A Special AHARS Lecture
Professor Mike Underhill, G3LHZ
All sorts of small
antennas – they are better than you think – Heuristics shows
Content outline of the Talk:
What is Heuristics?
Practical Demonstration of ‘MagLoop’
– to make heuristic
‘The Schopenhauer Effect’
- in any new Science? A predictable
reaction to new antennas that challenge classical
The Loop Controversy
– heuristics resolves it once
and for all time! (No, it is
not losses in the tuning capacitor – it does not get
Small Antennas are Efficient.
Heuristics demonstrates and proves this using
the ‘First Law of Thermodynamics’ =
conservation of energy and power.
Heuristic Antenna Impedance
Measurements – extracting
maximum - information for design improvement –
multiple antenna modes are measured.
Heuristic Antenna Pattern measurement
– extracting maximum
information for design improvement – separating mode
Heuristic (ground wave) propagation
measurements – reveals the
main misunderstanding that has fuelled the ‘loop
controversy’ – an olive branch?
Simple Heuristic EM theory of
radiation and reception
Discovering, Inventing and
‘Impossible’ Antennas – that are supposed not to
An introduction and brief summary of
the Crossed Field Antenna (CFA) and EH antenna
– first hand practical
The Future of small antennas?
– what does it hold? – does
During his brief visit to Adelaide
Mike has graciously agreed to present AHARS club members and
guests with an entertaining and informative talk on the
controversial subject of the real-world practical
performance of electrically small HF antennas. Examples
covered will include the tuned transmitting loop, the novel
Hairpin, the Tuned Folded Dipole, and the “Double Dustbin”
antenna. The enlightening and practical orientated
presentation will be supported by a miniVNA live demo and
will include plenty of Q&A time.
Brief Bio for Prof Mike Underhill, G3LHZ
The formal (boring) stuff:
Chairman and Research Director, Toric Ltd, UK and Principal,
Underhill Research (Scientific Research Services)
Mike’s long industry career was mostly with Philips, where
his major roles included Director of the Systems Division at
Philips Research Laboratories, Redhill, and Technical
Director at MEL, Crawley. For over 20 years, Mike has been
an advisor to the Ministry of Defence in a variety of roles,
centrally through the Defence Science Advisory Council, but
also through QinetiQ (formerly DERA) and DSTL. Mike has
also enjoyed a long academic career, and has been associated
with the University of Surrey at Guildford UK for nearly 40
has been involved in Defense Electronics (mainly HF Radio)
since 1961 and EW and Radar and IR since 1980.
His current research interests
include low phase noise in oscillators and frequency
synthesis, low jitter clocks and clock recovery, HF
transmitting loops and associated electromagnetic theory,
millimetric and satellite borne HF radar and Ionospheric
sounding. He holds about 50 patents
in these and related fields and has published about sixty
papers. He has been a Fellow of the
Royal Academy of Engineering since
The amateur radio (fun) stuff:
Mike has written on HF transmitting loop antennas for RSGB
and ARRL publications including the specially commissioned
article titled “The Truth About Loops” in the International
Antenna Collection Handbook which gave an in-depth account
of the much maligned small loop. Mike currently has a book
on the subject of small loop antennas in preparation for
imminent publication in 2008.
There has been raging debate and
technical comment on the efficacy of small loops in the
RSGB’s publication RadCom in recent years, including
Pat Hawker’s widely read column.
Leigh Turner, VK5KLT.