in some mobile systems, intelligent antennas are used to increase efficiency in a wide frequency band and different environmental and electromagnetic conditions. environmental factors, such as position of nearby objects, antenna mobility and even user type, can vary the antenna input impedance appreciably. therefore, it is necessary to incorporate an adaptive impedance matching circuit between ...

In this paper a design of triple band one turn helical antenna without ground plain for center frequency of 2.4 GHz, 3.6 GHz, and 5.4 GHz is discuss. These frequencies are selected such that the antenna radiate for continuous band of 2 GHz to 6.8 GHz frequency with variable gain. The purpose of this novel design is to enhance the gain as well as bandwidth. The triple band is achieved by three c...

This paper presents an element of a 2×2-element array antenna for Inmarsat BGAN/GPS applications. The element is an axial mode printed quadrifilar helical antenna that has been integrated with a compact feed network to provide sequential phase rotation for circular polarization (CP) radiation. The novel integrated lumped-element feed network is designed to provide a balanced RF power to the fou...

We are presenting by this paper on helical antennas which find important applications in communication systems, primarily because of their circular polarization and wide bandwidth. The helical antenna, first introduced by Kraus in 1946, The geometry of larger helical shape type antenna, which is a doubly helical structure, is fully described by five independent parameters, with the including tw...

A stacked rectangular microstrip antenna with a shorting plate and a helical pin is proposed as a car antenna for triple band operation in ITS. The proposed antenna operates as a conventional stacked microstrip antenna at the highest frequency band. At the middle and the lowest frequency bands, the antenna radiates at low elevation angles from the helical pin and the shorting plate. In this pap...

In 1946, John D. Kraus invented the helical-beam antenna (or axialmode helix).1 Commencing with Kraus’s correct hypothesis that travelling-wave structures then used in electromagnetic devices would make efficient antennas, the helix antenna has proven to be the radiator of choice for many radio astronomy and spacescience applications. The helical antenna has been carried to the Moon and Mars, a...

A practical normal-mode helical antenna array together with a new method for the compensation of mutual coupling effect is proposed for the efficient adaptive nulling of interferences in a mobile communication environment. The helical antenna array is shown to be able to generate deeper nulls than an equivalent monopole antenna array in the presence of mutual coupling effect. The helical antenn...

Octafilar helical antenna (OFHA) is proposed for handheld ultra‐high‐frequency (UHF) radio frequency identification (RFID) reader. The investigated antenna configuration consists of OFHA placed on reader device in the presence of human hand model. The antenna is designed at UHF band centered at 915 MHz. The antenna return loss, axial ratio, gain, co‐polarized and cross...