Radio Frequency (RF) & Wireless Design

There was a request a few weeks back for a 6-leaf 'cloverleaf' style of antenna for First Person Video (FPV) drones and I am looking at making some more antenna models for the grabcad community, but I thought that it would be a good idea to present all the choices that there are for drone antennas.

These are some of the antenna types that I have seen sold for drones; whether they are good design choices is probably as subjective as your need and cost expectations :

1. monopole
2. dipole
3. folded dipole
4. circular
5. cloverleaf
6. patch
7. cross-hair
8. circular / spiral

The situation with most of these antennas is that most are polarized in on direction or they are omni-directional with very little gain. This may or may not be an issue depending on how far you want to transmit and how good both your transmitter and receivers are.

For high gain and longer distances a highly directional antenna will be required such as :

1. yagi array
2. quad or cubical quad
3. parabolic dish
4. horn waveguide

Here are some article links that discuss the choices for simple low cost and short range antennas :

https://www.propwashed.com/understanding-antennas/

https://www.dronetrest.com/t/the-complete-guide-to-fpv-antennas-for-your-drone/1473

https://www.rchelicopterfun.com/fpv-antennas.html

however when choosing antenna there is a lot of marketing hype and claims without the test data. So it makes sense that you get the electrical and electro-magnetic radiation specifications *before* you buy , since without it you will not know what you are buying.

The specifications should include this data :

• operating center frequency
• operational bandwidth
• power dissipation
• directional gain (dB or dBi)
• magnetic field polarization
• horizontal radiation pattern
• vertical radiation pattern
• connector types
• coax type / loss

This is in addition to the typical data such as

• mechanical dimensions
• assembled flying weight
• environmental capability
• construction materials
• coax length

One other thing to keep in mind is that lower frequencies typically are better for longer distances for the same output power due to their wavelength. But the flip size is that they are larger and will be heavier.

Most people will trade off weight for distance, but can make up for it with output power and receiver sensitivity and receiver selectivity.

The antenna directionality and the antenna gain will bridge the gap for what's lacking along with other considerations such as path loss in long distances.

Finally tracking systems are the ultimate in maximizing the gain of the antenna and the overall system performance.

All of this should be thought of before choosing your next antenna or you might find your system performance lacking, especially when you need it most.