Abstract:
A RF wireless modem with an integral antenna. The antenna is a compact, horizontally-polarized, balanced, multi-element, directional antenna with integral balun, constructed on one end of a printed wire board (PWB) and radiating preferably away from the modem circuitry on the remaining portions of PWB. The antenna includes a matching network for matching an impedance of the antenna with an impedance of an unbalanced connection and a balun for transforming a RF transmit signal received from the unbalanced connection into a balanced RF transmit signal. The antenna also includes a radiator for transmitting the balanced RF transmit signal and a reflector for reflecting at least some of the energy of the transmitted signal away from the modem circuitry. The antenna can also include a director for directing the RF transmit signal in a desired direction.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to RF wireless modems for use in a laptop, Portable Digital Assistant (PDA), or similar device and more particularly, to RF wireless modems with integral, compact, horizontally-polarized, balanced, multi-element, directional antenna with integral balun. 
     2. Background 
     Recent advancements in electronics have improved the performance of RF wireless modems. For example, advancements in integrated circuit technology have led to high performance radio frequency (RF) circuits. The RF circuits are used to construct transmitters, receivers, and other signal processing components typically found in RF wireless modems. Also, advancements in integrated circuit technology have led to a reduction in the size of RF circuits, thereby leading to a reduction in the overall size of RF wireless modems. Similarly, advancements in battery technology have resulted in smaller, lighter, and longer lasting batteries used in RF wireless modems. These advancements have resulted in smaller and lighter RF wireless modems that operate for a longer period of time on a single charge. 
     A user of a RF wireless modem must be able to communicate with a wireless communication system&#39;s base station, which can be located in any direction from the user and radiates and receives RF signals that are generally vertically polarized. Historically, this has led to the use of vertically polarized antennas for RF wireless modems and other devices, such as cellular phones, that must communicate with wireless communication system base stations. Engineers have designed vertically polarized antennas ranging from simple quarter-wave vertical whips or monopoles, to vertical dipoles, to ¾ wave and ⅝ wave vertical antennas. Some examples of smaller vertical polarized antennas are the “pillbox” antenna, the inverted F antenna, the vertical polarized current loop antenna, and the vertically polarized patch antenna. Some engineers have also used balanced dipole antennas typically of ½ wavelength long. 
     Portable wireless communication devices such as pagers and cellular phones are used extensively today. For example, one such device is the conventional wireless messaging device, which now gives the user full text capability and makes return phone calls less necessary by providing access to information on anything from meetings for the day to local movie listings to the latest global news update. More elaborate, wireless messaging devices combine the benefits and flexibility of two-way messaging, the ability to run software applications, and personal computer connectivity with the wear-ability and convenience of a conventional wireless messaging device. 
     Electronic computing devices are also extensively used today. These computing devices can be fixed, such as a desk top computer, or portable. Portable computing devices in particular are becoming more and more popular. The portability of new electronic organizers PDAs, for example, combined with their longer battery life, larger memories, and safe storage of information, has caused a growth in popularity of these devices over the past few years. New functions such as the synchronization with a personal information manager has proven a major benefit for users of portable computing devices in both their personal and business lives. 
     Manufacturers of RF wireless modems, manufacturers of electronic computing devices, and wireless communication service providers are teaming up to produce integrated services and products including wireless applications capable of receiving text, numeric, or binary messages, and sometimes allowing clipped and full internet access, via RF wireless modems. These enterprise and consumer applications give electronic computing users the capability to receive wireless e-mail, up-to-the-minute news and stock reports, remote updates on interest rates and financial information, weather warnings, and many other applications yet to be imagined. For example, including a RF wireless modem in a computing device enables web-browsing over wireless network access provided by such current and future carrier technologies such as CDPD, CDMA, GSM, GPRS, UMTS, W-CDMA, Richocet, and other proprietary network technology using either circuit switched or packet switched technology. 
     The combination of portable and semi-portable computing devices and rf wireless modems presents new challenges to the RF engineer. For example, there are several problems that result from the integration of a RF wireless modem into an electronic computing device, such as limited antenna space for the RF wireless modem, the degradation of performance of the RF wireless modem due to electromagnetic interference (EMI) from the electronic computing device, the degradation of the performance of the electronic computing device due to transmitted RF energy from the RF wireless modems, and the degradation of the RF wireless modem receiving circuitry due to the transmitted RF energy from the RF wireless modem in full duplex systems. 
