Dave over at FarVew.com sent these Progoda-2 antennas over to have a look at and so far I am impressed all credits go to Maarten Baert to the design of these unique antennas so lets have quick look.
Specifications
- Center frequency: 5.8 GHz
- Bandwidth: 500 MHz (5.55 – 6.05 GHz)
- Matching: S11 < -20 dB, VSWR < 1.22 (at center frequency)
- Axial ratio: < 1.3
- Radiation efficiency: 95%
So what does that all mean? Well, that’s a very good question. Taken from http://www.maartenbaert.be is a brilliant post by Maarten himself with a good comparison with the the typical omnidirectional antennas available and he goes on to show the difference in radiation and axial ratio of both types of antennas in these following graphs
So from the graphs above we can see that the Farvew Progoda-2 falls into second play in pretty much most of the stats. The antenna has been designed as an excellent all-rounder. It doesn’t win any categories, but in my eyes that is not a bad thing – there’s a lot of trade-offs with antennas, most of which is outside of my knowledge (with gain and axial ratio), but the size and durability are easy ones to comprehend and we can see later that it is both small and durable – both very important points.
As for the cost, that is a very very good price of 14.99USD for a good quality set of antennas whose stats perform so highly compared to your average antenna as seen in the below graphs
. Anyone in the hobby will know of VAS make fantastic performing antennas, but on some designs they can set you back a good amount of money. But I’ve always been a believer in you get what you pay for, so we shall see how these stand up to my VAS counterparts such as the TBS Triumph.
The Design
So this antenna differs from your usual Circular Polarized, in the fact that it is based off of a PCB antenna which until Maarten Baert designed was not known in the FPV world. You can have a search on google for the design or click this LINK to find out all the details you may need on these Progoda antennas but basically The Progoda design completely does away with the delicate cloverleaf, and replaces it with three circular circuit boards or also known as PCB boards. These three PCBs (diameter of pagodas is 22mm) are soldered to the coaxial cable, at specific distances, which creates an antenna that is durable, very easy for anyone to assemble without the worry of bending wires and cutting them to specific specs, and inexpensive,So that is three PCB plates in a stack on top of one another at precise distances in which the top two having copper traces circling around in all sorts of patterns for than full 360 degree coverage(as you can see I do not have the right terminology!!)but from precise tests from Maarten Baert he came to the final design that outperformed the ever famous TBS triumph in terms of radiation pattern which has the efficiency pattern that is 95% while the Triumph is only 90% efficient and axial ratio of 1.3 vs the TBS triumphs 0.74.
Below are picture’s of the omnidirectional PCB and it’s precise distance’s between the PCB boards.
The pagoda design completely does away with the delicate cloverleaf, and replaces it with three circular circuit boards. These three PCBs (diameter of pagodas is 22mm) are soldered to the coaxial cable, at specific distances, which creates an antenna that is durable, very easy for anyone to assemble without the worry of bending wires and cutting them to sub-millimeter specs, and inexpensive.
FarVew.com has 3d printed housings availble to buy but also provides the STL file free if you have a printer to download and make them yourself. If you wanted to make them more impact proof i would recommend getting one of these covers and even if you do break the PCB boards they are available to buy from FarVew as well,Oh did i mention you can build these antenna’s yourself?Yes that’s correct as FarVew sell what they call ”Maker Kits” which comes with everything you need to build these at home even if you have little to no soldering experience, the jig you can get to help you build makes the whole process much easier as it helps with the precise distances between each of the PCB’s that is needed these kits and antennas are available in both LHCP and RHCP ,If your soldering skills are on point you can knock out two of these in 30 minutes.
A note from Dave on this product
“Also as a note the jig is practically a must, but we include one for free if 3 kits are purchased, we also have the design files available for those that have the equipment to make them for them selves.
We have tried to price the kits to a point where if you were to get all the things your self it would be the same price, we just really like the work that Maarten has done and want as many as possible to try them out!“
Here the images of the 3d printed case,maker jig.and the LHCP and RHCP antennas.
