Testing a PCB Patch Antenna and Radiosonde QFH Antenna for Inmarsat and Iridium Reception
Over on his YouTube channel Tech Minds has been testing some antennas for Inmarsat and Iridium L-Band satellite reception. Inmarsat is a satellite service that runs on geostationary satellites, and one can be received from almost anywhere in the world. There are various services, but the ones that are easily decodable are STD-C EGC and AERO. EGC contains text information search and rescue (SAR) and coast guard messages as well as news, weather and incident reports, and AERO is a form of satellite ACARS, and typically contains short messages from aircraft.
In the first video Tech Minds tests what appears to be an as of yet unreleased prototype PCB patch antenna being designed by NooElec. The PCB patch antenna is combined with a SAWBird Inmarsat LNA and an RTL-SDR. With it he's able to receive STD-C and AERO signals.
In the second video Tech Minds tests an L-Band QFH antenna salvaged from a Vaisala weather balloon radiosonde. The QFH is designed for GPS frequencies, but can potentially be used at the slightly higher Inmarsat and Iridium frequencies. Tech Minds combines the QFH antenna with a SAWBird Inmarsat LNA, but unfortunately finds that reception is too weak for any AERO decoding to be possible. However, when used on the higher Iridium frequencies the antenna works well, and he's able to decode packets with Iridium Toolkit.
RTL-SDR Blog L-Band Patch Antenna Preview
We note that over the last several months we have been working on our own L-band patch antenna that will cover Inmarsat, GPS and Iridium frequencies all in one. We expect manufacturing to be completed near the end of the month, or early next month.
The antenna is a ceramic patch, and will come in a waterproof enclosure. It will be possible to easily mount the antenna on a window or elsewhere using the standard suction cup and bendy legs tripod included with our dipole kits. Target price is US$39.95 including the suction cup, tripod, 2M coax and shipping, but we may have it initially on sale for a lower price.
This is cheaper than buying an Inmarsat & Iridium LNA, but a bit more than the SDR-Kits patches that they brought out a few weeks ago. Although performance of our patch is much better. Keep an eye out for the initial information post coming in the next few days.
QFH & dish: please note that circular polarization is reversed on reflection, you would have to wind the QFH the other way. QFH’s pattern is also too wide to effectively feed an offset dish.
Which GPS frequencies are covered, I assume only L1 but not L5 or others, correct?
Very anxious to try the RTL-SDR Blog L-band antenna, I presume the L-band patch antenna will be bias-tee powered? Will it also be theoretically compatible with the Airspy R2?
A very good video showing how NOT to use the QFH antenna. Your coax leads should be as short as possible. You should solder the center of the coax directly to the antenna bottom and shield to the ground at the very same place.
Will it cost much more, or have other reception problems to insert a COAX long 5mt instead of 2mt? I have a gps antenna with a 5mt cable and it is really useful, specially for who uses the antenna in the car with a laptop. Thank you
We’ve left the cable on the patch purposely short, so you can connect any coax you like to the SMA port on the antenna. For lengths longer than 2-3m, i’d recommend using a cable with lower loss than RG174.