A high frequency ratio quadri‐band frequency independently tunable antenna with spurious‐mode suppression

Abstract

A quadri‐band frequency independently tunable patch antenna with high frequency ratio is proposed in this article. It is realized by nesting two rectangular patches and two U‐shaped patches together separated with gaps. Each patch is resonating at one band. U‐shaped patches are utilized to suppress the spurious‐mode resonances when designing antenna with high frequency ratio. Two parallel varactors are embedded on each patch to tune its resonant frequency. Measured results demonstrate the quadri‐band antenna has tunable ranges of 0.75–0.97, 1.87–2.11, 2.37–2.63, and 3.36–3.72 GHz, respectively, with a high frequency ratio of 5, low spurious‐mode resonances, comparatively high gains of 2–8 dBi and efficiencies of 30–80%.

A compact E-shaped antenna with C-shaped slots and a back-patch for multiband applications

“…In view of this, most of the multiband antennas found in the literature are developed solely to support dual-band applications [1 -12]. Although the designs in [13-25, 17, 26-29] support more than two bands, the size of the antennas are either relatively large [13][14][15][16][17][18][19][20][21][22][23] or that their geometrical structures are complicated [17,24,25,[26][27][28][29], rendering it difficult to be fabricated. Of course, the size of an antenna is wavelength or frequency dependent.…”