IOio Antenna and the Satellites

The IOio antenna is a lightweight, dual-band (VHF/UHF) portable directional antenna designed specifically for working LEO (Low Earth Orbit) FM satellites with a Handheld Transceiver (HT). Designed by Spanish radio amateurs EA4CYQ and EB4DKA, it has become a popular homebrew alternative to commercial satellite antennas because it is incredibly cheap to build and easy to pack flat for portable operations. If you look closely at the schematic, the antenna relies on cubical quad principles—using a driven square loop and a single linear reflector for each band.

The Origin of the Name

The name “IOio” isn’t an acronym; it’s a visual representation of the antenna’s elements as they sit on the boom:

• I and O: The large VHF linear reflector (I) and the large VHF square loop radiator (O).
• i and o: The smaller UHF linear reflector (i) and the smaller UHF square loop radiator (o).

The antenna is actually an evolution of their earlier single-band 70cm design called the CJU (Canary Jail Umbrella)—named because the original prototype was built using a plastic tube taken from a canary cage and metal ribs salvaged from a broken umbrella.

Why Choose the IOio?

For LEO satellite tracking, the standard choice is often a commercial Arrow Antenna or a homebrew tape-measure Yagi. However, the IOio offers a distinct mechanical advantage: it is entirely two-dimensional.

Because a standard dual-band Arrow antenna uses crossed Yagis (elements oriented 90 degrees apart), it is bulky and takes several minutes to assemble in the field. The IOio’s loops and straight reflectors all lay flat on a single plane. You can easily slide it behind a car seat, lay it flat in a trunk, or pack it in a suitcase without taking it apart.

Here is how it stacks up against a traditional crossed-Yagi design:

Feature	IOio Antenna	Typical Crossed-Yagi (e.g., Arrow)
Element Design	Square loops & straight reflectors	Linear dipoles
Physical Profile	2-Dimensional (lays flat)	3-Dimensional (elements at 90° angles)
UHF Gain	Equivalent to a 4-element Yagi	Equivalent to a 7-element Yagi
Portability	Excellent (ready to use instantly)	Good (requires breakdown to pack flat)

While it gives up a little bit of gain compared to a longer 7-element UHF Yagi, it still provides a generous beamwidth and plenty of signal to comfortably pull the modulation out of the noise on passes from birds like SO-50 or the ISS.