This letter presents a novel broadband microstrip patch antenna with a simple geometry. Two parasitic mushroom-type arrays are incorporated along with the two radiating edges of a main radiating patch. Firstly, thanks to the mushroom-type structure, a new resonant mode, characterized as quasi-TM30 mode, is generated. Besides, the main radiating patch produces the original TM10mode. Thus, wideband performance is realized based on the two combined modes. Secondly, the current distributions on those metal patches are nearly uniform so that high gains are achieved over the entire operating bandwidth. Measured results indicate that the enhanced impedance bandwidth is from 11.9 to 18.2 GHz, which covers the whole Ku-band. Meanwhile, a nearly constant peak-radiating gain between 10 and 10.5 dBi at broadside radiation is obtained. The proposed antenna maintains the advantages of wide bandwidth, ease of fabrication, flat and high gains, and a low profile less than $\lambda_{0}/13$ thickness substrate.

In this letter, a planar frequency beam scanning antenna (FBSA) with circularly polarized (CP) radiation property is proposed. The beam scans along the narrow side and in lateral plane of the antenna. The antenna consists of two layers: eight periodic symmetrical patches are presented on the top layer as radiation elements to generate CP beam; while microstrip spoof surface plasmon polariton (SPP) transmission line is used as the feeding line, which improves the beam scanning range obviously. The antenna has been fabricated and measured to verify the theory analysis. Measured results indicate that the main beam scans from -5° to +37° in lateral plane within the operating frequency band from 12 to 16.5 GHz, of which excellent CP characteristic is also realized. The peak gain of the antenna is about 9.5dBi over the whole band.

One novel single-feed single-layer wideband circularly polarized (CP) magneto-electric dipole antenna (MEDA) with enhanced gain property is presented in this communication. By loading co-planar spiral with the radiating patch, the unidirectional radiation gain of the antenna is effectively improved while the impedance bandwidth and axial ratio (AR) bandwidth unaffected. Surface current distributions with/without the spiral are compared to reveal the antenna’s mechanism. The measurement shows that the left hand circular polarization (LHCP) antenna features impedance bandwidth from 11.4 to 18.5GHz (or 52%), an AR bandwidth from 13.2 to 18GHz (or 32%), the maximum gain of 11.1 dBic at 16.9 GHz with 3-dB gain bandwidth from 12.5 to 18.6 GHz (or 36.1%). Owning to the low profile, broadband and high gain, the proposed antenna is a capable candidate for satellite communication.

A single-layer dual-band shared-aperture antenna for vehicular communications is proposed in this paper, which adopts a coplanar millimeter-wave (mm-Wave) band antenna embedded in a microwave band antenna. In the microwave Vehicle-to-Everything (V2X) band (5.905–5.925 GHz), an annular-ring patch antenna based on the TM ₁₂ mode is designed. A pair of slots are etched out on the radiating patch to reshape the current distribution of the TM ₁₂ mode, making it more codirectionally distributed. The sidelobe level can be completely suppressed from -5.2 dB, thus achieving better broadside radiation characteristics. In the 5G mm-Wave n257 band (26.5–29.5 GHz), a substrate integrated waveguide (SIW) slotted cavity backed antenna based on TE ₄₄₀ mode is designed, which achieves high gain and low sidelobe performance. Experimental results show that the impedance bandwidth of the microwave band is 3.7% (5.74–5.96 GHz), and that of the mm-Wave band is 10.9% (26.66–29.72 GHz). The mutual performances of the two antennas are hardly affected, and the measured isolation of both ports is greater than 45 dB. The measured gain reaches 10.8 dBi and 13.7 dBi, respectively, while maintaining sidelobe levels below -14.8 dB. At the same time, the antenna profile is only 0.015 λ ₀ (λ ₀ is the wavelength in free space at low frequency). Therefore, a microwave and mm-Wave dual-band shared-aperture antenna with a compact structure and independently controllable performance is realized, which provides a promising candidate for different vehicular communication application scenarios.

A novel probe‐feed single‐layer circular patch antenna with dual‐band dual‐mode dual polarisation is proposed in this study. By using modified mushroom structure, dual‐band dual‐mode characteristic is realised as former designs. Due to the loading structure including four curved patches added around the circular radiating patch, bandwidth is broadened for the patch mode ( n = 1 mode) with unidirectional linearly polarised characteristics at the upper frequency band. By loading with four curved branches in the ground plane, circularly polarised property for the dipole mode ( n = 0 mode) with omnidirectional radiation patterns is achieved at the lower frequency band. Parameter analysis is made to study this antenna and one prototype is fabricated to confirm the property. Moreover, the measured results are obtained with −10 dB impedance bandwidths of 227.5 MHz (5.1% at the centre frequency of 4.42 GHz) and 857.5 MHz (14.9% at the centre frequency of 5.74 GHz), and maximum gain of 1.1 and 7.1 dB for the dipole mode and patch mode, respectively. With the advantages of simple structure, wide bandwidth, radiation pattern selectivity and polarisation diversity, this antenna concept is valuable in wireless communications.

In this communication, a novel wideband fixed-beam leaky-wave antenna (LWA) is proposed. The antenna is designed based on air-filled substrate integrated waveguide (SIW), which is composed of one layer of printed circuit board (PCB) in the middle and two layers of thin copper plates on the top and bottom. The different layers are aligned and fixed by screws. A long slot is etched on the top surface of air-filled SIW as a radiator. Due to the dispersive characteristic of the air-filled SIW, the antenna can radiate at a fixed direction over a wideband. To the best of our knowledge, this is the first time that the air-filled SIW is adopted for LWA design. The proposed antenna is designed, fabricated, and tested. The measured results show that its wide operating bandwidth reaches up to 37.0%, ranging from 11 to 16 GHz. The excellent fixed-beam radiation performance is obtained over the operating bandwidth. The radiation direction is fixed at 59° with only ±3° variation, and the peak gain is within 14.0-15.3 dBi. Although the beam angle can only be fixed nearly the endfire, this method offers a simple way to realize wideband fixed-beam feature.