     EMI can affect an electronic system through conduction, radiation, or a combination of both. EMI control is a difficult design aspect for RF wireless modem integration into the electronic computing device, since there are so many combinations of EMI sources in the electronic computing device. Additionally, the very high sensitivity of the RF wireless modem&#39;s receiver and the close proximity of its antenna to the circuitry of the electronic computing device make it very susceptible to EMI. This high noise environment creates receiver desensitization when undesired EMI signals occur at the same frequency as the receive frequency, or at a number of other frequencies sensitive to the receiver circuitry (such as the intermediate frequency). Since the receiver cannot differentiate between the desired and undesired signals, the undesired EMI signal can block out the desired signals to desensitize or lower the sensitivity threshold of the receiver. If the amplitude level of the undesired signal can be lowered enough using EMI control techniques, the receiver&#39;s sensitivity threshold is not degraded or degraded an allowable amount. 
     One way to control EMI is to re-design the electronic computing device with EMI in mind. For example, making the housing of the electronic computing device a shielded box, using a dedicated circuit board layer as the ground-plane, using a ground-plane area underneath the RF wireless modem, or modifying the electronic circuit design to reduce the EMI emissions from the electronic computing device are all advantages approaches to controlling EMI. Since the electronic computing device is usually already in existence, however, and most manufacturers do not want to make changes to their electronic computing device, these type of major design modifications are not desirable. Therefore, the RF wireless modem must be designed to reduced susceptibility to the EMI emissions of the electronic computing device. Further, the RF wireless modem should not cause interference with the computing device, and it should fit within the space limitations of the electronic computing device. 
     SUMMARY OF THE INVENTION 
     The present invention is an RF wireless modem with an integral antenna. Antenna is a compact, horizontally-polarized, balanced, multi-element, directional antenna with integral balun, constructed on one end of a printed wire board (PWB) and radiating preferably away from the modem circuitry on the remaining portions of PWB. 
     In one embodiment, the antenna is a horizontally polarized antenna that includes a matching network for matching an impedance of the antenna with an impedance of an unbalanced connection and a balun for transforming a RF transmit signal received from the unbalanced connection into a balanced RF transmit signal. The antenna also includes a radiator for transmitting the balanced RF transmit signal and a reflector for reflecting at least some of the energy of the transmitted signal away from the modem circuitry. 
     In one aspect of the invention, the maximum area of the antenna is approximately 76.2 mm by 35 mm, and the minimum area of the antenna is approximately 10 mm by 4 mm. 
     In another aspect of the invention, the area of the antenna is approximately 50 mm by 27 mm. 
     This compact spacing allows such an antenna to be included in a wireless modem assembly. As such, in another aspect of the invention the antenna is included in a wireless modem assembly that also includes a processor for encoding a baseband transmit signal and receiving a baseband receive signal and a transceiver for modulating the baseband transmit signal with a RF carrier signal to produce a RF transmit signal and for demodulating a RF receive signal with a RF carrier signal to produce the baseband receive signal. 
     Further features and advantages of this invention as well as the structure of operation of various embodiments are described in detail below with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTIONS OF THE DRAWINGS 
       The forgoing aspects and many of the attendant advantages of this invention will become more readily appreciated by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein: 
         FIG. 1  is a block diagram illustrating a wireless modem; 
         FIG. 2   a  is a perspective illustration of a PCMCIA wireless modem card; 
         FIG. 2   b  is a perspective illustration of the PCMCIA wireless modem card of  FIG. 2   a  plugged into a PCMCIA slot of a laptop computer; 
         FIG. 3   a  is a perspective illustration of a wireless modem in the form of an extended PCMCIA PC card that includes an attached antenna within a plastic enclosure, the attached antenna being an unbalanced “F” type monopole; 
         FIG. 3   b  is a perspective cut-away illustration of the wireless modem of  FIG. 3   a;    
         FIG. 4   a  is a partial schematic illustrating a portion of a first side of a wireless modem PWB card in accordance with one example embodiment of the present invention; 
         FIG. 4   b  is a partial schematic illustrating the opposite side of the wireless modem PWB card of  FIG. 4   a;    
         FIG. 5   a  is a partial schematic illustrating a portion of a first side of a wireless modem PWB card in accordance with a second example embodiment of the present invention; 
         FIG. 5   b  is a partial schematic illustrating the opposite side of the wireless modem PWB card of  FIG. 5   a;    
         FIG. 6   a  is a partial schematic illustrating a portion of a first side of a wireless modem PWB card in accordance with a third example embodiment of the present invention; 
         FIG. 6   b  is a partial schematic illustrating a portion of a first side of a wireless modem PWB card in accordance with a fourth example embodiment of the present invention; 
