No Counterpoises Antenna for the 7 MHz Band

No Counterpoises Antenna for the 7 MHz Band

Credit Line: Forum from:

www.cqham.ru

By: Vitaliy Nekrasov, RA1AFS

Problem for any vertical antenna is counterpoises that should be placed around of the antenna. However the counterpoises maybe substituted by a length of coaxial cable that is closed at the end and rounded across the radiator. Figure 1 shows design of the antenna. The antenna has DD equal to usual vertical antenna that is proved by the MMANA. Figure 2 shows simulated by MMANA DD of the vertical antenna with counterpoise made with closed coaxial cable that is placed around of the antenna radiator.

The antenna made for the 40 meter band was installed at the wall of the multistore building. Radiator with length of the 530- cm was placed on the fishing pole. Counterpoise has length of 430- cm. It was made of RG11- U coaxial cable with 0.87 shortening factor. Figure 3 shows the antenna on the wall. Figure 4 shows the round counterpoise inside of balcony. Figure 5 shows parameters of the antenna.

73! de RA1AFS

Figure 1 Vertical Antenna with Round Counterpoise from a Coaxial Cable

Figure 2 DD of the Vertical Antenna with Round Counterpoise from a Coaxial Cable

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