This editorial sets out the theory behind the claims of some people to be able to transmit (and therefore receive) by "Poynting Vector Synthesis", and tries to show that in many instances where it is claimed that radiation exists, the power just circulates locally in loops, going nowhere. It also discusses the likely efficiency of compact antenna designs.
This editorial suggests that induced ground currents on an isolated patch of wet sand may radiate. The induction is by capacitative coupling in the case of a CFA.
This editorial presents the results of a calculation on the radiation resistance and bandwidth of the combined CFA and building structure at Tanta, in Egypt, and suggests that the induced building currents are radiating sufficiently (as a plate antenna) to account for the observed behaviour.
This editorial considers radiation from currents induced by the antenna on grounded nearby structures.
Dan Handelsman has modelled arrays of his multiple loop antenna design, and we show that they make good compact and reasonably wideband antenna structures.
In this article we introduce the concept of a "well-behaved" antenna which is not sensitive to dimensional error, and which is easy to feed over a range of frequencies, at a sensible driving point impedance.
An experiment to measure absorption through the human body around 1GHz.
This article discusses some insights into electromagnetics; the transformation from electric to magnetic field experienced by a moving observer, and general effects of relativistic behaviour implied by Maxwell's equations. It is frequently accessed at its off-journal incarnation at eryptick.net
An introduction to the SMITH chart. See also http://www.ee.surrey.ac.uk/Personal/D.Jefferies/smith.html for an extended version.
This article takes the reader through a simple stub-match example.
This is an extended version of the local page radimp.html which shows why it is that the radiation resistance of a short rod antenna rises as the square of the length, and gives examples for some short antennas.
This article considers how, using traditional accepted antenna theory, we might configure small loop antennas to get useful radiation.
This article, companion to the previous, shows that the efficiency of a compact plate antenna can be much larger than that of a similarly-sized compact antenna design made of thin wires.
This article discusses gain enhancement of antennas above a good ground, due to reflection, in the light of the method of images.
This experimental measurement report on Dan Handelsman's ADR (Asymmetric Double Rectangle) antenna design takes it to 2 GHz and shows that it has a useful bandwidth for VSWR less than 2, and considers the radiation pattern and polarisation behaviour.
This article discusses the extraordinary wide-bandwidths achievable with Dan H's Prismatic Polyhedral antennas in their 2-dimensional incarnation, and also shows that an ordinary plate dipole is very similar in behaviour for the same perimeter dimensions.
This follow-up article tries to look at the theoretical reasons why plate dipoles might be so much wider in bandwidth than their rod equivalents, and why the transition to a perimeter-only wire, to make a P2, is also effective.
This article displays photographs of a sequence of Pn antennas (P1, P2, P3, P4) and their VSWR behaviour up to 3 GHz. These antennas (alternatively pictured, 194kB) are all about 10 cm long and are (apart from the P1 which is a dipole) essentially coupled top-loaded dipole arrays. Dan Handelsman holds the patent. They (for n=2 or more) are suitable for triband mobile cell phone applications.
This article shows that the prismatic polyhedral antenna designs are significantly better performers than their close cousins, the cage dipoles.
This article reports laboratory measurements of several dielectric-loaded 2GHz ADR antennas. It is shown that some reduction in the resonant frequency occurs, up to 20-30% of the unperturbed resonance. It also adds evidence to the notion that dielectric loading of loops is far more effective than dielectric loading of straight rod antennas.
This article shows that "fat" skeleton dipoles are naturally broadband, with VSWR<2 bandwidths of an octave or more, although they are not such good performers as are the Prismatic Polyhedral antennas.
This article suggests that ground coupling does not reduce with the size of the antenna, as the antenna is made small compared to a wavelength, and that the ground effects almost entirely determine the behaviour of a compact antenna, enhancing its bandwidth, and reducing its gain from that predicted for the same antenna in free space. It is suggested that the ground effects are so strong that the exact design of the compact antenna becomes unimportant in setting its practical performance.
This article explains that antennas fed in quadrature on two ports connected by a reactance will pass power from one port to the other and may appear to be of very much lower Q factor than their radiative efficiency would indicate.
Discusses intermediate-sized loop antennas.
This introduces "controlled coupling in reduced size slow-wave structure antennas"
This reports careful measurements on loop and dipole antennas from 1 to 800 MHz, showing agreement with the NEC simulations after the room resonances and cable coupling have been suppressed using a ferrite loaded cable in a damped screened room.
This article introduces the "Plate Zagi" element, and reports closely-agreeing sims and experiments on both plate and wire Zagi elements at frequencies in the 100s of MHz.
This article investigates what happens when an antenna wire is cut at a point carrying zero conduction current.
This article describes a project to provide WiFi broadband coverage of a city from an over-flying stratospheric balloon.
This article presents measurements and simulations of one-wavelength-perimeter loop antennas close to a ground plane, at about 600MHz.
This article presents a polemic about measurements, which "ask a question of nature", and discusses the information content that can be obtained from the answer. The article is illustrated by an experiment on propagation between two 10GHz horn antennas, which gives surprisingly accurate results from rather uncertain data.
This article introduces a new slow wave structure antenna based on the Zagi and presents simulations and measurements of the performance.
This article performs a skin depth analysis of #12AWG wire dipole antennas at each HAM waveband and calculates the maximum efficiencies.
This tutorial article introduces complex impedance by means of I-V diagrams.
Antenna theory forum postings.
Some on-line theory discussion on various topics loosely related to antenna theory.
D.Jefferies 2001, 2002. 2003, 2004, 2005, 2006, 2007.
