DUBUS

DUBUS is the international bilingual, english and german, written magazine for Ham-Radio on VHF/UHF and Microwaves. The magazine is published quarterly in March, June, September and December. Each issue of over 100 pages, in A5, is devoted to a mix of state-of-the-art technical articles and DX operating news. National DUBUS representatives are in Austria, Australia, Belgium, Bulgaria, Canada, Czech Rep., Denmark, Eire, France, Finland, Greece, Italy, Japan, Netherlands, New Zealand, Norway, Portugal, Poland, Romania, Russia, Rep. of South Africa, Slovenia, Spain, Sweden, Switzerland, Ukraine, United Kingdom, USA.

DUBUS 3-2026 Vol-55

Editorial.
Single-stage PA with Motorola XRF-286 for the 23-cm band
by Hans Peter Mayer, DH1VY
While searching for a small, inexpensive RF power amplifier for the 23-cm band, I came across a build guide using Motorola XRF-286 N-channel power MOSFET. An output power of around 60W was guaranteed when using Rogers RO4003 substrate for the printed circuit board. Such a power amplifier would be perfectly suited to ... [Circuit diagram | Construction | Special Components | Commissioning and Calibration].
Terahertz Communications on 6-14 um, free space, over 4 km
by Yves Garnier, F1AVY, and Marius Cousin, F8DO
The ham radio activity allows experimentation on micrometer frequecy bands that are not yet commercially exploited. Our project aims to evaluate the potential of free-space communications in the thermal infrared, using very simple and inexpensive devices. Our initial results, obtained at frequencies around 30 THz, are presented in this report ... [Materials and Methods | Signal Processing | Modulation and Coding | Equipment | Field experimentation | Results].
How Radio Waves are Reflected in my Sitting Room
by Joachim Koppen, DF3GJ
When we take antenna measurements inside a room, we need to understand the influence of the radio waves that are reflected by the walls and interfere with the direct wave. Measurements of the power received at various places had indicated that the room is filled with a pattern of rings around the transmitter. This pattern is now modelled ... [Modelling Reflections | Computing Details | Interfering Waves | Comparison].
Aircraft Scatter: Ground Reflections & Diffraction Patterns
by Rex Moncur, VK7MO, Grant Symons, VK3ZTE, Brodie Churchill, VK3MAP and Andrew Klekociuk
Aircraft scatter produces a pronunced signal peak when an aircraft crosses the path between two stations. This peak arises from the forward-scatter diffraction lobe, which typically provides around 20 dB of gain compared with conventional radar back-scatter. Less widely appreciated is that the received signal can ... [Measurement Technique | Diffraction Formula and Patterns | 2m and 6m Tests].
Implementation of the Cold Horn Method at mm-Waves using AI
by Dimitry Fedorov, UA3AVR
The Cold Horn method is a relatively rare approach to measuring the noise figure (NF) of microwave receivers, low-noise amplifiers (LNA), and down-converters. It provides results good of accuracy down to hundredths of a dB in the microwave range. It employs a feed horn intentionally directed toward the Cold Sky, therefore the horn's noise temperature is expected to be low, up to tens of Kelvin ... [The horn | Positioning | The integration task | 76 and 86 GHz measurements | Formulas].
Digital Filter: How to calculate its mathematical Expression? Part 1
by Jean-Pierre Waymel, F5FOD
The purpose of this article is to explain how to go from an analog filter with real components to a purely digital filter, with the analog signal to be filtered having been previously converted to digital. And, of course, to verify that it works ... [Formulas | Sampling and Digitization | Practical Simulation with Excel].
Report of the K0PRT partecipation in the DUBUS/REF 2026 EME Contest
by Alex Nersesian, K6VHF
K0PRT is the call of amateur radio ststion of the Deep Space Exploration Society, a Colorado based nonprofit organization dedicated to practical astronomy and space science education for students ... [Team Operation | Performance].
Tropo Reports.
Microwave Japan.
Microwave North America.
Microwave Spain & Portugal.
Microwave Italy.
Microwave UK.
Aurora News.
News & Comments
Contest, Expeditions, Beacons update, Comments, Classified Ads.