Cardiff Microwave Roundtable


March 16, 2019

Time Event Description
9:30 Doors open
10:30 Welcome
10:40 Talk 1 Amateur Television on the Microwave Bands
11:15 Talk 2 RF Power Amplifier Design Considerations
11:50 Break Measurements, project demos, etc
12:30 Lunch Buffet at the University
13:30 Talk 3 Amateur Optical Communications
14:05 Talk 4 Advanced High Efficiency PAs
14:40 Break
15:20 Talk 5 Microwave Moonbounce Communication
15:55 Talk 6 Digital Pre-Distortion
16:30 Closing remarks ~5 minutes
17:00 Venue Closes Moving to a pub until dinner
18:30 - 21:00 Dinner

Breaks

The ENGIN Forum will be open all day and have refreshments during breaks. There are five booths currently expected, if you want to bring items to show or to sell please let us know (officers@cardiffars.org.uk).

There will be a variety of microwave test equipment setup to make measurements of attendees items. If you have any equipment you can bring, please let us know.

Instrument Range
Two port VNA 2 MHz to 6 GHz (PAs only to 2.4 GHz and 50 Watts due to available attenuators)
Frequency Counter 10 Hz to 26.5 GHz
Power Meter 10 MHz to 26.5 GHz
Noise Figure 10 MHz to 1.6 GHz (noise source to 18 GHz)
Signal Generator 100 kHz to 40 GHz (Two tone capable)
Rubidium 10 MHz reference (all devices will be locked to it)
Digital Multi Meters 8.5 digits DC & AC current and voltage, resistance - 5.5 digit capacitance

Talks

Microwave Moonbounce Communication

Peter Blair - G3LTF

The talk will briefly cover the history of this fascinating mode of radio communication from WW2 to the present. It will describe the physical factors that influence the signal path from earth to moon and back and how these are countered. Some typical amateur installations will be illustrated together with an outline of measurements and tools to assess their performance.

Digital Pre-Distortion: Introduction and use

Derek Kozel - MW0LNA

Digital Pre-Distortion is a powerful technique to reduce the distortion and loss of SNR caused by the non-linear effects of amplifiers. This talk introduces the technique and shows how it can be used with Software Defined Radios and GNU Radio.

Slides GNU Radio Files

Amateur Television on the Microwave Bands

Noel Matthews - G8GTZ

British Amateur Television Club

British Amateur Television Club

Noel will give an overview of his experiences of operating DATV on the Microwave bands from 3.4GHz to 76GHz. The talk will give an overview of the system architectures used and lessons learnt, particularly the importance of low phase LO chains when operating DATV.

Slides

RF Power Amplifier Design Considerations for Amateur Radio

Zack Costello

Modern RF power amplifier design typically involves extensive use of computer-aided design (CAD) tools, minimising the time and cost associated with prototyping. Use of RF test and measurement equipment is also an essential element of the design flow to verify performance and identify issues that may arise.

Commercial RF CAD packages and, in particular, measurement equipment are often unavailable to amateur radio operators due to both cost limitations and the necessary technical training required to effectively use these tools.

This talk will discuss PA design from an amateur radio perspective, looking at the fundamentals of PA design, the capabilities of current open-source RF CAD software, and highlighting some points of interest within the design flow.

Slides QUCS and Octave Files

Amateur Optical Communications

Barry Chambers - G8AGN

This talk outlines what equipment is required for transmitting and receiving lightwave signals, how to build effective antennas, coping with QRM, operating techniques and modes and current DX records.

Slides

Additional Info

Advanced high efficiency power amplifier architectures for modern signals

David Collins - 2E0LXD

The power amplifier is often the largest consumer of energy in a radio system. So obtaining a high efficiency from the power amplifier is often a critical design criteria, especially when the system being designed is for portable applications where; low power consumption, compact design and thermal management are key.

Designing a power amplifier for high efficiency can be challenging, especially at microwave and mm wave frequencies and where other important design criteria such as linearity and maintaining high output power have to be considered. Often this leads to trade-offs and compromises having to be made.

Doherty back in the 1930’s was the first to come up with a PA architecture that maintained high efficiency with non-constant envelope signals, in his case, MW AM broadcast transmitters. Since then modern digital modulation schemes such as OFDM and APSK (used in DVB) that have high peak to average power ratios and require high linearity have driven the research and design of high efficiency PA architectures.

This talk introduce the techniques and concepts for high efficiency power amplifier design. Some advanced PA architectures will be discussed and key design methodologies presented.