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1988 18th European Microwave Conference>1988>306 - 311

1. A Radial Line Slot Antenna (RLSA) is a novel planar array. This paper discusses the key design of RLSA, that is, the suppression of reflection in the antenna and the slot coupling control. Excellent performances, the antenna gain of 36.3dBi and the efficiency of 76% at 12GHz, are realized for a DBS receiving model antenna.
2. A slot antenna consists of a metal surface, usually a flat plate, with one or more holes or slots cut out. When the plate is driven as an antenna by an applied radio frequency current, the slot radiates electromagnetic waves in a way similar to a dipole antenna.The shape and size of the slot, as well as the driving frequency, determine the radiation pattern.

Radial Line Slot Antenna Structure Figure 1 shows the structure of the antenna. A Radial Line Slot Antenna is formed by a parallel plate structure, whose height is less than half a wavelength to avoid the propagation of upper modes. A radial TEM mode is generated through a coaxial probe (or. Abstract—We describe the design of a radial line slot array antenna with a shaped and focused near field. The antenna is designed in such a way to control the side lobe level and beamwidth of the normal component of the electric field with respect to the radiating aperture.

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Ando, Makoto

• Tokyo Institute of Technology, Ohokayama, Meguro-ku, Tokyo 152, Japan

Sasazawa, Hideo

• Tokyo Institute of Technology, Ohokayama, Meguro-ku, Tokyo 152, Japan

Nishikata, Satoshi

• Tokyo Institute of Technology, Ohokayama, Meguro-ku, Tokyo 152, Japan

Oshima, Yasuhide

• Tokyo Institute of Technology, Ohokayama, Meguro-ku, Tokyo 152, Japan

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The best time to put down radial wires for your amateur radio setup is early spring but it can be done other times as well. I have even done it in the fall and had good success.

The idea behind installing radial wires without digging is to let your grassy lawn grow over the radials and protect them from the mower. You don't have to trench or bury them!

First, mow the grass pretty short in the areas where you will be laying the radial wires down. Notice, I didn't say 'scalp' it—just lower the mower until the grass is about one-inch long after cutting. (Remember to readjust the height of the mower back to normal before you put it away).

Next, connect the radial wires to the radial plate with wire terminal ends and stretch them out while arraying them evenly around the antenna (that’s what 'radial' means).

Radial Wires Attached to the Radial Plate

Note: Red wires were used so they can be seen in the pictures. DX Engineering Radial Wire has a Black relaxed PVC insulation.

Some AM broadcast engineers might tell you that the radials should be as long as you can make them - up to about 1/2 wavelength. However, if you can only do 1/4-wave or 1/8-wave in certain directions then do it and don’t worry about it. They won't be resonant since they are lying on (or in) the ground. You will be surprised how much better your vertical will work. After you install a few radials and see how much better you antenna performs you will have an urge to put in more of them. Remember, laying them on the ground (or burying them) detunes them, so electrical length is relatively unimportant. Don’t resist - more is better.

Finally, starting from the antenna end of the radial wires and about every three-to-four feet, hold the wire down with a radial wire staple while pulling the radial out from the antenna to keep it taut. Push it in as far as possible to get the wire as close to the grass roots as possible. I typically use a hammer or rubber mallet to drive it home. If a radial wire is sticking up any place due to uneven ground or the wire is loose just put another anchor pin there. The idea is to get all parts of the wire down as close as possible to the ground so that the grass can grow over it.

Radial Wires held in place with Staples

Here are some pictures of what it should look like.

Two examples of radial wires installed

When you finish the last radial wire, your job is done. Mother Nature will do the rest. If you have done this in the early spring, the grass will grow up and surround the wires. The root system will also pull the radial wires down firmly along their full length. If you do it in the fall after the grass has stopped growing, it will happen the next spring. This will be done so completely that in a few weeks you will have to actively look for the radial wires to see them. Your mower will miss them completely, too. But you and your contacts will hear them right away!

73,

Slot Antenna Design

Paul, NO8D