antenna and vice versa, and interference is reduced between the two VTX’s.
For the same reason, using CP antennas helps minimize multipath interference. Every time a signal bounces off the wall or ground, it changes the direction of polarization. For example, a bounced LHCP signal becomes RHCP which will be rejected by the receiving LHCP antenna.
For pilots flying in a group, it’s best to have 1 set of each LHCP and RHCP so you can use whatever you are required when racing. If you are just flying alone most of the time, then this doesn’t really matter, just buy RHCP since it’s more widely available.
Directional and Omni-directional Antennas
Another classification of FPV antennas is directionality:
As you could guess from the names, omni-directional antennas radiate their radio waves equally in all directions, while directional antennas focus their radio waves to one direction.
One classic analogy is bulb vs torch, where the bulb is Omnidirectional and the torch is directional. If both light sources are operating at the same power, torch can reach further but in the expense of narrower beam width.
Directional antennas can be linear polarized or circularly polarized, same as omni-directional antennas.
Omnidirectional antennas are great for every-day flying, and it provides good signal coverage all around the pilot. Try to avoid using only directional antennas so you don’t have to constantly turning yourself to face directly towards your copter.
However directional antennas are often used on diversity receivers, where it can be paired with an omni-directional, or multiple directional antennas to cover all the necessary angles.
Diversity receiver can receive two signals from two antennas instead of just one, and it can then choose to display the stronger signal.
For example, if you have a diversity setup with a CP antenna and a helical antenna, the receiver will switch to the helical antenna when flying in front and to the CP antenna when flying behind.
Antenna Performance Measurements
There are many antenna performance measurements regarding FPV antenna design, such as:
- Radiation Pattern
- Axial ratio
- Frequency bandwidth – a range of working frequency
- Tuned Frequency – what frequency is the antenna tuned to and would work the best
I mainly look at the first 2 or 3 factors when choosing my antennas. As long as you are buying your equipment from a name brand you shouldn’t worry too much about it. In my opinion we are not flying a rocket for NASA and there is no need to cause headache for yourself in this case :)
But if you want to find out more about these concepts, both antenna-theory.com and wikipedia are great resources for learning about antennas. In the following sections I will try to explain what gain is and what radiation pattern can be used for.
Gain is an indicator of directional antenna’s range and angle of coverage. Higher gain generally means further range but narrower beam width. Antenna gain can alter radiation pattern as we will see in a moment.
Tutorial: How antenna gain affects range?
Radiation pattern (radiation chart) shows the shape of the radiation emitted by the antenna. These charts can tell where the weak spots are and how likely it is to lose signal.
Here are some examples to help you visualize the the signal coverage patterns.
A 0dB gain antenna is truly omni-directional that has a nearly perfect spherical radiation pattern.
However omni-directional antennas in real life usually has signal loss on the top and bottom, and the radiation pattern would look more like a doughnut in 3D. In a two-dimensional view, it forms a figure-of-eight pattern in the vertical plane, and a circle in horizontal plane.
Here is the radiation pattern for an 8dB gain patch antenna. Notice the narrow beam width in both vertical and horizontal planes.
Low DB gain might seem a bit less appealing in terms of range, but it can offer more reliable performance thanks to the more spherical radiation pattern, you can get reasonably strong signals even by pointing the antenna straight at the receiver.
In reality there is no perfect circular polarized antenna. For example, a RHCP antenna might output 90% of RHCP signal with 10% LHCP signal. So there might still be interference even if you were doing everything perfectly. And Axial Ratio is used to measure this antenna property.
In practical FPV flying terms, this is the measurement of how susceptible the antenna is to multipath interference. Antennas with better capabilities of rejecting multipathing makes it easier to fly in areas with lots of concrete and metal.
Antennas with the axial ratio closer to 1, the better.
Types of Antennas
We have covered most of the basics in FPV antenna, and now I can finally introduce you some common types of antennas used for FPV.
|Linear Polarized||Monopole, Dipole||Patch|
|Circular Polarized||Cloverleaf, Skew-Planar Wheel, Pagoda||Helical, Patch, Crosshair|
Monopole antenna is the simplest form of antenna, which is basically just a piece of un-shielded wire. It’s very common in radio receivers because they are cheap and easy to repair. However they are not as effective as Dipole antennas. The length of the exposed wire is crucial as it determines the resonant frequency (frequency that it can pick up).
Tutorial: how to make Monopole antenna.
Nearly all video transmitters and receivers come with a dipole antenna. They are light weight, and can be made very durable against crashes.
Dipole antennas has a simple design. It’s basically just a monopole antenna with a ground sleeve at under the active element. The ground sleeve can supposedly boost the performance considerably.
