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A switchable dual-band dual-sense (DBDS) circularly polarized (CP) patch antenna is reported in this communication, which is implemented by dual-band phase shifter of ±90°. The proposed antenna is comprised by two annular-ring radiators, four H-shape slots, and two phase-controlled feeding networks. Four H-shape slots offer desired isolation between two paths of each feeding network, and also improve the impedance matching performance in two bands. Each dual-feed network is shared by two operating radiators, supporting simultaneous dual-band functionality. Meanwhile, the dual-band phase shifter is enabled by the folded shorted stubs that provide broadband dual-CP radiation performance. Thus, for each feeding network, −90° and 90° phase differences between two orthogonal signals can be achieved in each band, respectively, so as to meet the requirements of opposite polarizations. Two pairs of single pole single throws (SPSTs) are added in the feeding networks to acquire switchable CP characteristic, meanwhile improving the isolation between two feeding networks. As a proof-of-concept, a switchable DBDS CP antenna prototype operating at 2.45 GHz/5.8 GHz industrial scientific medical (ISM) bands is prototyped and tested with a low profile of $0.036~\lambda _{0}$. By controlling two pairs of SPSTs, the proposed patch antenna can switch from the right-handed circular polarization (RHCP)/left-handed circular polarization (LHCP) state to the LHCP/RHCP state. [ABSTRACT FROM AUTHOR]

A dual‐band dual circularly polarized (CP) patch antenna is proposed with low profile and small frequency ratio in this letter, which consists of a square patch, coupling lines, and a dual‐feed network with dispersive delay line. Noticing that this antenna is fabricated on a single‐layer substrate, thus acquiring low‐profile performance. As for the coupling scheme, the bandwidth of impedance matching is increased to achieve dual‐band radiation performance. On the premise that two orthogonal signals, which transmit in two paths of the dual‐feed network, provide equal magnitude, the circular polarization can be controlled by the corresponding phase difference. Benefited from the dispersive delay line, the requirements of quadrature phases are met to present left−/right‐handed circularly polarizations in two operating frequencies. Meanwhile, small frequency ratio can be easily achieved. To demonstrate the proposed design, the single‐layer antenna with a profile of 0.006λ0 is designed, fabricated and measured. The phase difference of two orthogonal signals is adjusted to −90° at the lower operating frequency 1.9 GHz to realize right‐handed CP characteristic, while 90° phase difference in two paths is achieved at the higher one 2.4 GHz to provide left‐handed CP characteristic. Measured results are found in reasonably a good agreement with the simulated ones. [ABSTRACT FROM AUTHOR]

A compact dual‐band circularly polarized (CP) filtering patch antenna is proposed by adopting the dispersive delay line (DDL) in this article. The in‐band and out‐of‐band phase differences of two orthogonal components are effectively controlled by the DDL to realize opposite polarization states. As perfect isolation is achieved between left‐hand circular polarization and the right‐hand one in CP antenna, by controlling the parameters of DDL, four radiation nulls are presented simultaneously, and their locations are directly determined by the phase difference, thus obtains good filtering performance with compact structure. For demonstration, dual‐band CP patch antenna is designed at 2.4 and 5.8 GHz for WLAN applications based on DDL. The simulated and measured results of fabricated prototypes show good agreement. Good out‐of‐band rejection is observed in this design, which verifies the feasibility of the proposed CP filtering strategy. [ABSTRACT FROM AUTHOR]

This paper presents a D-band (110–170 GHz) transmitter/receiver (Tx/Rx) chipset with end-fire on-chip antennas (OCAs) using 0.13-μm SiGe BiCMOS technology. The input LO signal frequency of the chipset is 31.25 GHz. A 62.5-GHz frequency doubler, a D-band 2nd-harmonic up-conversion mixer, a power amplifier (PA), and an end-fire antenna are integrated in the Tx. An end-fire antenna, a D-band low-noise amplifier (LNA), a 2nd-harmonic down-conversion mixer, and a 62.5-GHz frequency doubler are integrated in the Rx. The end-fire OCA has gain and efficiency of 4.1 dBi and 83%, respectively. Maximum measured effective isotropic radiation power (EIRP) of 9.2 dBm and conversion gain of 21 dB are achieved for the Tx and Rx, respectively. The Tx/Rx are packaged on PCBs through wire bonding and chip-to-chip wireless communication using 16QAM modulation with the data rate of 4 Gb/s is demonstrated. The DC power consumption of the whole chip is ~1150 mW, and the total chip size is 2 × 3.5 mm2. [ABSTRACT FROM AUTHOR]