Design Analysis: The Design Of Yagi-Uda Antenna

The design of simulated antenna is shown in Fig. 3.1. As can be seen from the figure, the Yagi-Uda antenna was built on a FR4 substrate (εr = 4.4) with the thickness of 1.6 mm. The design consists of one director element, a driven element and a ground plane acting as a reflector. To enhance the gain of the antenna coupling microstrips and metal plate were placed, that focus the entire beam towards a driven dipole.

Fig. 4.1: Simulated Yagi-Uda antenna

4.3 SIMULATED RESULTS

After simulating the design different parameters of antenna are obtained such as return loss, gain, directivity, VSWR and radiation efficiency.

(a) Return loss:

Return loss is related to both standing wave ratio (SWR) and reflection coefficient (Γ). Increasing
Fig. 3.2 shows the return loss of -15.4 dB at 5.2 GHz

Fig. 4.2: Simulated Return loss of Yagi-Uda antenna

(b) Gain:

Gain of an antenna is defined as the ratio of the power radiated by the antenna from a far-field source to the power radiated by lossless isotropic antenna, which radiates equally in all the directions. It is a measure of an antenna’s ability to direct energy in a particular direction. Gain is measured in dB. Fig. 3.3 shows the gain of 7.05 dB (9.19 dBi) at 5.2 GHz.

Fig. 4.3: Simulated Gain of Yagi-Uda antenna

(c)
4.5: Simulated VSWR of Yagi-Uda antenna
(e) Bandwidth:

Bandwidth refers to the range of frequency that the antenna will radiate effectively where the antenna meets a certain set of specification performance criterion. When antenna power drops to ½ (3 dB), the upper and lower extremities of these frequency have been reached and the antenna no longer performs satisfactorily.

` An antenna that operates over a wide frequency range and still maintain satisfactory performance must have compensating circuits switched into the system to maintain impedance matching. Fig. 3.6 shows wide bandwidth of 1.8 GHz at 5.2 GHz.

Fig. 4.6: Bandwidth of Yagi-Uda antenna

(f) Radiation Efficiency

Radiation efficiency is the ratio of power radiated by antenna to the total input power supplied to the antenna as shows in Fig. 3.7.

Fig. 4.7 Simulated Radiation Efficiency of Yagi-Uda antenna

4.4 COMPARISON TABLE

Yagi-Uda antenna has been successfully designed at 5.2 GHz. It achieves better results as compare to the base paper. The bandwidth of a base paper is 400 MHz, which is quite low. Therefore bandwidth is improved by designing a new antenna by changing shape and dimension of elements. After simulating the design gain and bandwidth of 10.14 dBi and 1800 MHz are obtained respectively. Thus a high gain and broadband antenna is designed which obtained better results as compare to base paper as shows in Table