One of the guys over on FPV-Scotland and Propnuts.co.uk gave me permission to show he’s experience with this Progoda antenna at a indoor venue they call The Depot Which as you can see from the below video it has a lot of things in the way that will hamper the Signal but from Kieren’s own words I’ve been using the Pagoda antennas since visiting The Drone Show in Birmingham last December where I picked the MenaceRC Pagoda Antennas and Patch. The PropNuts team go to indoor spot is called “The Depot” it’s an indoor Airsoft warehouse that’s full of Metal, Concrete and everything else in-between. The Pagoda style antennas seem to work really well in here paired with a Tramp HV on 100mw, it is without a doubt the best setup I’ve used. As for the durability Im using the Menace RC version which are identical to FarVews and both companies are official distributors of the Pagoda antennas and the thick plastic round the PCB’s have withstood the test of time as you can see from the indoor footage, it can get rough. The only thing I would do is add foam glue in-between the disks for extra durability
From here on this is all Maarten Beart’s work that you can check from the above link.
Originally the radiation efficiency was listed as 92%, this was a mistake. These values are based on simulation, actual measurements are below (they are very similar). The center frequency may shift a bit between batches as a result of variations in the dielectric constant of FR4. Also, not all brands of FR4 have the same dielectric constant. Frequency shifts up to 100 MHz are normal.
For comparison, here’s a simulation of the traditional cloverleaf antenna using the same simulation software and setup:
The ‘best case’ and ‘worst case’ correspond to different assumptions about what happens to signals that travel along the outside of the coax. In the ‘best case’ simulation, these are completely absorbed at the other end of the coax. In the ‘worst case’ simulation, they are completely reflected back towards the antenna. The latter case usually results in standing waves on the outside of the coax, which causes the coax itself to radiate and interfere with the radiation pattern of the antenna. This is why the radiation pattern isn’t smooth anymore. The reality will be somewhere between these two extremes.
Measurements
This gives you an idea of the kind of variations you can expect for hand-assembled antennas. The center frequency is a bit off but not enough to cause any problems. This is most likely caused by variations in the FR4 material used by the manufacturer.
Assembly
The PCBs need to be spaced accurately to get good results. The correct spacing is shown in this image:
Ideally you need to get these distances right within a 0.1 mm tolerance. The best way to do this is with an assembly jig. I used a jig which I cut out of 3.0 mm MDF with a laser cutter. You can find it in the design files. Always check whether the DXF file is loaded properly by the laser cutter software before you run it, because the DXF export feature in Inkscape is somewhat buggy. Some laser cutters act as printers, in this case it’s much more reliable to just ‘print’ the SVG from Inkscape directly.
Cut out two copies, because these parts aren’t very strong so you want to have some spare ones (and MDF is very cheap). If you can’t get access to a laser cutter, there are some online services that can make these for you, but I have no experience with those. If that’s also not an option, you can also try to get the correct spacing by stacking pieces of wood and paper until you get the correct thickness. You can actually get half-decent accuracy with this method if you measure the thickness with a caliper, but it’s not a convenient assembly method. I assembled my first two prototypes like this, it took me at least twice as long as with the assembly jig, and the accuracy was obviously not as good.
The top PCB should have the text facing up, the other two PCBs should have the text facing down. Check my photo if you aren’t sure you are doing it right. The top and middle PCB should be aligned using the alignment markers (the three little silkscreen lines that are printed on both sides), otherwise the antenna will not work at all. You can align them easily by rotating the PCBs until the markers are aligned with the edges of the arms of the assembly jig.
A temperature-controlled soldering iron is recommended. Set the temperature to 400 °C, because you need to solder directly to the coax which tends to act as a heat sink. Even with a high temperature it will take some time to heat up the coax, so just be patient. If you don’t wait long enough for the coax to heat up, you won’t get a decent solder joint. Give the solder enough time to flow into the gap between the PCB and the coax, and rotate the antenna so you can apply heat and solder from all sides. Try to use no more solder than necessary, because excess solder will shift the center frequency of the antenna.
Where to buy?
You can purchase these on farvew.com and I do highly recommend these and these will be my new go to antennas.
Feel-FPV 