         FIG. 6   c  is a partial schematic illustrating a portion of a first side of a wireless modem PWB card in accordance with a fifth example embodiment of the present invention; 
         FIG. 6   d  is a partial schematic illustrating a portion of a first side of a wireless modem PWB card in accordance with a sixth example embodiment of the present invention; 
         FIG. 7   a  is a partial schematic illustrating a portion of a first side of a wireless modem PWB card in accordance with a seventh example embodiment of the present invention; 
         FIG. 7   b  is a partial schematic illustrating the opposite side of the wireless modem PWB card of  FIG. 7   a;    
         FIG. 8  is a partial schematic illustrating a portion of a first side of a wireless modem PWB card in accordance with a eighth example embodiment of the present invention; 
         FIG. 9   a  is a partial schematic illustrating a portion of a first side of a wireless modem PWB card in accordance with an ninth example embodiment of the present invention; 
         FIG. 9   b  is a partial schematic illustrating the opposite side of the wireless modem PWB card of  FIG. 9   a;    
         FIG. 10   a  is a plot of a measurement of the noise from a vertically polarized antenna minus the noise from an antenna of the present invention from 50 MHz to 2.8 GHz. 
         FIG. 10   b  is a plot of a measurement of the noise from a vertically polarized antenna minus the noise from an antenna of the present invention from 1.8 GHz to 2.0 GHz. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     1. Wireless Modems 
       FIG. 1  illustrates the basic components of a wireless modem  100 . Wireless modem  100  includes a processor  102 , a transceiver  104 , balun and matching network  116  and an antenna  118 . Processor  102  encodes and decodes baseband information signals. Encoded baseband information signal are coupled to transceiver  104 , where they are converted to RF transmit signal. The RF transmit signals are coupled to antenna  118 , via balun and matching network  116 . This is the transmit path for modem  100 . Conversely, RF energy received by antenna  118  is coupled, as a RF receive signal to transceiver  104  via balun and matching network  116 . Transceiver  104 , converts RF receive signals to baseband signals, which are coupled to processor  102 , where they are decoded. This is the receive path for modem  100 . 
     Processor  102  is often referred to as a baseband processor, because it encodes and decodes the baseband signals. Typically, a processor  102  will comprise a plurality of circuits/components. For example, a typical processor  102  can include Analog-to-Digital Converters (ADCs) for converting baseband signals received from transceiver  104  to digital information signals, and Digital-to-Analog Converters (DACs) for converting digital information signals to baseband signals that are sent to transceiver  104 . A typical processor  102  can also include a decoder/encoder for encoding and decoding the digital information signals. The decoded digital information is typically sent to a processor core that can interpret the information and function accordingly. Such a processor core may be a microprocessor, microcontroller, or DSP. The processor core can also control the operation of transceiver  104 . There are other circuits/components that can be included in processor  102 . Moreover, any of the components may be implemented as standalone components separate from processor  102 . 
     Transceiver  104  is typically split into a transmit and receive path. The transmit path comprises a modulator  108  that modulates baseband signals from processor  102  with an RF carrier  110  in order to generate an RF transmit signal. RF carrier  110  is a sinusoidal carrier signal with a frequency equal to that required by the communication channel used by modem  100  to communicate with the base station. The transmit path of transceiver  104  may also include a Power Amplifier (PA)  114 . PAs are typically key components in any high frequency RF transmitter design. This is because RF transmitters typically require high output power to compensate for path losses and to achieve satisfactory signal levels at antenna  118 . 
     The receive path of transceiver  104  comprises a demodulator  106  that modulates a received RF signal with RF carrier  110  in order to remove the carrier and extract the baseband information signal. The receive path may also include a Low Noise Amplifier (LNA). The RF signals received by antenna  118  are typically at very low signal levels. Therefore, a LNA is required in order to amplify the signal level, but not introduce noise that could swamp the low level received signal. 
     The receive and transmit paths are typically duplexed over a common connection  120  to antenna  118 . The impedance of connection  120 , however, needs to match the impedance of antenna  118  for antenna  118  to transmit the RF transmit signal efficiently. If the impedance is not matched, then RF energy will be reflected back in the opposite direction when a transmit or receive RF signal reaches connection  120 . Therefore, the matching network portion of balun and matching network  116  can be included in order to match the impedance between connection  120  and antenna  118 . Typically, for example, connection  120  will have impedance of 50 ohms. Therefore, the matching network needs to adjust the impedance of antenna  118  to be reasonably close to 50 ohms. 
