UR0GT Helical Antenna p45

ANTENTOP- 01- 2017, # 021	UR0GT Helical Antenna for the 40- meter Band
UR0GT Helical Antenna for the 40- meter Band *The publication is devoted to the memory of UR0GT.*

*Credit Line: Forum from:* www.cqham.ru	By: Nikolay Kudryavchenko, UR0GT
Nikolay (UR0GT) would like experimented with Helical Antennas for the HF Band. He already made a MMANA model of the Helical HF Antenna for the 40 meter Band. But... did not have time... he lived for us just two files of the antenna. Figure 1 shows design of the Helical Antenna for the 40- meter Band. The antenna is a typical shortened Helical Antenna with height 4.7 meter. Diameter of the antenna is 14 cm. Antenna contains 59 turns of coper wire. Nikolay, UR0GT, made two files of the antenna.	Now I play with UR0GT File of the Helical Antenna. It was very interesting for me that the MMANA confirmed some of my practical research. For example, I found on practice that the frequency of the second resonance of the Helical antenna is slighter higher the double frequency of the first resonance. MMANA gives second resonance for the antenna at 15.371 MHz that is higher the 14.100 MHz. I found on practice that the third resonance of the Helical Antenna is slighter higher the sum of the first and the second resonance of the antenna.
The two MMANA models of the UR0GT Helical Antenna for the 40- meter Band may be loaded: http: // www.antentop.org/021/helical_ur0gt_021.htm
One file for antenna wound by wire in diameter of 2- mm (12 AWG) another file for antenna wound by wire in diameter of 0.6- mm (23 AWG). Files for the Helical Antenna were simulated in MMANA. At the simulation was used parameter "Real Ground." Figure 2 shows Z of the Helical Antenna for the 40- meter Band wound by wire in diameter of 2- mm. Figure 3 shows SWR of the Helical Antenna for the 40- meter Band wound by wire in diameter of 2- mm. Figure 4 shows DD of the Helical Antenna for the 40- meter Band wound by wire in diameter of 2- mm. Antenna wound by wire in diameter of 0.6- mm shows best SWR but worst gain compare to the antenna made by 2- mm wire. The MMANA File of the Helical antenna allows to play with different ground or counterpoises, the file may be scaling for other bands and so on.. *73! Nick, UR0GT* *Note from VA3ZNW:* On my experience the input impedance and in some cases the resonant frequency of the Helical Antenna is very depend on the real ground or counterpoises used with the antenna and to the nearest objects. I experimented with Helical Antennas (in the ends 1990s- beginning 2000s) but did not simulate the antennas in MMANA. My book based on my experimenters with Helical Antennas (in Russian) is published at: http://www.antentop.org/library/shelf_helical.htm	The model has third resonance 23.078 MHz that is higher the 7.05 + 15.371= 22.421. However, anyway the high resonances depend on the antenna design and lots of different factors... *73! VA3ZNW* Figure 1 UR0GT Helical Antenna for the 40- meter Band

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UR0GT Helical Antenna for the 40- meter Band

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