This paper presents a new wideband and circularly polarised (CP) slot antenna realised by using an L-shaped feed underneath the cross-slot antenna, and tapered to the conventional microstrip feed-line. The proposed antenna is fabricated with an area of 75 × 80 mm 2 . The simulated results showed that the antenna had an impedance matching bandwidth of 34% from 1.3 to 1.83 GHz, and an axial ratio (AR) bandwidth of 20% from 1.36 to 1.66 GHz. A maximum gain value of 3.4 -3.8 dBi has been achieved within the operating band. The proposed antenna is of a simple and single-substrate structure, suitable for the Global Navigation Satellite Systems (GNSS) application. The impedance bandwidth and radiation patterns have been confirmed by measurement.

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This paper proposes the integration of a dual‐band bandpass filter and antenna using a filter synthesis method. A dual‐mode perturbed patch resonator and a dual‐mode patch antenna are used in the implementation. The two patches are placed back‐to‐back to share a common ground. To increase the degree of freedom in controlling the channel bandwidths and to avoid radiation interference, a slot coupling technique is used to couple both patches. The patch resonator performs the signal splitting and combining function while the patch antenna contributes to the filtering poles and performs the radiating function. Good agreements have been achieved between the measurements of the prototype device and the simulations.

In this paper, a dual-polarisation shared-aperture duplex antenna is presented for satellite communications at the standard microwave Ku-band, based on the integrated filtering-antenna concept and co-design approach. The design relies on the use of resonators coupled to the radiating dual-band dual-polarisation antenna. The resonant patch antenna forms one pole of each channel filter, resulting in a third-order filter in the Rx channel and a second-order filter in the Tx channel. The Rx and Tx ports of the antenna take in horizontal and vertical linear polarisations, respectively. The integrated duplexer helps to increase the isolation between the ports and the selectivity of each channel. The integration between the filter and the antenna is achieved by electromagnetic coupling, without the need of external matching circuits. Thus it attains a compact footprint. The operation frequencies of the demonstrated duplex antenna are from 11 to 12.5 GHz (12.8%) for the downlink to the Rx port, and from 13 to 14.4 GHz (10.2%) for the uplink at the Tx port. High port-to-port isolation of over 40 dB is realized to reduce channel interference. Flat in-band average gains are achieved to be 7.8 and 8.3 dBi, for the low-and high-bands, respectively.

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