     Connection  120  is often an unbalanced connection; however, antenna  118  typically requires a balanced signal. Therefore, the balun portion of balun and matching network  116  can be included in order to balance the RF transmit signal received from transceiver  104  through unbalanced connection  120 . A balun is a wideband transformer capable of matching a balanced line, such as a twin lead, to an unbalanced line, such as a coaxial cable. 
     A common type of antenna  118  used for wireless communication is the half-wave dipole. A half-wave dipole is simply a straight conductor with a length that is electrically one half the transmission wavelength. Generally, a feed line is attached at the middle of the dipole at right angles to its length. Dipole antennas of electrical lengths shorter than one half the wavelength can also be used. For example, a quarter wave unbalanced vertical antenna is often used in smaller, portable devices. 
     As mentioned, there is a trend towards the integration of RF wireless modems into both portable and fixed types of electronic computing devices. For example,  FIG. 2   a  is a perspective illustration of an extended PCMCIA wireless RF Modem  210  that is designed to be plugged into a PCMCIA slot connector  230  within host computer system  200 . In  FIG. 2   a , the host computer system is a laptop  200 . Modem  210  is shown with an external attached, vertically polarized, monopole antenna  220 .  FIG. 2   b  is a perspective illustration showing modem  210 , with its antenna  220 , fully inserted into PCMCIA slot  230  within laptop  200 . It should be noted that the term “extended” means that a portion of the card still sticks out beyond the edge of the computer even when fully inserted as shown in  FIG. 2   b.    
     The externally attached antenna  220  of  FIGS. 2   a  and  2   b  can be problematic. For example, it may interfere with a user&#39;s ability to use the keyboard of laptop  200 , and it can be susceptible to damage due to its prone position. In contrast,  FIGS. 3   a  and  3   b  illustrate a PCMCIA RF wireless modem  300  with integrated antenna  360 . Antenna  360  is within a plastic enclosure  320  and is mounted within the extended portion  370  of modem  300 . Antenna  360  may, for example, be an unbalanced “F” type monopole, as available from Rangestar of Aptos, Calif. In  FIG. 3   b , the plastic enclosure  320  and some of the external casing  330  of the PCMCIA card  300  has been cut away for viewing of the unbalanced “F” type monopole antenna  360  mounted on an internal Printed Wiring Board (PWB)  340 . An area  350  around antenna  360  has been cleared of any metal conducting material. 
     Antenna  360  of RF wireless modem  300  is still vertically polarized, however, as per the industry standard. Therefore, antenna  360  and modem  300  are still susceptible to significant interference from a computing device, such as device  200 , in which modem  300  is installed. In addition, antenna  360  may cause significant interference with a computing device in which it is installed. 
     2. Preferred Embodiments 
     To overcome these problems, the system and methods for a wireless modem assembly use an antenna design that is integrated into a PWB of a wireless modem assembly. This approach allows for a compact, low profile antenna design. Moreover, the systems and methods for a wireless modem assembly use a horizontally polarized antenna to reduce interference with and interference from the computing device in which the wireless modem is installed. 
       FIG. 4   a  is a partial schematic illustrating a portion of a first side of a wireless modem PWB card  402  with an integral antenna  400  in accordance with one embodiment of the systems and methods for a wireless modem assembly. Thus, antenna  400  is part of a wireless modem PWB card  402  that comprises a processor (not shown), such as processor  102 , and a transceiver (not shown), such as transceiver  104 . Antenna  400  comprises three elements, a director  410 , a radiator  420 , and a reflector  450 . Radiator  420  is a dipole that is driven at approximately its midpoint by a balanced RF transmit signal. Typically, a dipole antenna radiates energy on all sides perpendicular to the long access. Therefore, radiator  420  will radiate RF energy both toward reflector  450  and toward director  410 . The radiated energy going toward reflector  450 , however, will be heading toward the computing device in which wireless modem PWB  402  has been installed. This is undesirable, because the radiated energy would likely cause interference with the computing device. Reflector  450  reflects at least some of this energy, however, thereby reducing any interference with the computing device. 
     Reflector  450  also serves another important function. The energy reflected by reflector  450  is redirected toward the front of radiator  420 , i.e., toward director  410 , forming a directional lobe. Therefore, antenna  400  is a directional antenna that transmits RF energy in a horizontal radiation pattern away from the wireless device in which the wireless modem PWB  402  is installed. 
     Depending on the spacing between radiator  420  and reflector  450 , the use of reflector  450  can also result in a certain amount of directional gain for antenna  400 . The spacing of each element of antenna  400  is discussed more fully below. 
     Director  410  also helps to direct radiated energy from radiator  420  away from the computing device in which the wireless modem PWB  402  is installed. By spacing ( 455 ) director  410  a distance that is sufficiently close to radiator  420 , near-field coupling from radiator  420  can cause current to flow in director  410 . The current can cause director  410  to radiate as well. The energy radiated by director  410  combines with the energy radiated by radiator  420  to form a directional lobe that is directed away from the computing device. 
