Radionut53 (since 1998)

ANTENNA SYSTEMS

The folded dipole

The parabolic dish antenna

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The j-pole antenna

click this link too find out more about the J-POLE antenna

The dipole

Half-Wave Dipole Antenna. The half-wave dipole is a balanced resonant antenna. It produces its maximum gain for a narrow range of frequencies, normally 2 percent above and below the design frequency. Since frequency assignments are normally several megahertz apart, the operator must build a separate dipole for each assigned frequency. The length of a half-wave dipole is calculated from using the following formula:

"468 divided by the frequency in magahertz"

The inverted vee

Inverted Vee. The inverted Vee, or drooping dipole, is similar to a dipole but uses only a single center support. Like a dipole, it is used for a specific frequency and has a bandwidth of plus or minus 2 percent of design frequency. Because of the inclined sides, the inverted Vee antenna produces a combination of horizontal and vertical radiation; vertical off the ends and horizontal broadside to the antenna. All the construction factors for a dipole also apply for the inverted Vee. The inverted Vee has less gain than a dipole, but the use of only a single support could make this the preferred antenna.

The vertical antenna

Many hams can put up the big tower system and put a5-element monobander on every band at 120 feet in height to have a really big signal. Okay, a few hams can build that dream station; some of the rest of us have to settle for a more modest antenna array.

Horizontally polarized antennas such as inverted vees, horizontal dipoles and longwires can give good DX performance if they are located high above the earth, but some hams can't get the needed height and hams with small lots don't have the real estate for a full-size horizontal antenna. Fortunately, antennas can also be configured vertically and in the process can show a significant improvement in the low-angle radiation needed for DX as compared to a low horizontally configured antenna.

click here for a very informative page devoted to the vertical antenna

The quad antenna

This is called a quad loop because most people configure it as a square (quad = 4, 4 sides to a square). The quad loop measures exactly 1/4 of a wavelength on each side. As you can see, this antenna actually is a Full (1) wavelength antenna as compared to the 1/2 Wavelength driven element of the Yagi. The loop is usually made from a piece of copper wire. The Quad loop alone has 2 db of gain over the dipole antenna. So, using this as the driver element our antenna already has at least 2 more db gain over a yagi antenna with the same number of elements.

The yagi antenna

The yagi is very simple. The basic yagi consists of three elements. The middle element is an antenna you are already familiar with, the simple 1/2 wave dipole antenna. This element is generically called the "driven element". This is because this is the only element that is connected directly to the radio,the radio is feed too the driven element by what is called the "GAMMA MATCH",it actually drives the whole antenna. The other two outer elements are generically called parasitic elements. One is called the Reflector and the other one is called the director element. These elements get their name from the job they do. The reflector reflects RF energy, the director directs RF energy.

Can you identify this antenna ??

I have no information on this antenna,only that it is used at a marine hf commercial instillation,if you have any information that might be usefull,please let me know.
email me: vo1mds@hotmail.com

Can you identify this antenna ??

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Commercial antenna system

These type's of antenna towers can be viewed from many areas around the world,they are used for police,ambulance,cellphone marine,or avionic uses,chances are you have seen this antenna system before.