This paper presents a printed dual band monopole antenna working below 250 MHz using meander line and an added stub. Meander line approach is used to reduce the size of the low frequency monopole. The proposed antenna is fed by microstrip line and printed on FR-4 substrate with an overall size of 290 x 83 mm2. The added stub tuned dual band operation at 114 MHz and 221 MHz with measured reflection coefficient of -19 dB at both bands. The antenna has omni-directional characteristics with efficiency greater than 90% and gain of 1.87, 1.7 dBi at both bands respectively. The antenna design is optimized through a detailed parametric study. This study includes varying stub, Meander, feed and ground dimensions. The antenna has been fabricated and measured where dual band operation in the MHz range is verified.

In this paper a band notch characteristics reconfigurable UWB leaf shape monopole antenna is reported. The proposed antenna size is 42×32×1.6 mm3 and simulated S11 -10dB impedance bandwidth is from 2.1 to 13.0 GHz. The notch bands are embodied into the designed antenna to suppress Bluetooth and WiFi bands from 2.3-2.7 GHz and 4.6-5.3 GHz. The PIN Diode is loaded to slot on the DGS to achieve notch bands. It has 4.48dB and 1.7dB gain achieved when diode ON and OFF condition. Further, it encompasses a bio-inspired leaf shape patch having high feasibility for deployment in secret and military purposes.

We designed, fabricated, and evaluated a monopole water antenna (WA) filled with pure water. A 2.4 GHz patch antenna (PA) was used for measurement comparison, and the current density distribution and 3D field strength radiation distribution and reflection coefficient of the PA had a fundamental mode and a higher-order mode at 3.5 GHz, whose polarization was 90 degrees different. The 2.4 GHz monopole WA could receive only the fundamental mode of the PA. The 3.5 GHz WA could receive the higher-order mode of the PA by rotating the WA by 90 degrees. The transmission coefficient of the 2.4 GHz WA decreased with the square of the spacing, similar to the spatial propagation characteristics of electromagnetic waves. Almost the same results could be expected if planar or three-dimensional antennas were used instead of monopole electrodes.