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This communication presents a novel compact planar monopole antenna configuration: the spirograph planar monopole antenna (SPMA) covering C-/X-Band (4–12 GHz). The antenna has an invariant omnidirectional radiation pattern across the frequency band with no multi-lobe effect and low cross-polarization. The SPMA radiating element size is less than \lambda /2 at the highest frequency of operation such that it can be used as a beam scanning array element. For the SPMA, it was found that increasing the number of points in the antenna shape miniaturizes the radiating element and increases the impedance bandwidth. A prototype SPMA was fabricated and measured for impedance and radiation performance. [ABSTRACT FROM PUBLISHER]

Microstrip patch antenna with multi-frequency and dual-mode is presented in this communication. The introduction of metamaterial substrate made of modified mushroom-type electromagnetic band-gap (EBG) structure enables the multi- functions. The composite right/left-handed transmission line (CRLH TL) theory and multi-conductor transmission line (MTL) theory are introduced to analyze and design this kind of antenna. Three modes including one monopolar radiation pattern in the n=0 mode and two patch-like radiation patterns in the n=-1, 1 modes respectively are analyzed and can be tuned by the parameters of the EBG structure. Since geometry of the radiating patch does not affect the infinite wavelength mode, circular polarization (CP) is obtained for the n=+1 mode by truncating the square radiating patch with linear polarization (LP) for the n=0 mode staying unchanged. Thus dual polarized antenna is obtained. Two prototypes of probe-fed patch antennas are fabricated to verify the theory analysis. [ABSTRACT FROM PUBLISHER]

A novel broadband high gain periodic endfire antenna is presented. Broad bandwidth is realized by using a parallel strip line (PSL) feed and bowtie dipole elements while gain enhancement is achieved by loading split-ring resonator (SRR) structure in the endfire direction. The measurements show that SRR-loaded antenna presents gain of about 6.2~9.9 dB in the whole working band (5.1~8.2 GHz), which is about 1.3~4.2 dB more than the unloaded one. This antenna can be used in wireless communication systems for its advantages of broad bandwidth and high gain. [ABSTRACT FROM PUBLISHER]