Study on Horizontally Polarized Omnidirectional Microstrip Antenna

A number of studies on the characteristics of cylindrical rectangular and circular microstrip antennas have been available in the open literature. The investigations of cylindrical triangular microstrip antennas, however, are relatively scant. Since the triangular patch can be a good substitute for the rectangular patch in microstrip antenna and array designs, due to its physically smaller patch size than the rectangular and circular ones, the related studies become interesting and important. This motivates the present study. In this article, both the cavity-model and full-wave analyses of cylindrical triangular microstrip antennas are described. Curvature effects on the input impedance and radiation characteristics for the antenna with various cylinder radii at its fundamental TM/sub 10/ mode are analyzed. Measured input impedances and radiation patterns are also presented for comparison. In addition, curvature effects on the cross-polarization characteristics of a triangular microstrip antenna at the TM/sub 10/ mode are also analyzed.

A new configuration for a circularly polarised microstrip antenna with an omnidirectional pattern is proposed. This antenna consists of two rectangular patches with perturbation segments, which are arranged back-to-back relative to a coplanar waveguide (CPW) on a ground plane. The characteristics of the proposed antenna were clarified by experiments, and the mechanism to produce the circular polarisation was proved by using an electromagnetic simulator. The radiation patterns and input impedances were measured as a parameter of the width of the perturbation segment. Good circularly polarised radiation patterns with an omnidirectional pattern and input impedance characteristics were obtained.

The ground-based augmentation system (GBAS) is a system for receiving supplementary information directly from a ground-based transmitter using the global navigation satellite system (GNSS). The GBAS is also used for precise approach and landing of aircraft. The antenna used for transmission and reception exhibits the quadrangular array structure of a dipole antenna having linear polarization with VHF data broadcast (VDB). However, in the case of a VDB antenna, signal cancellation and interference among individual elements may occur.In this paper, we describe an omni-directional microstrip antenna that can replace the VDB antenna used in GBAS. The proposed design reduces the ground plane in a λ/4 folded microstrip antenna in order to have omni-directional characteristics and to radiate without affecting the ground plane itself. To miniaturize the physical size of the antenna, a metal plate is added between the openings using a perturbing effect.The designed antenna is verified through simulation. The size of the radiating element is 318 mm (0.12λ) × 100 mm (0.038λ) × 221 mm (0.083λ), whereas the size of the radiating element of a λ/4 folded microstrip antenna is 568 mm (0.214λ) × 100 mm (0.038λ) × 608 mm (0.23λ). Thus, the size of the radiating element is reduced by 79.7%. As a result of the electrical characteristics of the designed antenna, S 11 is −37.1 dB, the −10-dB bandwidth is 0.56 MHz, and its gain is 1.09 dBi at a center frequency of 113 MHz. The radiation pattern shows the desired omni-directional characteristic. It is thus confirmed that the proposed antenna can replace the existing VDB antenna used in GBAS.

LoRa has become one of the most efficient solutions in implementing the Internet of Things (IoT) due to its essential features, such as cost-effectiveness and low-power wireless platform. The microstrip antenna is a unique type of antenna known for its lightweight, small size, ease of fabrication, and the ability to conform to various surfaces. Compared to other types of antennas, it has a smaller physical footprint. In terms of radiation pattern measurement, the microstrip antenna exhibits bidirectional characteristics, meaning it focuses the signal radiation in two specific directions. The objective of this research is to examine and evaluate how the communication quality between LoRa modules is affected by using a bidirectional microstrip antenna. This is compared to the built-in LoRa antenna, which has an omnidirectional radiation pattern, distributing signals evenly in all directions. The study aims to analyze the impact of the bidirectional microstrip antenna on the performance and communication range within the LoRa network. Based on the performance comparison graph of Received Signal Strength Indicator (RSSI) for each antenna – the built-in antenna, the microstrip antenna, and the microstrip antenna at a 90° tilt – it is evident that the microstrip antenna at a 90° tilt exhibits the highest RSSI value, while the built-in antenna shows the lowest RSSI value.

Colinear array antennas constructed from coaxial elements such as sleeve dipoles or patch antennas using parasitic cylinders are employed as omnidirectional antennas in mobile communication. In microcellular and wireless LAN systems, simple, small-size, and low-cost antennas for base stations are desired. The paper proposes a base station antenna that satisfies these requirements. The proposed antenna configuration is a back-to-back narrow-width rectangular patch fed by a CPW. The experimental results for an element antenna and an array antenna are described. Good omnidirectional radiation pattern characteristics have been obtained.

