A dual-fed, delf-diplexing planer inverted F antenna and an associated RF front-end are described. It is shown that co-desin of the antenna and front-end can be used to double the operational band width, without significant size of performance penalties. Indeed, the use of two feeds allows the antenna to be self-diplexingm which results in improved overall efficiency.@en

The impedenace change that occurs when the user holds a mobile phone antenna is a well-known problem. This paper analyses the contributions to this change for a dual-band PIFA. In particular, the contribution of the slot is shown and a method of reducing it is proposed and analyzed.@en

This paper presents a radiating and balanced mode anallysis of plannar inverted F antennas (PIFAs) mounted on wave-length-scale printed circuit boards (PCBs). The radiating mode shows, in a direct way, the extent to which the PCB influences both radiation and bandwidth. The balanced mode shows that the shorting pin acts as an impedance transformer in combination with a parallel reactance. Importantly, it can also be used to show that slots in the PIFA top plate nominally provide series reactance when the slot opening is close to feed Understanding of this behavior allows bandwidth improvements to be realized. It also allows dual-band antennas to be designed in a straightforward manner.@en

A slotted PILA, often referred to as a "C-patch" is shown. No rigorous analysis of the optimum slot position of this type of antenna is known. It is proposed that the optimum slot position can be determined by modeling the antenna as the addition of radiating and balanced mode impedances based on Boyle (2005). Such an analysis can be extended to PIFA where the feed and shorting pins are on the same side of the slot.@en

User interaction causes a change in the antenna driving point impedance that leads to aloss of performance and perhaps most noticeably to the user, a degradationin baterry life. It has previously been shown [1] that the slot of a daul-band PIFA, with an opening adjacent to the feed and shorting pin, acts as a reactive circuit. Indeed, the slot could simply be replaced with discrete components: there is a strong motivation to do this when user interaction is considered. The slot acts as a transmission line and is susceptible to user interaction, since it is probable that part of the user's hand will cross the slot. The interaction mechanism does not exist with discrete components. In the sections that floow, the effect of user interactionon the fundamental performance of the antenna and slot is analyzed at both GSM and DCS. Conventional antennas ( with a slot) and those tuned using discrete components are considered.@en

In Boyle (2002), a radiating and balanced mode analysis illustrated the effect of a planar inverted F antenna (PIFA) shorting pin. Here an extended analysis is based on the general condition that the PIFA shorting pin does not connect to ground but, rather, to an arbitrary load. The special case of an open-circuit load impedance is then used to analyze the effect of a slot in the planar section of the antenna.@en