Browse Prior Art Database

Wideband Helical Antenna

IP.com Disclosure Number: IPCOM000204631D
Original Publication Date: 2011-Mar-07
Included in the Prior Art Database: 2011-Mar-07
Document File: 3 page(s) / 561K

Publishing Venue

Motorola

Related People

Faraone, Antonio: INVENTOR

Abstract

The structure comprises various helical sections which are suitably interconnected and/or grounded in order to realize an antenna presenting two resonant modes at near frequencies, thus synthesizing a continuous wideband response. Specifics of the antenna construction are provided in the disclosure details.

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Wideband Helical Antenna

By Antonio Faraone

Motorola Solutions

 

ABSTRACT

Achieving wideband frequency performance in two-way radios is difficult if the total radio size [chassis plus antenna] is size limited. Therefore, a new antenna designed featuring broader band compared with traditional ones, for the same antenna length, can provide product differentiation. An antenna structure featuring the desired wideband behavior thanks to the synthesis of adjacent resonant modes in a compact size is presented, with measured data showing that the whole UHF band (380-520 MHz) may be covered in an antenna embodiment shorter than 11 cm. 

PROBLEM

The frequency range of the UHF band used for the public safety radio communications spans 380 MHz – 520 MHz. Due to its wide fractional bandwidth and the fundamental gain-bandwidth limitation of limited size antennas, typical helical antennas used for the portable radios often do not provide good VSWR for the entire UHF band. In order to overcome these issues, a wideband UHF antenna solution with a simple and low profile structure for potable radios is presented.

The proposed wideband helical antenna (WHA) is a low-Q antenna system with wide band frequency response and compact size with good radiation performance.

SOLUTION

The antenna structure illustrated in [1] is modified by routing the antenna conductors (strips or wires) along an helical path so as to effectively reduce the antenna height without altering the required inter-element couplings that produce the desired wideband response (Fig. 1).

Fig. 1 – WHA geometry.

OPERATION IN THE UHF BAND

The WHA features two coupled elongated conductors. A shorter one which is fed with RF power and a longer one which is grounded near the RF feed and runs parallel to the shorter one, then is folded at the top and runs back downwards parallel to the shorter conductor but on the...