(HP-67) Normal Mode Helical Antenna input impedance

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An extract from An Investigation of the Possible Uses of the Normal Mode Helical Antenna in the Tactical Army, Naval Postgraduate School, Master's Thesis, MAR 1978

"ABSTRACT
This paper briefly discusses the need for electrically short antennas in the combat maneuver units of the modern field army. A brief history of the work done in the field of helical antennas is presented. An approximate mathematical development is presented which describes the radiation fields of the thin normal mode helical antenna. From the radiation fields, the equations for the polarization ratio and the radiation resistance are developed. A possible design for a tactical VHF-FM antenna to cover the frequency range 30-76 MHZ is presented. The design technique is discussed in detail and a calculator program for computing the input impedance is given. The results of experimental testing are presented and recommendations for improvement are given.
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I. INTRODUCTION
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B. HISTORY AND PUSPOSE
It is the purpose of this paper to discuss the design and testing of a folded monopole helical normal mode antenna with a nominal radiation resistance and input resistance of 50 ohms. The criteria for the design are that the antenna cover the frequency range 30-76 MHZ, be no more than 24 inches in height and be self-resonant or nearly so. The rest of the paper is divided into four parts. The first part is the mathematical development which provides a basis for the development of the model. The second part is a description of the model including calculator program for the theoretical input impedance. The third is the experimental results and conclusions. The fourth is the recommendations.
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III. DESIGN METHOD FOR CONSTRUCTION
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B. HP-67 CALCULATOR PROGRAM FOR INPUT lMPEDANCE"

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