QEX: The July/August 2009 Issue
The July/August issue of QEX is coming soon, and it is full of theoretical and practical technical articles that you don't want to miss.
In this issue, Gary Steinbaugh, AF8L, presents Part 3 of "A Cybernetic Sinusoidal Synthesizer." This installment describes some limitations of proportional control systems and explains the advantages of adding integration and differentiation steps to proportional controllers. Steinbaugh also describes the construction of the RF power meter circuit used in the project
John Magliacane, KD2BD, and Bill Walker, W5GFE, describe "SPLAT!: An RF Signal Propagation and Terrain Analysis Tool." In addition to VHF/UHF line-of-sight paths, this program includes the Longley-Rice propagation model to predict path loss across irregular terrain. A Web interface provides a convenient way to use the extensive geographic terrain database in the calculations. Rudy Severns, N6LF, presents more of his research in "Experimental Determination of Ground System Performance for HF Verticals." Part 5 focuses on the effects of different numbers of radials on received signal strength for 160 meter vertical antennas.
Tom Warnagiris, K3GSY, introduces the Tapered Area Small Helix (TASH) antenna in "The Chicken Wire Wonder." Chances are, this unique broadband vertical antenna does not look like any antenna you have ever seen! An 80 meter version is 14 feet high and covers an area of about 4 × 5 feet on the ground. Maynard Wright, W6PAP, provides information on several "Alternatives to Octave" for various electronics calculations. ARRL Technical Advisor Robert J. Zavrel Jr, W7SX, presents the case for "Maximizing Radiation Resistance in Vertical Antennas" to increase the efficiency of our antennas.
John S. (Jack) Belrose, VE2CV, another ARRL Technical Advisor, presents a brief discussion "On Elevated Radials" after reading earlier installments of Rudy Severns' series about his experiments with HF vertical antenna radial systems. Ray Mack, W5IFS, continues his software defined radio column. In this installment of "SDR: Simplified," he builds an SDR that will tune a single AM broadcast band station.
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