Cloverleaf and Skew-Planar Wheel Antennas
The cloverleaf and skew-planar wheel have been the most common antennas for mini quad FPV. Cloverleaf has 3 lobes while skew-planar wheel has four lobes.
These antennas are omni-directional like dipole. But they are circularly polarized and provide better reception and yet also less susceptible to multi-pathing, so you can fly around walls and trees with better video quality.
They are however relatively fragile therefore often come in different cases and protection. They are sometimes called “mushroom antenna” because of the shape of the housing.
Pagoda is a new antenna design that only became popular in late 2016. It’s an omnidirectional circular polarized antenna. The unique design and use of material (PCB) makes it very durable.
See our discussion on Pagoda antennas for more detail.
Helical antennas are spring-shaped, directional circular polarized antennas. The number of turns of coil determines the gain of the antenna. For more detail check out our article on Helical antenna and Patch antenna.
Patch antennas are also directional, and can be found in linear and circular polarization. They generally have less directionality than Helical, and smaller foot-print.
Considerations in Choosing Antenna for FPV
For beginners, it’s best to start with omni-directional circularly polarized antennas, for example the cloverleaf or pagoda.
Antenna performance relies heavily on decent material and precision, good antennas would therefore cost more. However some top notch antennas can cost 2 to 3 times more than the lower end ones, while they might only bring 5% or 10% range improvement.
Axial ratio is also an important factor to consider, which isn’t normally mentioned by manufacturer. But you might be able to find out their performance from reviews online.
After all, it all depends on what you can afford and your research on products.
Once you’ve invested in a diversity receiver setup, you can then look into getting some directional antennas to improve signal quality and range.
What Antennas For VTX and VRX
When buying FPV antennas in pair, normally they are interchangeable and can be used on either TX or RX. Otherwise, they should be clearly labelled “TX” and “RX” on the outside.
Antennas on VTX and VRX don’t have to be the same. Directional antennas are often used on VRX to get more range. While on the VTX you should always use omni-directional antennas, due to the fact that quadcopters can be in different orientation during flight.
Antenna Connector Types
For antenna connectors, we normally have SMA and RP-SMA. They are different in design and not compatible with each other, so make sure you buy the right one. Check this article to see the differences between SMA and RP-SMA. If you new to the hobby, try to stick with just SMA for your gear to avoid confusing yourself in the future. There is no difference in performance.
“U.FL” connectors are popular in VTX designed for racing due to the light weight and compact size for mini quad. But these are extremely fragile and have very limited mating cycles.
MMCX is a new type of connector that is being used in VTX and antennas. It’s a perfect balance between SMA and U.FL connectors in terms of weight and size. It’s much stronger than U.FL and have a lot more mating cycle. This is the my personal favorite at the moment.
A racing drone will inevitably experience many crashes during its life time. Since the antenna is installed on the outside of the frame, it will take no less abuse than the propellers and the frame. Therefore choose your antenna base on your likelihood of crashing. If you crash a lot, durability and robustness should be your priority in choosing FPV antenna.
One thing people usually overlook is the size and weight of the antenna. It’s becoming more important as mini quads are getting lighter and lighter. Every gram you save can improve the performance of your quad.
DIY FPV Antenna
Some of the antennas used in FPV actually can be made quite easily by yourself, at home. Although there is no guarantee in the performance, it’s definitely cost effective yet a fun way to learn about how antenna works :)
- My attempt at making cloverleaf antennas: https://oscarliang.com/make-diy-cloverleaf-antenna/
- Pagoda assembly video: https://www.youtube.com/watch?v=49rRR8iEiKc
- DIY Helical by IBCrazy: https://www.rcgroups.com/….Circularly-Polarized-Helical-antenna…
More to be added on a later date….
Using Linearly and Circularly Polarized Antenna Together
With all the benefits of circularly polarized antenna mentioned, we should we stick to using circular polarization at all times. But even the smallest circular polarized antennas are larger than a simple dipole antenna and typically not as robust.
Therefore it’s becoming a popular approach to use a linear polarized dipole antenna on the mini quad, and a circular polarized (RHCP or LHCP, doesn’t matter) antenna on the video receiver.
This way you still get some of the benefits of both types of antenna. Although you will be losing about 30% signal (3dB) regardless of antenna orientation. But it’s still better than the worse situation when using linear polarized antennas on both ends, where the maximum reduction in signal is 97% (30dB).
So that covers some of basics and considerations in choosing your FPV antenna, and some antenna recommendations for FPV flying. I hope this guide has helped you to choose the best FPV antenna for your mini quad!