Kevin R. Boyle

Radiating and balanced mode analysis of PIFA antennas

This paper presents a radiating and balanced mode analysis of planar inverted F antennas (PIFAs) mounted on wavelength-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 the feed. Understanding of this behavior allows bandwidth improvements to be realized. It also allows dual-band antennas to be designed in a straightforward manner.

Radiation patterns and correlation of closely spaced linear antennas

A simple point source analysis is used to prove that, in theory, completely decorrelated reception can be achieved from two linear antennas with an arbitrarily small spacing. The conditions necessary to achieve this are consistent with two high gain (superdirective) beams in opposite directions. It is shown that the horizontal radiation patterns and correlation coefficient of arrays of vertically orientated linear antennas can be found via an exact relation to simple, point-source theory that includes the effects of mutual coupling. This theory leads to practically achievable optimum diversity designs at closer spacings than previously thought possible. The theory is illustrated for a dual antenna configuration and can be extended to multiple antennas.

A novel dual-fed, self-diplexing PIFA and RF front-end (PIN-DF/sup 2/-PIFA)

The concept of using a dual-fed, self-diplexing PIFA with a highly optimized RF front-end has been analyzed. The feed structure is arranged to provide both diplexing action and impedance broadbanding in the best technology available in a mobile phone - the technology currently used to fabricate the antenna. The measured average total efficiency (including the effects of mismatch) of the design presented, including the antenna, diplexing and transmit/receive switching, is 81% at the GSM band and 72% at the DCS band. The return loss is particularly good in the transmit bands at less than -16 dB in the GSM band and -11 dB in the DCS band. This is expected to yield further efficiency improvements in the subsequent RF circuitry of a phone. Improved performance can be traded for either bandwidth or antenna size. The bandwidth can be approximately doubled using this technique (for a return loss of -6 dB) with a small loss of average efficiency. This loss of efficiency is more than recovered by the highly efficient diplexing action of the antenna in combination with the out-of-band impedance presented by SAW filters. Alternatively, the antenna may be reduced in size by a factor of approximately two.

Radiating and balanced mode analysis of user interaction with PIFAs

The effect of user interaction on the fundamental performance of planar inverted-F antenna (PIFA) and slot is analyzed at both GSM and DCS. Conventional antennas (with a slot) and those tuned using discrete components are considered.

Radiating and balanced mode analysis of PIFA slots

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.

Analysis of Cellular Antennas for Hearing-Aid Compatible Mobile Phones

The Federal Communications Commission ensures that a certain portion of mobile phones sold in the United States are hearing-aid compatible. When the phone is tested for compatibility, the spatial near-field distribution generated by the phone in the vicinity of its acoustic output is used as the assessment criteria. Certain types of cellular antennas are known partial solutions for the radio-frequency related challenges of hearing-aid compatibility. We briefly summarize the characteristics of these antennas, introducing a new figure-of-merit based on a radiating and balanced mode analysis. We then introduce a class of dual-feed, dual-radiator cellular antennas as promising new candidates for enabling hearing-aid compatibility. It is shown that the proposed antennas, utilized with proper matching circuits, have inherent characteristics that make them attractive solutions for hearing-aid compatible mobile phones.

On the optimum dimensions of slotted PILAs/PIFAs

A slotted PILA, often referred to as a C-patch is presented. 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 antennas as the addition of radiation and balanced mode impedances. Such an analysis can be extended to PIFA where the feed and shorting pins are on the same side of the slot