Abstract
This paper proposes a method of constructing a log-periodic microstrip antenna. Log-periodic technique is considered to be useful to improve the characteristics of a microstrip antenna (MSA) which is narrow band in nature, without preventing the advantage of low-profile and light weight. The radiaiting elements are co-ax fed and arranged on one side of the common feed line behind the ground plane. This way of arrangement necessarily decreases the element spacings, and increases the mutual coupling between elements. The coupling effect has acted to fill up the inactive frequency regions. Larger coupling between elements due to the necessarily dense arrangement gives advantage in obtaining wide-band frequency characteristics. An example of 5 elements case proves that the present method is useful giving gain of 6 to 10 dBi over about 20%, bandwidth.