A compact horizontally polarized (HP) omnidirectional antenna with broadband characteristic is presented. The antenna is composed of four planar folded dipole antennas (PFDAs) as radiation elements of a square array and a broadband microstrip feeding structure composed of baluns and matching networks. The folded dipole antennas are chosen in order to achieve wide bandwidth operation within a compact size. The folded dipole elements are modified to compensate for the mutual coupling effects and also to improve the bandwidth and radiation performance of the antenna. The antenna is fabricated and its input impedance and radiation pattern are measured. The measured 10 dB return loss bandwidth is about 53.2% (1.19-2 GHz) and the gain variation in all directions of azimuth plane is less than 2 dB over the frequency band 1.2-1.9 GHz, and is increased to 2.8 dB at 2 GHz. The gain is almost constant over the entire band with a peak gain about 1.2 dB. The co-pol and cross-pol isolation is more than 20 dB for all azimuth directions and frequencies over the entire band.

A design of a wideband small spiral antenna for SAR is proposed. First, to miniaturize the spiral size, characteristics of input impedance and axial ratio for equiangular and Archimedean spiral antennas are analyzed regarding the effects of substrate and spiral turn. It is found that the miniaturized 6-turn Archimedean spiral antenna on a FR-4 substrate which is 4.4 cm in diameter has the good characteristics over a frequency range of 3 GHz to 20 GHz. Second, by experimentally observing time domain radar characteristics, it is confirmed that a cavity 6.1 cm deep sufficiently filled with an EM absorber is effective to obtain clear radar signals. It is also found that leaving a space between Tx and Rx antennas is important to improve the power ratio of a reflected wave to a direct wave.

The increasing use of UAVs (Unmanned Aerial Vehicles) for mapping, surveillance, environmental monitoring, and logistics has heightened the demand for reliable telemetry links between the aircraft and the Ground Control Station (GCS). Telemetry systems require antennas that are compact, low-cost, and capable of dual-band operation at 2.4 GHz and 5.8 GHz, which are widely used for control and data transmission. Microstrip antennas are suitable because of their light weight, compact size, and ease of integration, but their narrow bandwidth and limited gain reduce effectiveness in long-range UAV missions. This study presents a planar omnidirectional microstrip antenna designed for UAV GCS applications. The design adopts a coaxial collinear configuration with a 180° offset and integrates forked-open-ended stubs, U-slots, and Y-slots to enhance dual bandwidth and improve impedance matching. Fabricated on a low-cost FR- 4 substrate, the antenna was optimized through simulations and verified experimentally. The results show operating ranges of 2.258–2.571 GHz and 3.978–5.887 GHz, with bandwidths of 313 MHz and 1.909 MHz, return losses of 20.08 dB and 14.48 dB, and peak gains of 3.24 dBi and 7.09 dBi, respectively. Compared to typical dual-band microstrip antennas that often suffer from narrow bandwidth, moderate gain, or dependence on costly substrates, the proposed design achieves wider bandwidth and higher gain using simple slot modifications on low-cost FR-4. This balance of high performance and affordability highlights the novelty of the work, offering a practical and manufacturable solution for UAV telemetry applications.

This paper presented one novel microstrip antenna with triple-band triple-mode and triple-polarization (TBTMTP) characteristics. In the lower frequency band, the antenna operates in the linearly polarized (LP) dipole mode with omnidirectional radiation pattern along the YOZ plane which is like one horizontally located dipole antenna. In the middle frequency band, the antenna operates in the LP dipole mode with omnidirectional radiation pattern along the XOY plane which is like one vertically located dipole antenna. While in the upper frequency band, the antenna works in the circularly polarized (CP) patch mode with directional radiation patterns along the Z-axis direction. Three modes with different patterns were excited in three different bands because of the mutual-coupling periodical circular patches and inductance metal pins. By etching inverted L shaped slot in the down circular mental patch, CP is realized for the patch mode without affecting the other two modes. The surface current distribution is introduced to analyze the antenna working principle. Due to the compact structure, easy fabrication, radiation pattern selectivity and polarized diversity, this antenna has potential application value in wireless communications in future.

This paper presents s new circularly polarized (CP) omnidirectional microstrip antenna array. The designed antenna array has back-to-back structure, four series-fed patch antenna elements on each side. The resonant bandwidth of this array is about 7.4% with center frequency 17.5 GHz. The antenna array has CP gain variation in the main lobe plane is around ±2.5 dBic, axial ratio (AR) in the main lobe plane is less than 3 dB, peak CP gain is 9.36 dBic and half-power beam-width is only 15 deg.

