DIY Satellite Antenna DU1AU

This page contains information on how to build a DIY satellite antenna. Two versions of the plan is provided: original and modified.

Moxon-Yagi Version 1: Original Moxon-Yagi Measurements
This version of the plan shows the general measurements for a Moxon-Yagi as designed by Ly3LP. Please note that since the performance of the antenna depends on the specific materials used, you may need to make slight adjustments on the measurements in order to tune the antenna to a specific frequency in VHF and UHF.

Moxon-Yagi Version 2: Modified Moxon-Yagi Measurements
This version of the plan shows the measurements of the antenna we used during the testing of Diwata 2 (PO-101) satellite, incorporating slight variation in the measurements such as changes in spacing and length of the elements, as it is optimized to work best for PO-101. This antenna also works with any other UHF-VHF satellite.

For details, please read full article below:

A satellite antenna can be made from 3 mm copper or aluminum elements, PVC boom, and some parts you may already have at home. To download the original Moxon-Yagi measurements (highest-resolution), click here.

1. All measurements are in millimeters (mm).
2. Use 3 mm copper or aluminum elements.
3. Adjust the critical gaps for lowest SWR (adjust the 14 mm and 22 mm gaps as needed).
4. Only the VHF elements (Moxon part) are connected to the feedline. The UHF element (325 mm) closest to the feedpoint is the UHF driven element. It is not connected to the feedline, but resonates only when the proper gap is achieved.
5. The feedline connects directly to the radio (no diplexer/duplexer needed).
6. Use translucent plastic insulator from an RG8 cable for the 14 mm Moxon gap
7. Use non-metallic boom (wood or orange PVC pipe).
8. The feedpoint gap is 10 mm.
9. The antenna works with any dual-band UHF-VHF radios

Here’s another version with slightly different dimensions, tuned to have lowest SWR specifically at our local satellite Diwata 2 (PO-101) frequency 145.9 MHz downlink and 437.5 MHz uplink (you may change the UHF and VHF frequencies by adjusting the critical gaps as described above). This antenna has been tested to work also with other satellites such as AO-91, AO-92, SO-50, IO-86, ISS, and PSAT2. Here’s the plan for this antenna, again, with slight variations in measurements as it is optimized for PO-101.

I’ve recently added a PTT switch on the boom, for one-hand operation. Watch the video below to see how the antenna is used in an actual satellite QSO!

Also, the Moxon elements may now be folded, making this antenna far easier to transport. Shown below are 2 versions, one using 3 mm elements, and another using 6 mm elements. The fully-collapsible antenna assembles and disassembles in just a few minutes!

For inquiries, email me at du1au@nightskyinfocus.com. To learn more about satellite communications, click here.

Related links:
Portable Satellite Radio Setup
DIY Satellite Radio Wins Go-Kit Contest

Night Sky in Focus
Astronomy and Amateur Radio
© Anthony Urbano (Manila, Philippines)

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