Satellite-based communication systems have been used mainly for the transmission of telephone conversations and television broadcasts. Now satellite-based communication systems are being used to transmit radio broadcasts. In particular, the radio industry has recognized that satellite transmission of radio broadcasts allows listeners in cars, trucks, boats, and other vehicles to receive desired radio programming beyond the relatively limited geographic range associated with standard AM and FM radio broadcasting. In essence, broadcast stations function to create, purchase or otherwise acquire program material, often referred to as content and to broadcast such program material. The broadcast station's goal is to provide program material which is of interest to radio listeners in order to motivate radio listeners toward selection of the station's programming. Historically radio broadcasting started with terrestrial stations using low transmission frequencies with AM (amplitude modulation). Due to its analog narrowband characteristics, susceptibility to interference and propagation variability, AM terrestrial stations cannot transmit high audio quality broadcasts nor, beyond a local area, provide reliable wide geographical coverage. Subsequently, terrestrial radio stations using higher transmission frequencies with FM (frequency modulation) were implemented. These transmit much better quality audio programs, but each terrestrial FM station provides only local geographical coverage and the signal is analog. There are requirements in large countries throughout the world to provide high audio quality, multiple program radio broadcasts. In recent years, a satellite broadcasting system in which signals including audio and video information are transmitted from a broadcasting satellite for broadcasting has been in wide use.

Satellite digital audio radio service (SDARS) is a satellite-based service that broadcasts audio entertainment to fixed and mobile receivers. Satellite radio has the ability to improve terrestrial radio's potential by offering a better audio quality, greater coverage and fewer commercials. SDARS offer digital radio service covering a large geographic area. Satellite-based digital audio radio services generally employ either geo-stationary orbit satellites or highly elliptical orbit satellites that receive uplinked programming, which, in turn, is re-broadcasted directly to digital radios in vehicles on the ground that subscribe to the service. SDARS also use terrestrial repeater networks via ground-based towers using different modulation and transmission techniques in urban areas to supplement the availability of satellite broadcasting service by terrestrially broadcasting the same information. The reception of signals from ground-based broadcast stations is termed as terrestrial coverage. The satellite transmission may be from one or more satellites and from one or more terrestrial repeaters of the satellite transmission in areas where the terrain or man-made structures prohibit good visibility from the automobiles to the satellites. The transmissions from the satellites containing the radio programs are today at frequencies between about 300 MHZ and about 4000 MHZ which are much higher in frequency than those used today for transmission of radio programs such as amplitude modulation (AM) transmission or frequency modulation (FM) transmission. An SDARS system is expected to provide approximately one-hundred channels of music, news, sports, ethnic, children's and talk entertainment on a subscription-based service and may include other services, such as email and data delivery.

In satellite radio systems, a broadcast studio generates analog audio signals much the same as a conventional radio station studio does. For example, an announcer provides real-time narration, and then typically plays music selections from a library of CD music albums. The analog signals are converted to a digital stream of samples, called PCM (pulse code modulation). The conversion is performed for real-time voice or live music performances by passing the analog signals to an A/D (analog-to-digital converter). The digital audio data is then passed to a satellite ground station for transmission to a satellite on its radio frequency uplink carrier. The data can be compressed to save bandwidth and other system resources. The satellite receives the signal from the ground station and retransmits it to the area on the earth's surface where radio reception is desired. The user's receiver decompresses the digital data, and converts it back to analog signals (one for each stereo channel) with a DAC (digital-to-analog converter), for subsequent amplification and listening through loudspeakers. In this receiver, the analog reception signal is mixed down into an intermediate frequency signal by a mixer, will be band-limited with an analog bandpass filter, sampled, analog-to-digital converted and multiplied with complex signal of an oscillator in at least one digital signal processor. In various SDARS systems, a synchronization signal, contained within a received signal, is typically utilized by an earth-based receiver to determine the starting point for digital data framing. In systems that have a terrestrial bandwidth that includes multiple ensembles, each ensemble may include a narrowband synchronization signal that is susceptible to loss due to selective fading at the synchronism frequency.

The use of satellites to broadcast radio programs for reception in automobiles, trucks, vans and other mobile platforms has been widely implemented. In order to receive satellite broadcasts, vehicles must be equipped with proper antennas and receivers. In a satellite radio receiving system, when a receiver is provided in a vehicle, the location of the receiving antenna is crucial. Satellite digital audio radio system (SDARS) antennas communicate radio frequency (RF) signals with one or more satellites. The SDARS antennas are generally required to be positioned in a substantially unobstructed view of one or more satellites to communicate signals therebetween. The SDARS antenna is required to have satellite and terrestrial coverage with reception quality determined by the service providers, and each vehicle subscribing to the digital service generally includes a digital radio having a receiver and one or more antennas for receiving the digital broadcast. Unlike GPS antennas which track multiple satellites at a given time, SDARS patch antennas are operated at higher frequency bands and presently track only two satellites at a time. The mounting location for SDARS patch antennas makes antenna reception a sensitive issue with respect to the position of the antenna on the vehicle. As a result, SDARS patch antennas are typically mounted exterior to the vehicle, usually on the roof. Because the patch antennas are planar and relatively small, manufactures and consumers tend to prefer the implementation of patch antennas.