The input impedance, resonant frequency, and radiation characteristics of the annular ring patch microstrip antennas shorted at the outer periphery are studied. Analytic results for the dominant and higher-order modes are compared with experimental data and previous results. The radiation conductance, the fringing field, and the effect of feed position, i.e., a coaxial probe, are included in the analysis. Two antennas, A and B, were fabricated and tested. Their calculated resonant frequencies for the TM/sub 11/ mode are 2.174642 GHz and 3.143697 GHz for model A and model B, respectively, which agree well with the measured ones, 2.19913 GHz and 3.15452 GHz, respectively. >

The approach in this book is historical and practical. It covers basic designs in more detail than other microstrip antenna books that tend to skip important electrical properties and implementation aspects of these types of antennas. Examples include: quarter-wave patch, quarter by quarter patch, detailed design method for rectangular circularly polarized patch, the use of the TM11 (linear and broadside CP), TM21 (monopole CP pattern) and TM02 (monopole linear) circular patch modes in designs, dual-band antenna designs which allow for independent dual-band frequencies. Limits on broadband matching are discussed. The appendix contains useful simple matching approaches, design details (gain, matching, sidelobes) of the little-studied omnidirectional microstrip antenna (OMA), limits and properties of common single and dual band Planar Inverted F Antenna (PIFA) antenna designs. The second edition has numerous additions to the earlier text which will make the concepts presented clearer. New cavity model analysis equations of circular polarization bandwidth, axial ratio bandwidth and power fraction bandwidth have been included. The section on omnidirectional microstrip antennas is expanded with further design options and analysis. This is also true of the section on Planar Inverted F (PIFA) antennas. The discovery and description of the fictious resonance mode of a microstrip slot antenna has been added to that section. Appendix A, on microstrip antenna substrates has been expanded to provide more detail on the types of substrate and their composition. This is often neglected in other texts. An appendix on elementary impedance matching techniques has been added as these methods have proven useful in my industrial work.

This letter describes a broadband planar antenna embedded in LTE700/GSM handheld terminals. The antenna consists of a T-shaped strip fed by a 50-Ω coaxial cable and a shorted strip excited by capacitive coupling. The capacitively coupled shorted strip shows the resonance at the lower frequency band, and the T-shaped strip presents good matching at the higher frequency band, because the characteristics of input impedance are affected by the capacitive coupling. The proposed antenna was simulated and fabricated. The measured bandwidth based on 3:1 VSWR was 0.62–1.53 GHz, which covers the frequencies used for LTE700, GSM800/850/900 mobile communications as well as the military applications. This antenna would be also useful for broadband wireless communications using the technique such as software-defined radio or cognitive radio. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26211

This communication presents a compact cavity antenna with horizontally polarized omnidirectional radiation pattern. The dimension miniaturization of an omnidirectional resonant cavity is achieved by loading the capacitive substrate-integrated impedance surface (SIIS). Specifically, the SIIS is composed of a row of blind vias that are periodically arranged near the antenna's radiating aperture, effectively providing a shunt capacitance that can be controlled by the insertion depth, period, and diameter of blind vias. The dispersion of the omnidirectional cavity antenna is theoretically studied and the explicit design formula is derived. Our results report that loading the capacitive SIIS can significantly reduce the size of an omnidirectional cavity antenna (52.4%). As a proof of concept, a prototype was fabricated and characterized, with a good agreement between the measurement and simulation results. The results also show that omnidirectional radiation patterns can be maintained well when the operating frequency is tuned, with the realized gain slightly fluctuated between 2.7 and 3.2 dBi. The proposed antenna exhibits potentials in volume-limited omnidirectional wireless communication systems.

An omnidirectional antenna with a compact size is presented. The diameter of the proposed antenna is 100 mm and the height is ∼0.1λ L (12 mm). It consists of two dipoles and four shorting pins. With this configuration, the impedance bandwidth of the proposed antenna covers 2.4–2.6 GHz. Within the bandwidth, the proposed antenna has a stable bidirectional radiation pattern in the E‐plane and the omnidirectional radiation pattern in the H‐plane. The geometry of the antenna is investigated and optimised by the ANSYS high‐frequency structure simulator. The fabricated antenna is compact enough to be integrated into a communication system. Measured and simulated results are also obtained and compared at the end of this work.