City dwellers with their large choice of FM radio stations have long been the envy of rural residents who have had to mount huge antennas on their roofs to receive much of anything on FM.

But today, with a multitude of stations and a landscape filled with steel and granite towers that bounce their beams around, city-dwellers also need antennas. And if the Federal Communications Commission is successful in its effort to narrow the bandwidths and cram more stations on the FM dial, an antenna will be even more necessary for clear reception.

But for those of us who live in apartments, co-ops and condos and can't put up an outdoor antenna, dipoles -- those T-shaped, copper wire-lined strips of clear flat plastic -- were about all that was available. Affixed to the wall behind the stereo rig, they helped some; but their direction couldn't be changed.

Rabbit ears could help but, since FM beams are horizontally polarized, they had to be opened straight out horizontally and turned for the best reception.

Rabbit ears work best if they're placed on their sides, on a wall or the cabinet containing your stereo rig, so that the two poles can be extended and turned. Ideally, however, the poles should be parallel, which isn't always possible.

Dennesen Electrostatic Inc. (Box 51, Beverly, Massachusetts 01915) has developed an FM antenna that makes ideal use of rabbit ears. Owner Frank Dennesen says it increases gain 8.5 dB over a dipole.

Shown for the first time in a prototype model at the Consumer Electronics Show in Chicago this summer, the Dennesen Polaris Indoor FM Antenna consists of two extendable poles attached to a rectangular block ready for wall-mounting. The poles are swung horizontally by hand until reception is maximized. The cable from the antenna outlet on the tuner or receiver can be switched between two sockets on either end of the block, increasing directionality.

This model, which should be available by September, will list at $39. A version with a tuning system and longer poles will list for $79. A stand will be available for either unit, allowing the antenna to be placed at ceiling height and rotated 360 degrees.

In a test, the unit proved capable of dealing with weak reception and multi-path distortion. Stereo stations that could only be received in mono with a dipole could be heard clearly in stereo.

The other four indoor FM antennas, made by Winegard, Sony and Technics, all consist of a bar about 18 inches long that pivots on a small base for directional response and elimination of multi-path distortion. In the Sony and Technics models, the base has a tuning control that can be turned to the frequency of the station. The antenna can be placed on top of a receiver or tuner.

Winegard Company (3000 Kirkwood St., Burlington, Iowa 52601), which manufactures a variety of television and home and auto radio antennas and signal-boosters, has two FM Models. The stripped-down FM- 2400 Stereo-Ceptor, which lists for $42.75, consists of a 19-inch bar that rotates and is not recommended for long-distance reception. The FM-4400 Stereotron, which lists for $74.95, has the bar plus a solid-state circuit that amplifies FM signals an average of 5.6 times while providing proper phasing of signals and optimum signal-to-noise ratio. Stations that were barely audible with a dipole because of either weak signals or multi-path distortion could be tuned in loud and clear with the use of the amplifier and the bar on the Stereotron in a test. The Stereo-Ceptor handled these problems, especially the problem of gain, less well but still adequately eliminated distortion.

Neither the Sony nor the Technics antenna employs signal amplifiers to boost reception. They're passive units designed to deal with the fuzzy sound, drifting signals and poor stereo separation caused by distortion.

The Sony Helical FM Antenna Antenna AN-300 (Sony Consumer Products Co., 9 West 57th Street, New York City 10019), which lists at $80, has a 20-inch tube, longer than any of the other three similar models, that can be rotated by hand. A frequency control on the base tunes for optimum reception. This can be done either manually or automatically when used with most Sony frequency-synthesis tuners and receivers. The antenna performed well, eliminating reflected signals and receiving more direct signals, especially at the lower end of the FM dial -- traditional home of religious, college and other educational stations, including many National Public Radio outlets.

It was at this end that the $90 Technics FM Wing Antenna, SH-F101, (Technics, 1 Panasonic Way, Secaucus, New Jersey 07094), did less well, perhaps because its antenna is less than 17 inches wide, shorter than the Winegard and Sony. The antenna can be tilted as well as rotated. Like the Sony AN-300, it can be internally tuned for specific broadcast frequencies, either manually or, with most Technics quartz synthesizer tuners and receivers, automatically.

The trend toward specially designed indoor FM antennas began in 1977 when BIC introduced its first Beam Box, the $90 FM- 10, which could be adjusted for beam direction, band width and broadcast frequency. The simpler FM-8 and FM-6 models followed at $50 and $30. Unfortunately, BIC has gone bankrupt. However, some outlets still may have some of the excellent Beam Boxes, heavily discounted. The other antennas should be obtainable at prices at least 20 percent below list.