Most Popular Books by John Lenahan

From the author of the Shadowmagic trilogy. A world of faeries, leprechauns and dragons – and magic fueled by the blood of trees. A mystery portal to the Real World. And a pair of curious young adventurers who know they shouldn'' t step through it... ? Meet Fergal the Second, nicknamed '' two'' . Or '' Doe'' , in his own language. He can do magic. But, for the moment, he'' s forgotten where he'' s from. Or what'' s happened to his blind friend Ruby. He'' s actually from Tir na Nog, the enchanted world of Shadowmagic, where a new generation of the royal House of Duir are cheeking their parents, preparing for adulthood and itching to see the Real World for themselves – whatever the peril.

The eagerly-awaited sequel to Shadowmagic.

A Lord of the Rings for the 21st century. Only a lot shorter. And funnier. And completely different.

A Lord of the Rings for the 21st century. Only a lot shorter. And funnier. And completely different.

A Lord of the Rings for the 21st century. Only a lot shorter. And funnier. And completely different.

Antennas as Transmission Lines: Linear Antenna Analysis and Design Requiring Only Algebra and Trigonometry The models presented in this book treat antennas as transmission lines. The antenna as transmission line models in this book will help you learn about antennas in a way that does not require advanced mathematics. The chapters are arranged in sections to apply transmission line models to examples of real life antennas, which are then compared to computer software models. Some examples in this book are validated by measurement of full size physical models. Treating linear antennas as transmission lines, using trig and log functions, with some Algebra, makes it possible to calculate circuit models of feed point impedance as would be measured with an antenna analyzer or VNA (vector network analyzer). Through the use of the transmission line model, linear antennas in this book are reduced to basic AC circuit components - resistors, inductors and capacitors. The insight into antennas from using transmission line models can transform your ability to visualize, analyze and synthesize antennas to your benefit. Over the years of using and teaching this method my understanding of antennas has been improved and expanded. Yours can too using examples within the pages of this book.