We started to cross emails in July 2012, and using the SPW58 he improved considerably his reception. Now, and 50 emails later, he was setting up the installation in Berlin, and the assigned building was an old Hospital (now Art Museum), with very thick walls, and with the track going into two different rooms. After studying the floor plans I recommended him a double diversity system. For each car, two receivers connected to one Oracle diversity in each room, and then both Oracles connected to a third Oracle. So total, six Oracles and eight 5.8GHz receivers for the two cars.
I then visited the installation, and helped him to fine tune the position and type of the antennas. The final setup was one HELIAXIAL58 and one SPW58 in one room, and two SPW58 in the other room.
Obviously, this installation is a multipath paradise, but the Oracles did they job pretty well. The only issue was that due to the enormous amount of multipath, they switched between channels very quickly, even with the lowest sensitivity setting, which created a slightly annoying flickering when the Oracle couldn’t synchronize the video frames properly.
Altogether, I came back from Berlin pretty satisfied with the result, and with a new friend:
Since starting with Circular Wireless, I have received technical support questions and requests for custom-built antennas from all over the world.
As some of the projects in which my support was requested are extremely interesting, I thought it was a good idea to present the most attractive ones, and write “case studies” demonstrating the real world applications of Circular Wireless antennas.
So, I will start with one of the most amazing aerial RC platform that I have ever seen: the ZipZepp.
A professional film maker who uses all kinds of aerial platforms, and a member of www.fpvlab.com , contacted me asking for some custom made antennas. Several months, PMs and emails later, I can proudly say that he is using our antennas in all his platforms, from 1.2GHz to 5.8GHz depending on the application.
The SPW58 looks really small in this huge octo… (left leg).
And of course the ZipZepp.
He was so kind that he even recorded this beautiful video. The shots of the ZipZepp from the octo are unbelievable.
And finally, just an example of what can be done combining shots from multicopters and the ZipZepp:
- In the 2011 63Km record he did not use the motor.
- With the solar panels installed on the Fascination, which in summer should be able to cover the electronics consumption on board, he has a virtually unlimited flight time (if the sun shines, of course).
- Using Yagis in the UHF transmitter RC link can easily exceed 100 km.
- In the video of his record of 2011 I noted that at 40 km he had video losses every time the plane banked to circle in a thermal, and video quality at 63Km was crap.
I concluded that the only thing limiting him to beat his own record was the video link, and I decided to contact him to explain my idea.
The configuration used for Roberto’s record of 63 Km with the Grafas was:
- Video Transmitter 1.3GHz, 1500mW.
- Standard dipole antenna in the video transmitter.
- 1.3GHz Video Receiver LawMate.
- Patch Antenna 14dB and vertical polarization in the video receiver.
Hence the possible areas for improvement were:
- Reducing the transmission power to 850MW, to reduce consumption on board.
- Change to circular polarization, to avoid losses when banking the plane as it approaches the range limits.
- Build a circularly polarized antenna for receiving with the highest possible gain, within practical limits (the size of my car …).
With this starting point we scheduled a day in Madrid to meet, see in detail his setup, and exchange ideas. It was a very nice meeting. As Roberto said when we first met: “What a pair of crazy guys!”
From there I started to work, I built a Skew Planar Wheel for the transmitter, and began to build the receiver antenna.
Obviously the first idea was “the bigger, the better,” so I bought a 100cm offset dish, along with a portable tripod, and built a feed with a 3.5-turn helical:
Subsequently I developed the helical now sold at Circular Wireless, 6.5 turns and 11.5 dBi gain, and Roberto is so happy about its performance that he hasn’t used the dish yet. I hope this summer he will keep increasing the range and end up using it!
With this configuration (SPW on the plane, transmitter 850MW, Helical of 11.5dBi on the receiver), Roberto has overcome his own record and set it to 71km, with a radically improved video quality:
2011: 63 KM, VERTICAL POLARIZATION, 1500mW
2012: 71 KM, CIRCULAR POLARIZATION, 850MW
I suspect that he will not stop here. He has actually invented a new discipline in model aircraft flying, as explained in the April issue of AEROTEC, which breaks with the classic limitations of radio controlled gliding: FPV Soaring.
Since I started in the FPV, my obsession was to improve the quality of the video signal. The immersion feeling was lost due to the momentary signal cuts, the electrical power noise, interferences from outside, and generally anything that will remind you that you were not inside the plane, but watching an image transmitted through a weak wireless link.
Among these improvements, it was clear that antennas were the key. In the same way that the best audio player in the world with a professional amplifier, is totally useless if you connect it to a low-end speakers, having a last-generation camera with the best technology of wireless video transmission, is also useless if the antennas do not have the right quality.
So, starting to develop and build my own antennas brought me to meet the team that today forms Circular Wireless: a group of Telecommunications Engineers, which brings together the passion for model airplanes and FPV, advanced knowledge of antenna design, and experience in professional production resources and laboratory testing.
We believe there is a long way to go, and our mission is to reinvest in new products development, that will enable FPV experience to become increasingly satisfactory for a growing number of pilots.
Through this blog and forums in which we participate (sircana @fpvlab @aeromodelismovirtual @rcgroups) we will publish our progress in this field, and several off-topics that we believe can entertain you.
Thank you very much for your support and Happy Flights!