The magnetic loop antenna wire portable CB radio

The figure below shows the magnetic loop antenna for cb band , made of copper wire with a diameter of 2 mm. The antenna has an impedance - 50 ... 75 ohms and a low reactivity. The bandwidth of the magnetic loop antenna - 600 kHz. Air condenser is mounted on a prison setting . The antenna is insensitive to the effects of human and balances. This antenna radiates in the main magnetic component of the electromagnetic wave , it can not compare in terms of field strength with a whip antenna , because the whip antenna emits electrical component of the electromagnetic wave , and measurements for the probe should be carried out on the electrical component and the frame - by the magnetic component . Were compared between the standard helical antenna cb radio and wire magnetic loop antenna was tested in the communication range . It was found that under equal distance communication using magnetic antenna was not less than 1.5 times the open area, and 2 ... 3 times larger in urban environments . In this case, a significant effect of the magnetic orientation of the antenna.

GP antenna for four bands 28, 21, 14, 7 MHz

The figure shows the antenna GP for four bands : 28 MHz , 14 MHz , 21 MHz and 7 MHz . The main antenna - mast has a height of 9.95 meters, it is usual GP antenna for a range of 7 and 21 MHz for the other two antennas GP she is still supporting mast. This antenna - mast is earthed at the connection point and the ground is connected to the counterweight to the 10.5 m long ( 7MHz ) , 5.20 m ( 14MHz ) , 3.5 m ( 21mgts ) , 2.45 m ( 28 MHz ) . and inclined at an angle of 135 degrees, so it turns out that the input impedance of the three bands GP antenna is 50 ohm, allowing you to connect without any problems to connect the coaxial cable of the same resistance. This is most effectively four band antenna operates GP is in the range of 21 MHz , as in this range for the longest antenna - 3/4L mast contains a wavelength range of the counterweights to improve alignment with the cable. In the range of 7 MHz antenna GP consistent color across a transformer in the rest of the condensers . The disadvantage of this antenna GP - is that its base should be at a height of about 7 meters (to allow the angle of 135 degrees). Advantages that the antenna can be grounded.

Wire antenna type cubic American ham

In the American Journal of QST for 1973 hobbyist WA1MKR Max Blumer was proposed antenna, which is a wire loop with a perimeter equal to the wavelength. The figure shows that the wire loop and the principle of its formation. Was based on a common loop antenna ( left panel ) , power points X and Y. This wire frame radiates vertically polarized wave in two directions perpendicular to the plane of the frame antenna A-A '. The figure shows that the center of the antenna is converted into a rectangular wire antenna , wherein the antenna radiation characteristics are not changed. In the following figure the rectangle becomes a cube . With this transformation of the perimeter wire antenna remains unchanged, but the most important thing that the length of the sides of the new antenna is transformed into a cube is reduced to a length of L/10. But unlike conventional wire- frame in this changing pattern of the antenna in the vertical plane of the antenna also radiates vertically polarized wave , but the direction of the radiation is not bi-directional and omni-directional . Author WA1MKR this antenna realized this dish with origins in the 144 MHz antenna is connected to the coaxial cable with an impedance of 50 ohms. SWR was 1.2 ... 1.4 . In the study of pattern was found that all the same it is not really a pie chart , probably because of the shielding properties of the cable and the structure. In the future, the author WA1MKR was made the same wire antenna but for the range of 21 MHz in this band , it was almost the same features except for the SWR, it is not much higher. The antenna has shown good results.

Upgraded wire antenna type inverter ranges 7 and 3.5 MHz

Not always, amateur radio is the ability to set effective long wire antenna for the 3.5 and 7 MHz . If you want to install a wire antenna type inverted V and there is no place you can upgrade this antenna a bit , reduce the size of the antenna input of the extension coil . As can be seen from the figure below size wire antenna extending spools approximately equal to the size of half-wave dipole for 7 MHz . The mast antenna has a small height, which is approximately 7 meters, the lower ends of the antenna is at a height of approximately 1.5 meters from the ground . Also from the figure that the power antenna wire modernized type inverted V through the delta transformer via a coaxial cable with an impedance of 50 ohms ... 75 . For a more exact matching transceiver must have the tuner . Since this wire antenna significantly affects the properties of the soil ( container terminal ) , then after the installation requires careful tuning . When you set up a wire antenna to watch its resonance and SWR. Changing the resonance of 100 kHz to 3.5 MHz band can occur when the length of the segment b by 5 centimeters. If you still do not get the minimum SWR you can try to change the point of connection of the delta - the transformer. With this upgrade wire antenna type inverted V, the antenna in the range of 3.5 MHz to baseband . This antenna is useful in field conditions and in areas with limited space.