Television and Short Courses

BBC Rectenna, "Bang Goes the Theory", BBC Vision Productions, 2009

The rectenna array was developed for the BBC "Bang goes the theory" program. It was built to show the possibility of energy transmission without wires using a beam of microwave radiation.

Originally, the unit was intended to hang below a model helicopter and hover in a 2.45 GHz microwave power beam, producing 3 Amps at 7.2Vdc. However, it quickly became apparent that this was never going to work - the final rectenna was too heavy and a tethered flight was accepted. There was also the problem of the helicopter RC electronics and servos being illuminated by the high power RF field.

The power beam was produced by a magnetron from a domestic microwave oven driving a waveguide horn, producing 100 kW EIRP. The horn was designed as described in Jasik. The safe distance in the power beam was calculated as 10m at 137V/m. During experimentation, the field strength was measured continuously to ensure safety.

Even though the horn was roughly welded up from steel plate, field strength measurements in the beam showed it was producing the expected gain. Sidelobes and leakage were good.

Marconi spark gap wireless experiments, "The Spirit of Invention", BBC, 2012

I assisted in producing a demonstration of Marconi's first wireless transmission on Salisbury Plain using a spark gap transmitter and coherer made from a glass tube and metal powder.

Demonstration of power transmission using an auto-steered array

This project, for a film production company, involved a beam between two sites in Hawaii. An antenna and spectrum analyser on a helicopter measured the intensity of the beam as it crossed the profile.

Short courses

A course was produced to train antenna riggers in safety aspects of RF transmission, antenna identification and basic principles of RF propagation.