     Radiator  420  is approximately an electrical half-wavelength at a design frequency f d , with corresponding wavelength λ d , although it could be physically shorter than a half-wavelength and still operate satisfactory with proper loading and impedance matching. Director  410  is preferentially electrically resonate at a higher frequency than f d  and is typically 5 to 30 percent electrically shorter than radiator  420 . 
     Reflector  450 , works with director  410  and radiator  420  to bias the emitted radiation away from PWB  402 . The spacing between the director  410  and radiator  420  is labeled  455  and is measured as the area of non-conducting material  460  between the elements. The spacing between radiator  420  and reflector  450  is labeled  456  and is measured as the area of non-conducting material  462  between the elements. Radiator  420  is closely spaced ( 456 ) relative to reflector  450  at a distance that is preferably between 0.01 times λ d  and 0.1 times λ d . Director  410  is also closely spaced ( 455 ) relative to radiator  420 , towards the edge of PWB  402 , at a distance that is preferably between 0.01 times λ d  and 0.1 times λ d . This close, compact, spacing allows for a directional radiation pattern without antenna  400  being too large for an integral design. 
     Preferably, the frequency limits for antenna  400  are from a minimum of 300 MHz to a maximum of 30 GHz. 
     Antenna  400  includes an integrated balun and matching network  425  for interfacing signals from a transceiver (not shown) to radiator  420 . A top half of balun and matching network  425   a  for radiator  420  is shown as a “U” shaped feature in  FIG. 4   a . In this implementation, the bottom of the “U” is electrically connected to reflector  450 . For all of the implementations described in this specification and that use a “U” shaped balun and matching network, the bottom of the “U” is electrically connected to the closest reflector. One may, however, practice the systems and methods for a wireless modem assembly without electrically coupling the bottom of the “U” shaped balun to the nearest reflector. For example, other balancing and matching schemes may be used, such as RF transformers, delta and gamma feeds, and discrete baluns to name a few. 
     The area occupied by antenna  400  is determined by width  492  and extension  490 . The maximum area for antenna  400  occurs when width  492  is equal to or less than approximately 76.2 millimeters (mm) and extent  490  is equal to or less than approximately 35 mm; however, to have a reasonable efficiency, antenna  400  should have a width  492  that is at least approximately 10 mm and an extent  490  that is at least approximately 4 mm. Preferably, width  492  is approximately 50 mm and extent  490  is approximately 27 mm. 
     The above limits for the spacing of the elements, the antenna width and extent, the electrical antenna element size, and the antenna element construction techniques are common and apply to all of the implementations described in this specification. 
       FIG. 4   b  is a partial schematic illustrating a portion of the opposite side, of the modem PWB  402 . The dashed lines indicate the position of director  410 , radiator  420 , and reflector  450  on the first side of PWB  402 . A second part of balun and matching circuit  425   b  is shown, and is fed by feed line  430 . Feed line  430  connects to a common RF transmit and RF receive connection (not shown), such as connection  120 , on PWB  402 . 
     All of the elements of antenna  400  are formed of conducting material directly on PWB  402  during the normal PWB bare-board manufacturing. The spaces between the elements, such as  460  and  462 , are areas that are free from conducting material. Further, reflector  450  comprises a top and bottom portion  450   a  and  450   b , respectively and, for antenna  400 , reflector  450  is actually a ground plane that is included on PWB  402 . 
       FIG. 5   a  is a partial schematic illustrating an alternative implementation of a wireless modem PWB  502  with an integral antenna  500 . Antenna  500  comprises three elements, a director  510 , a radiator  520 , and a reflector  550 . In the implementation of  FIG. 5   a , director  510  and radiator  520  extend around the edges of PWB  502 . Director  510  and radiator  520  do not form a closed loop, however. Rather,  FIG. 5   b  shows a first gap  512  that exists between the ends of the wrap around director  510  and a second gap  513  between the ends of radiator  520 . Moreover, spacing between the edges of director  510  and radiator  520  and between radiator  520  and reflector  550  are limited by the same constraints as describe with respect to antenna  400 . 
     Preferably, director  510  and radiator  520  wrap around the edge of PWB  502  and there are no internal conducting vias that join the two sides of elements  510  and  520 . 
     Reflector  550  also comprises two sides  550   a  and  550   b  as does balun and matching network  525 . The top side,  525   a , of the balun and matching network is connected to reflector  550   a , and the bottom side  525   b  is by feed line  530 . Feed line  530  is connected to a common RF receive and RF transmit connection (not shown). 
     The dotted lines shown in  FIG. 5   b  show the position of antenna  500  elements with respect to the second side of PWB  502 . The insulating dialectric open areas on PWB  502  are indicated by the blank spaced on PWB  502 , one of which is labeled on each side as  560   a  and  560   b , respectively. 
