A Low-Profile Antenna With Omnidirectional and Unidirectional Radiation Patterns Over Two Operation Bands

Abstract

A compact low-profile dual-band antenna with a single circular radiation patch is presented. The circular radiation patch is top-loaded by a metal strip, leading to a zeroth-order resonant (ZOR) mode with monopole-like radiation pattern at the lower operation band, and the ZOR mode is not affected by the position change of the probe feed. Thereby an off-center probe feed can be used to excite a TM 01 mode with patch-like radiation pattern at the upper operation band, and its performance remains good stability when the size of the metal strip is varying. The equivalent circuit, electric field and current distributions of the proposed antenna are studied to investigate the principles of the ZOR and the TM 01 modes, and all the results show that the two operation bands can be effectively and independently controlled. As a proof-ofconcept, a circular patch antenna prototype with low profile of about 0.023 λ 0 at 2.35 GHz is fabricated and tested. Good agreements between the measured and simulated results are achieved, showing monopole-like and patch-like radiation patterns within 2.28-2.40 GHz and 3.30-3.60 GHz, respectively, and the average realized gains are about 2.5 dBi and 8.5 dBi for the two operation bands. INDEX TERMS Antenna, patch antenna, monopolar patch antenna, dual-band, zeroth-order mode, TM 01 mode, omnidirectional radiation, broadside radiation.

A Triband Patch Antenna with Monopole-like and Patch-like Radiation Patterns for Multifunctional Wireless Systems

“…e comparison International Journal of Antennas and Propagation focuses on the number of antenna radiator, operation bands, size of antenna radiators in terms of their wavelengths at the lowest operating frequencies, antenna profiles in terms of wavelengths at the lowest operating frequencies, and the performance of radiation patterns. is comparison shows that just the proposed antenna, the antenna [14], and the antenna [19] employ a single one radiator to achieve the omnidirectional radiation pattern and the unidirectional radiation pattern simultaneously. However, the sizes of radiator for the two antennas [14,19] are larger than that of the proposed antenna.…”

“…is comparison shows that just the proposed antenna, the antenna [14], and the antenna [19] employ a single one radiator to achieve the omnidirectional radiation pattern and the unidirectional radiation pattern simultaneously. However, the sizes of radiator for the two antennas [14,19] are larger than that of the proposed antenna. e antenna [14] has a lower antenna profile compared with the proposed antenna, but only the proposed antenna has three operation bands.…”

“…Taking advantage of the mushroom structure, omnidirectional ZOR antennas were proposed [16,17], and a mushroom patch was inserted in a rectangular patch to generate the ZOR and TM 010 modes at the same frequency [18]. Utilizing a top-loaded small metal strip, a dual-band circular patch antenna with omnidirectional ZOR mode for the lower band and unidirectional TM 01 mode for the upper band was studied in [19].…”

“…In this paper, a compact triband square patch antenna with monopole-like and patch-like patterns is presented. Compared with the circular patch antenna [19], the proposed square patch antenna has a more compact size and better impedance matching bands to covering more communication bandwidth, so the proposed square patch antenna is more suitable to apply in multifunctional wireless systems. For the proposed square patch antenna, the method for the square radiation patch to excite monopole-like ZOR mode is introducing a rectangular metal sheet, and its performance is robust to the probe feed position.…”

Feedline Separation for Independent Control of Simultaneously Different Tx/Rx Radiation Patterns

“…The authors of [2] have investigated the use of monopole antenna for radio-frequency heating and microwave communications at 1.8, 2.4, and 2.56-GHz bands. In addition, the works presented in [3] have revealed the single circular patch antenna for Global Positioning System (GPS) application at 2.28-2.40 and 3.30-3.60 GHz. However, this kind of antenna faces the problems of lowgain radiation, low capacity and also high interference signal.…”