14 Sep 2013

vertical antenna for the 144-146 MHz range with 5.6 dB gain

As is known usual vertical dipole is omnidirectional in a vertical plane. A simple antenna with omni-directional (vertical dipole) , for all its simplicity of design has a significant drawback - low gain . In order to overcome this drawback has been developed vertical collinear antenna has more gain than conventional vertical antenna with gain 5.4 dB. Image vertical antenna gain is due to the restriction pattern in the vertical plane, the radiation pattern in the horizontal plane of the antenna remains the same round. Vertical antenna with omni-directional gain 5.4 dB and its dimensions in millimeters shown in the figure. The antenna is designed to operate in the 144-146 MHz amateur band . The vertical antenna can be performed on the wooden pole or the other insulating material. Since the connection point of the power line vertical antenna has a high input resistance of about ( 500 ohm ) , you need to connect a coaxial cable to a transformer or a quarter-wave impedance transformer is made ​​of an air line with its own impedance Z = 330 ... 390 ohms. The right figure shows how to perform phasing line segments , the turns around the mast antenna diameter of 160 mm .