       FIGS. 6   a ,  6   b ,  6   c , and  6   d  illustrate alternative implementations of integral antennae  600   a ,  600   b ,  600   c , and  600   d , respectively, in accordance with the systems and methods for a wireless modem assembly. Each antenna  600   a ,  600   b ,  600   c , and  600   d  allows for a lower operating frequency than that obtainable with antenna  400  of  FIG. 4   a . The spacing between antenna elements, however, are still constrained to the same limits as describe with respect to antenna  400 . Only the first side of a PWB is shown for each antennae  600 , the opposite sides being similar in construction to that shown in  FIG. 4   b.    
       FIG. 6   a  is a partial schematic illustrating a portion of one side of a wireless modem PWB  602   a  with an integral antenna  600   a . Antenna  600   a  again comprises three elements, where two of the elements, a director  610   a  and a radiator  620   a , are linearly loaded by folding back the conducting material comprising these elements in the manner illustrated in  FIG. 6   a . Reflector  650   a  operates as in the previously discussed implementations. Insulating space is labeled as  660   a  and a portion of a balun and matching network  625   a  is shown and is connected to reflector  650   a.    
     In  FIG. 6   b , on the other hand, two of antenna  600   b  elements, a director  610   b  and a radiator  620   b , are formed in a fan-shape to help lower and broaden the frequency response of antenna  600   b . The dimensions of the fan shape will depend on the desired frequency response. 
     In  FIG. 6   c , a director  610   c  and radiator  620   c , are linearly loaded by forming the conductive material that makes up each element into a zig-zag pattern as illustrated. There can be great variation in the exact zig-zag pattern depending on the requirements of specific implementations. The pattern illustrated in  FIG. 6   c  is, therefore, by way of example only. 
     Finally, in  FIG. 6   d , inductors  670   d ,  680   d , and  690   d  mounted on PWB  602   d  load a director  610   d  and radiator  620   d . Loading by inductors allows efficient operation of antenna  600   d  at a frequency that is lower than the physical length of radiator  620   d  would otherwise allow. 
       FIG. 7   a  illustrates another alternative implementation of a wireless modem PWB  702  comprising an integral antenna  700 . In this alternative implementation, antenna  700  comprises an additional reflector  727 . Ground plane  750  of PWB  702  still acts as a reflector, however. In fact, the systems and methods for a wireless modem assembly can be implemented with as many reflectors as desired. Similarly, a plurality of directors can also be used. It should also be noted that the reflector or director can be omitted if required by a particular implementation. 
       FIG. 7   b  illustrates the opposite side of wireless modem PWB  702 . The dotted lines indicate the positions on the first side of PWB 702  of elements  710 ,  720 , and  727 , respectively. 
       FIG. 8  is a partial schematic illustrating a portion of one side of a wireless modem PWB  802  comprising an integral antenna  800  in still another alternative implementation of the systems and methods for a wireless modem assembly. Again, antenna  800  comprises three elements. Here, however, director  810  and radiator  820  contain two traps  870 , and  880 , respectively. Traps  870  and  880  make antenna  800  resonate on two different frequency bands and are formed of an equivalent parallel inductor and capacitor. The parallel inductor and capacitor are tuned to resonate at the high frequency band of antenna  800  and to offer high impedance to a higher frequency RF transmit signal. Effectively, traps  870  and  880  electrically disconnect the ends of director  810  and radiator  820  making them appear electrically shorter when radiator  820  is driven by a higher frequency RF transmit signal. Traps  870  and  880  also provide loading of the full length of antenna  800  so that it can still resonate at the lower frequency band as well. With this approach, a single antenna  800  can, for example, work at the AMPS frequency (low frequency band) and the PCS frequency (high frequency band). 
       FIGS. 9   a  and  9   b  illustrate a ninth and final alternative implementation of the systems and methods for a wireless modem assembly.  FIG. 9   a  is a partial schematic illustrating a portion of a first side of a wireless modem PWB  902  comprising an integral antenna  900 . Integral antenna  900  comprises three elements, a director  910 , a radiator  920 , and a reflector  927 . Area  960  and the other blank areas in  FIG. 9   a  indicate that those areas are free from conducting material. A balun and matching network  925   a  for radiator  920  is shown as a “U” shaped feature in the drawing. The bottom of the “U” is electrically connected to the reflector  927 . The spacing between director  910  and radiator  920  is labeled  955  and is measured as the area of non-conducting material between the two elements. The spacing between radiator  920  and reflector  927  is labeled  956  and is measured as the area of non-conducting material between the two elements. All of the elements of the of antenna  900  are formed of conducting material directly on PWB  902  during the normal PWB bare-board manufacturing process. 
     Radiator  920  is approximately an electrical half-wavelength at a design frequency f d , with corresponding wavelength λ d , although it could be physically shorter than a half-wavelength and still operate satisfactory with proper loading and with impedance matching. Director  910  is preferably electrically resonate at a higher frequency than f d  and is preferably 5 to 30 percent electrically shorter than radiator  920 . 
