A Wideband, Low-Profile Log-Periodic Monopole Array With End-Fire Scanning Beams

Novel low profile ultra‐wideband capacitance loaded log‐periodic monopole array with reduced transverse dimension

“…The proposed antenna slightly modified the one presented in [20]. As compared with the works in [18,19] and [20], this proposed antenna possesses a much wider impedance bandwidth with nearly the same profile height. Moreover, higher radiation efficiency is greatly improved as compared with the design in [18,19], and much compact transverse size is achieved as compared with the design in [20].…”

“…However, the radiation efficiency is relatively low, due to the lumped resistors at the end of the strip lines for residual power absorption. The same disadvantage is also introduced in the design reported in [19]. Another conformal log-periodic array, with top-hat loaded monopoles, covering an ultra-wide band of 2-18 GHz was proposed in [20].…”

“…2, three types of monopoles are introduced in the proposed array. The monopoles operating at the higher frequency band (4.69-10.7 GHz) are designed following the procedure for conventional log-periodic monopole array [19], Seven monopoles with different heights h i (i = 1, 2, 3, …, 7) but same diameter d m are introduced for this band. The heights of metallic vertical posts approximately equal to λ/4 corresponding to each resonant frequency as shown in Fig.…”

“…Therefore, the main difficulty in the design of logperiodic monopole antenna is to reduce the profile height as well as to minimise the transverse size for further antenna array development. Possible approaches to reduce profile height including top-hat loading [18][19][20][21][22], meandering the arms of monopoles [23,24], and introducing fractal sections in monopoles [25,26].…”

Compact broadband printed quasi‐Yagi antenna with series‐fed double monopole

“…With the fast development of wireless communication systems, such as 2G, 3G, LTE, Wi-Fi, WiMAX, and ZigBee, it is desirable to have following antenna features: unidirectional radiation pattern, wide bandwidth (BW), stable gain, stable radiation pattern, easy integration, low profile, and so on. 1,2 The printed quasi-Yagi antenna (PQYA) with dipole elements, which was first proposed by Qian et al, 3 has been extensively studied to achieve aforementioned properties either by modifying feeding structures or by modifying the shape of the driven elements. [4][5][6][7][8][9] Various reported designs of PQYA consist of a dipole as driven and director elements with truncated ground behind the driven element as a reflector.…”