My portable satellite radio setup won 1st place (VHF-UHF category) in this year’s go-kit (portable equipment) contest as part of the 87th anniversary of the Philippine Amateur Radio Association. It is essentially a satellite phone with collapsible antenna which allows communication with anyone, anywhere in the Philippines and neighboring countries such as Japan, Malaysia, China, Korea, Indonesia, India, Sri Lanka, Singapore, Vietnam, Hong Kong, Taiwan, and even Australia, using only a transmit power of 5W.
The go-kit was built in April 2019 to help the STAMINA4SPACE test our country’s first amateur radio satellite DIWATA2.
In a recent test I’ve conducted with my portable satellite radio setup, I’ve successfully accessed the following satellites even at elevations of only 1 to 2° (very near the horizon!): AO-91, AO-92, IO-86, SO-50, and PO-101 (DIWATA2).
A satellite on the horizon is described to have an elevation of 0° (degree) and a satellite directly overhead has an elevation of 90°. A pass may have an elevation anywhere from 0 to 90°.
While there are many factors leading to a successful low-elevation contact, the following appears to have the greatest impact:
1. Use of a well-tuned and very directional hi-gain antenna
2. Proper pointing of antennas to satellites (use a smartphone)
3. Correct polarization of antenna elements (twist until you get the best signal)
4. Use hi-power when necessary (10W)
Have you done this test lately? How low an elevation can you access the satellites? If you want to make contact with distant stations via satellite, the only way to do that would be to access satellites when they are very low in the horizon.
My satellite antenna is a Moxon-Yagi-Uda dual band VHF-UHF antenna with a single feed point (connects directly to the radio, no duplexer needed), based on the original design of LY3LP. This allows using a full duplex radio to simultaneously transmit in one band and receive in the other. Properly tuned, this antenna has an SWR (Standing Wave Ratio) of 1.0:1 in VHF and 1.1:1 in UHF.
1. Very good RX and TX signals. Check out the logs on my QRZ page or hear the audio recording as received by this antenna in this video prepared by DV2JHA. 2. Easy to build. This antenna build is intended to be very easy to replicate. Very few tools and materials needed to build one. No special parts needed. Anyone can build it. 3. Elegant design. Because it only has one feed point, you only need one dual-band VHF-UHF radio to use this antenna (instead of using two different radios and feed points for each band, thereby eliminating the need for a duplexer). The coaxial cable from the radio connects directly to the antenna (no baluns). To maximize the full capability of this antenna, use it with a radio with full-duplex capability. 4. Easy to tune. You only need to adjust the gap between the Moxon (VHF) driven element, and the Yagi-Uda (UHF) driven element to achieve perfect SWR. If you wish to move the center frequency (the frequency with the lowest SWR), adjust the length of the driven elements. 5. Lightweight. You will begin to appreciate this once you compare it with other antenna designs. Heavy antennas are not particularly useful for hand-held satellite work. 6. Portable. With the split-boom feature, you can easily store and transport this antenna. If needed, you can always disassemble and collapse everything into a very small package. 7. Durable. This antenna design is built to last a lifetime of satellite work. 8. Low-cost. How much does a commercial satellite antenna cost? To build this antenna, I spent an equivalent of 5 USD.
This antenna has been fully tested to work with satellites such as AO-91, AO-92, SO-50, IO-86, and PO-101 (Diwata 2). To build your own satellite antenna, kindly refer to the antenna plans below.
Following the successful signal reception and decoding of the International Space Station’s (ISS) Slow Scan Television (SSTV) images, I am now eager to build a dedicated hi-gain directional antenna for satellite hunting! The first step is getting the signal to and from the radio using proper connectors.
With these new set of connectors, I can now connect the FT60 to a DIY antenna which I will be building soon!
Note: The configuration can be further simplified using a SO-239 (socket) to SMA (male) converter, but not applicable for my setup as I needed the BNC interface for my other antennas :)