     Reflector  927  works with director  910  and radiator  920  to bias the emitted radiation away from PWB  902 . Reflector  927  is connected to the ground-plane  950   a  along its length, thus working similar to reflector  450 . Radiator  910  is closely spaced ( 956 ) with respect to reflector  927 , at a distance that is preferably between approximately 0.01 times λ d  and approximately 0.1 times λ d . Director  910   a  is also closely spaced  955  with respect to radiator  920 , towards the edge of PWB  902 , at a distance that is preferably between approximately 0.01 times λ d  and approximately 0.1 times λ d . This close, compact, spacing allows for a directional radiation pattern without antenna  900  being too large for an integral design. 
     The frequency limits for antenna  900  are preferably from a minimum of 300 MHz to a maximum of 30 GHz. 
     A width  992  and an extension  990  describe the overall size of antenna  900 . At a maximum, the width  992  is equal to or less than approximately 76.2 mm and the extent  990  is equal to or less than approximately 35 mm; however, to have a reasonable efficiency, antenna  900  should have at least a width  992  of approximately 10 mm and an extent  990  of approximately 4 mm. Preferably, the width  992  is approximately 50 mm and the extent  990  is approximately 27 mm. 
       FIG. 9   b  shows the opposite side of PWB  902 . As can be seen, director  910 , radiator  920 , and reflector  927  comprise conducting material on both the top and bottom of PWB  902 . The top portion of each element is connected to the lower portion by multiple conducting vias (not shown) in PWB  902 . Preferably, PWB  902  actually comprises a plurality of inner layers (not shown), where each inner layer comprises antenna elements that are replicas of the elements on the top layer, and where all of the layers are electrically connected through conducting vias. 
     A balun and matching circuit  925  is fed through a single pole double throw RF connector  973  that is mounted between a bottom portion of balun and matching network  925   b  and a feed line  930 . Feed line  930  connects to a common RF transmit and RF receive connection (not shown) on PWB  902 . RF connector  973  allows connecting test and measurement instrumentation to the wireless modem assembly and disconnects antenna  900  from the circuit when a male test connector (not shown) is inserted. 
     The radiation patterns from each antenna described is polarized in the plane of the respective PWBs and the radiation and or receive pattern is biased away from the circuitry on each of the respective PWBs. Each antenna reduces interference the receive circuitry of the respective wireless modem assemblies caused by the transmit portion of the respective modem assemblies in full duplex communications. Moreover, each antenna reduces the interference with the wireless modem assemblies caused by the operation of the respective computing device, such as a personal digital assistant (PDA) or OEM equipment, in which a wireless modem assembly is installed. In addition, each antenna reduces the interference to the respective computing device caused by the operation of the wireless modem assembly. 
     3. Test Results 
       FIG. 10   a  is a plot  1010  of a measurement of the noise from a presently used, vertically polarized antenna minus the noise from an antenna designed in accordance with this specification. The range of plot  1010  is from 50 MHz to 2.8 GHz. The difference is plotted in dBm/3 MHz. Vs frequency. The values plotted indicate that for a very wide range of frequencies, the vertically polarized antenna picks up a substantial amount more noise than a horizontal antenna designed in accordance with this specification. 
       FIG. 10   b  is a plot  1020  of a measurement of the noise from a presently used, vertically polarized antenna minus the noise from an antenna designed in accordance with this specification, where the range of plot  1020  is from 1.8 GHz to 2.0 GHz, i.e., including the PCS band. The difference is plotted in dBm/3 MHz. Vs frequency. The values plotted indicate that the vertically polarized antenna also picks up a substantial amount more noise for a range of frequencies covering the PCS band. 
     Picking up less noise is not necessarily enough to ensure adequate operation of the wireless modem assembly. In the following experiment, the noise, the signal, and the SNR are measured while receiving a PCS signal from a PCS base station. 
     Measurements were taken with 3 antennas V 1 , V 2 , and H 1  to illustrate the improvements in Signal To Noise Ratio (SNR) obtained with a wireless modem assembly designed in accordance with this specification. Antenna V 1 , not shown but similar to antenna  220  in  FIG. 2   a , is a vertical quarter wave whip antenna, mounted on a first corner a PCMCIA card. A local PCS band base station was used to provide signal at around 1931 MHZ and a noise measurement was made adjacent the CDMA signal on a “quiet” frequency. The average signal strength, the average noise strength, and the SNR was measured for 8 angular rotations about a vertical axis centered on antenna of 0°, 45°, 90°, 135°, 180°, 225°, 270°, and 315° degrees with 0 degrees being magnetic north of the laptop on a desk. The test was repeated with antenna V 2 , not shown but also similar to  220  in  FIG. 2   a . Antenna V 2  was mounted on the opposite side of a PCMCIA card relative to V 1 , with the card inserted into a PCMCIA slot on a PC laptop computer. Like V 1 , antenna V 2  is a vertical quarter wave whip antenna. The test was repeated one more time. But this time with a prototype antenna H 1 , not shown but similar to antenna  900  shown in  FIG. 9   a.    
     Table 1 presents the signal measurements, the units are dBm/300 KHz. Table 2 presents the noise measurements, the units are dBm/300 KHz. Table 3 presents the SNR measurements, the units are dBm/300 KHz. Table 3 also includes the average of the SNR over the 8 angles. 
     
