KENSINGTON -- AT&T is facing another delay in its efforts to get a sixth cell phone antenna approved here after Contra Costa supervisors on July 8 asked the company to pay to investigate a so-called "coverage gap" around two proposed antenna locations.

The independent peer review for an antenna proposed at 110 Ardmore Road or 801 Coventry Road would determine whether the installation is necessary to improve cell phone reception and handle what the company characterizes as the exploding demand for wireless capacity and data downloads that could at some point swamp the existing system.

Opponents of placing the antenna at the top of utility poles at either of the two sites deny that a coverage gap exists and contend that the antenna can just as easily be installed on a pole in the commercial area along Arlington Boulevard or dispensed with entirely.

The board's action, principally at the urging of Supervisor John Gioia, who represents Kensington, is the latest in a series of hearings, appeals, moves and counter moves since AT&T filed the antenna applications in January of last year.

Residents have complained about potential health issues related to microwave radiation released from the antennas, as well as blocked views, negative consequences on real estate values, potential for noise and other issues they say are posed by locating the antennas in their neighborhoods.

Supervisors on Dec. 17 turned back an appeal of a county Planning Commission decision approving plans to mount antennas on PG&E poles at five other Kensington locations: 121 Windsor Ave., 8 Sunset Drive, 18 Highgate Road, 4 Stratford Road and 248 Grizzly Peak Blvd.

AT&T agreed in April to pursue an alternative site in the face of neighborhood opposition to an antenna at 110 Ardmore Road. The company later received Planning Commission approval to place the disputed antenna at 801 Coventry Road, a couple of blocks from 110 Ardmore.

Residents then appealed the decision on 801 Coventry to the supervisors.

The four other board members joined Gioia in voting to require the peer review, but supervisors Candace Andersen and Mary Piepho expressed concerns about the additional delay, saying that all communities have the responsibility to allow adequate cell phone coverage for emergency response and for residents of other communities who may be passing through.

AT&T agreed to extend a so-called "shot clock," an 18-month Federal Communications Commission limit on consideration of cell phone antenna applications, on both locations.

Supervisors plan to take up the matter again at their Aug. 12 meeting, the deadline for the peer review to be completed.

"At some point we need to make a decision," Piepho said.