1. Multiple half wave oscillators are arranged in a vertically arranged linear array
2. Add a reflective plate on one side of the linear array (taking the vertical array of two half wave oscillators with reflective plates as an example)
Gain G=11~14 dBi
To improve the gain of the planar antenna, an additional eight and a half wave oscillator array can be used
As mentioned earlier, the gain of a vertically arranged linear array of four and a half wave oscillators is approximately 8 dBi; A four element linear array with a reflector added on one side, which is a conventional planar antenna, has a gain of approximately 14-17 dBi.
An eight element linear array with an additional reflector on one side, known as an elongated plate-shaped antenna, has a gain of approximately 16-19 dBi. It goes without saying that the length of the elongated plate antenna is twice that of a conventional plate antenna, reaching about 2.4 meters.
High gain grating
From the perspective of cost-effectiveness, people often choose grid shaped parabolic antennas as the main antenna for repeaters. Due to the good focusing effect of the parabolic mask, the parabolic antenna has strong focusing ability. A grid shaped parabolic antenna with a diameter of 1.5 meters can achieve a gain of G=20dBi in the 900 megaband. It is particularly suitable for point-to-point communication, for example, it is often chosen as the donor antenna for repeaters.
The parabolic surface adopts a grid structure, firstly to reduce the weight of the antenna, and secondly to reduce wind resistance.
Parabolic antennas can generally provide a front to back ratio of no less than 30 dB, which is also a technical requirement that repeater systems must meet for anti self-excitation of receiving antennas.
Yagi directional antenna
Yagi directional antenna has advantages such as high gain, lightweight structure, easy installation, and low cost. Therefore, it is particularly suitable for point-to-point communication, such as being the preferred antenna type for outdoor receiving antennas in indoor distribution systems.
The more units the Yagi directional antenna has, the higher its gain. Usually, 6-12 units of Yagi directional antenna are used, and its gain can reach 10-15dBi.
Indoor ceiling antenna
Indoor ceiling mounted antennas must have advantages such as lightweight structure, beautiful appearance, and easy installation. The indoor ceiling mounted antennas seen in the current market have many different shapes and colors, but their core structure is almost the same. The internal structure of this ceiling mounted antenna, although small in size, is based on antenna broadband theory, aided by computer design, and debugged using a network analyzer. Therefore, it can well meet the standing wave ratio requirements in a very wide working frequency band. According to national standards, the standing wave ratio index of antennas operating in a very wide frequency band is VSWR ≤ 2. Of course, it is better to achieve a VSWR ≤ 1.5. By the way, indoor ceiling antennas belong to low gain antennas, generally G=2 dBi.