       
         
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                   
                 V1- 
                 V2- 
                 H1- 
               
               
                   
                   
                 Signal 
                 Signal 
                 Signal 
               
               
                   
                   
                 dBm/300 
                 dBm/300 
                 dBm/300 
               
               
                   
                 Angle 
                 Khz 
                 Khz 
                 Khz 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 0 
                 −73.0 
                 −75.5 
                 −74.7 
               
               
                   
                 45 
                 −73.3 
                 −72.6 
                 −79.0 
               
               
                   
                 90 
                 −75.9 
                 −77.8 
                 −74.0 
               
               
                   
                 135 
                 −78.0 
                 −74.2 
                 −76.7 
               
               
                   
                 180 
                 −76.0 
                 −69.5 
                 −74.3 
               
               
                   
                 225 
                 −74.4 
                 −73.2 
                 −71.0 
               
               
                   
                 270 
                 −76.8 
                 −74.8 
                 −71.3 
               
               
                   
                 315 
                 −75.7 
                 −73.5 
                 −75.0 
               
               
                   
                   
               
             
          
         
       
     
     
       
         
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                   
                 TABLE 2 
               
               
                   
                   
               
               
                   
                   
                 V1-Noise 
                 V2-Noise 
                 H1-Noise 
               
               
                   
                 Angle 
                 dBm/300 Khz 
                 dBm/300 Khz 
                 dBm/300 Khz 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 0 
                 −79.5 
                 −79.2 
                 −82.2 
               
               
                   
                 45 
                 −79.5 
                 −80.6 
                 −83.0 
               
               
                   
                 90 
                 −79.6 
                 −81.7 
                 −84.0 
               
               
                   
                 135 
                 −80.1 
                 −81.5 
                 −81.0 
               
               
                   
                 180 
                 −80.3 
                 −78.8 
                 −85.4 
               
               
                   
                 225 
                 −80.4 
                 −80.0 
                 −82.6 
               
               
                   
                 270 
                 −79.9 
                 −79.5 
                 −82.0 
               
               
                   
                 315 
                 −79.8 
                 −80.1 
                 −81.7 
               
               
                   
                   
               
             
          
         
       
     
     
       
         
               
               
               
               
             
               
               
               
               
             
               
               
               
               
             
           
               
                 TABLE 3 
               
               
                   
               
               
                   
                 V1-SNR 
                 V2-SNR 
                 H1-SNR 
               
               
                 Angle 
                 dBm/300 Khz 
                 dBm/300 Khz 
                 dBm/300 Khz 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 0 
                 6.5 
                 3.7 
                 7.5 
               
               
                 45 
                 6.3 
                 8.0 
                 4.0 
               
               
                 90 
                 3.7 
                 3.9 
                 10.0 
               
               
                 135 
                 2.0 
                 7.3 
                 4.3 
               
               
                 180 
                 4.0 
                 9.3 
                 11.1 
               
               
                 225 
                 5.6 
                 6.8 
                 11.6 
               
               
                 270 
                 3.2 
                 4.7 
                 10.8 
               
               
                 315 
                 4.3 
                 6.6 
                 6.7 
               
             
          
           
               
                 AVERAGE =&gt; 
                 4.8 
                 6.7 
                 9.1 
               
               
                   
               
               
                 Note: averages calculated by converting the signal and noise values to linear scale, taking the ratio, averaging, and converting back to log scale. 
               
             
          
         
       
     
     As is seen in Table 3, the use of the H 1  antenna improves the SNR ratio by a significant amount over antennae V 1  and V 2 . While this measurement was taken in a receive mode, it is anticipated that a wireless modem assembly with an antenna such as H 1  would also perform better when transmitting a signal to the base station. 
     While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example only, and not limitation. Thus, the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.