Improved Wheeler Cap Microstrip Antenna Efficiency Measurement Based on 3D Printing

Commonly used methods for measuring the efficiency of microstrip antennas are radiometer measurement method, Q value method, and reverberation chamber method, which is more complicated, time-consuming, repeatable low and limited accuracy. For the traditional Wheeler cap method, since the input resistance of the microstrip antenna rise steeply near the resonant frequency inside the cap, the bandwidth of the antenna efficiency measurement is narrowed, thereby affecting the accuracy of antenna efficiency measurement in a wide frequency band. This paper uses 3D printing technology to make a 136 mm × 90 mm ×68 mm Wheeler cap with both adjustable length and height of 20 mm, which improves the measurement accuracy of the efficiency of the microstrip antenna in the wide frequency band of the Wheeler cap method from 4.8 GHz to 5.6 GHz. It has the characteristics of measuring in the wide frequency band, high accuracy, high repeatability, simple and convenient, and low cost.