**1. Introduction**

224 VLSI Design

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In this research, we developed a dual antenna array for the household reception of openly analogical television (TV) frequencies. This array was designed on Flame Retardant-4 (FR-4) as substrate, in order to obtain a low cost prototype.

The interest in this area is because of the fact that the openly TV is one of the most important communication media in our country. From information supplied in 2009 in the National Survey over availability and use of Technologies, it reveals that the 72.8% of the population uses the services of the openly TV (Instituto Nacional de Estadística, Geografía e Informática [INEGI], 2009). A TV can be found in almost all homes of the country, but only 13.6% correspond to digital technology, while only a half of homes with a digital TV requires signal payment. The availability of TVs in Mexican homes in 2010 remained without severe changes (INEGI, 2010).

Since the operation frequencies ranges are not so high, and then the antenna sizes, obtained directly from the design equations are very large. Therefore, the scaling is a necessary step in order to reduce the antenna sizes to achieve its easy manipulation.

As it is well-known, a very simple common example of antennas used for household reception of TV is the Yagi-Uda (or Yagi) array, where the length of the dipoles established the phase of the individually received signals. An example of a commercial Yagi-Uda antenna designed for channels 2-13 can be found in (Balanis, 2005). The TV transmission has the polarization vector in the horizontal plane so that the array must also be horizontal (Melissinos, 1990).

The evolution of the antennas designed in order to improve the openly TV reception has notably changed in the last years, in such a way, for outdoor use it is possible to find the large aerial antennas, fixed or with an integrated rotor, under different geometries, such as

Low Cost Prototype of an Outdoor Dual Patch Antenna

depending of the corresponding Mexican states.

Table 1. Digital assigned channels as mirrors.

5, some concluding remarks are given.

**2. Antenna array design** 

For the patch width:

Array for the Openly TV Frequency Ranges in Mexico 227

MHz to 216 MHz. Some channels are divided between the two most important television companies as follows: the broadcast channels of Televisa are 2, 4, 5 and 9 (a repetition of channel 2); and the corresponding of TV Azteca are 7 and 13 (channels in operation in D.F. in 2006 (Jalife & Sosa, 2007)). Some channels can be transmitted in different frequencies

In addition, in each Mexican state, there are additional channels by concession, for example in Morelos, channel 6 corresponds to the Instituto Politécnico Nacional, 3 to the Government of the Morelos State, 11 to Radio Televisora de Mexico Norte S. A. de C. V., 28 to TV Azteca, and 22 to the Presidencia Municipal de Zacatepec (Comisión Federal de Telecomunicaciones

In our country, for some analogical active channels, temporary it is assigned an additional channel (mirror) to transmit the same information, but with a digital format, until the transition to the digital terrestrial television in Mexico concludes. The last period of transition was planned from 2019 up to 2021, but recently it has been established until December 31, 2015. The temporary digital channels assigned are shown in Table 1. The

TV analogical channel TV digital channel

In this works, our interest is focused in a patch antenna array prototype for openly TV frequency ranges in Mexico, with polarization diversity, for outdoor use. In Section 2, the design of the antenna array will be described and the corresponding simulations will be provided in Section 3. The first tests results are discussed in Section 4, and finally, in Section

Considering only the two current VHF frequency ranges of the openly TV in Mexico, we chose as operation frequency to 71 MHz for the design of the rectangular patch antenna, which will be used as the base of the prototype patch antenna array. This frequency corresponds to the central frequency of the first sub-range of frequency of VHF. The rectangular antenna was

<sup>1</sup> <sup>2</sup> <sup>2</sup>

(1)

*<sup>r</sup> fo* ε<sup>=</sup> <sup>+</sup>

*<sup>c</sup> <sup>W</sup>*

designed using the well-known equations (Balanis, 2005 and Garg et al., 2001):

[COFETEL], 2008). From channels 14 to 83, they correspond to UHF band.

analogical channels will be returned when the transition will be finished.

2 48 4 49 5 50 7 24 9 44 13 25

single dipoles and combinations of Yagi arrays. A decrease in sizes is noted in some cases. An example of design development of antenna for TV transmission for outdoor broadcasts can be found in (Rathod, 2010), at 750 MHz as the center frequency, where the antenna was fabricated on FR-4, with substrate sizes of 40x40 cm2. This antenna was designed for the study of rural areas in India.

For indoor use, there are also several options of relative small sizes, and under different geometries. Recently, new commercial options based on patch or microstrip antennas have been proposed, which can be located on the rear part of the TV display that means, hidden to the user. But there is not available technical information about its design. An UHF planar O-shaped antenna has been proposed and studied (Barir & Hamid, 2010), which was fabricated on FR-4, with a dimension area of 20x20 cm2, with an enough bandwidth to cover Indonesian broadcasters.

Other special case is formed by the antennas for TV reception in cars. In (Neelakanta & Chatterjee, 2003), a V-structure dipole, which is part of the dipole families, has been conceived for the purpose of TV reception (VHF/UHF bands), which gives a directional pattern with horizontal polarization. An active loop antenna suitable as automobile television receiving antenna, for channels 13-62 (from 470-770 MHz in Japan) can be found in (Taguchi et al., 1996).

In (Wang & Lecours, 1999), an antenna array with orthogonal polarization finds applications in Direct Broadcasting Systems (DBS), Personal Communication Services (PCS) and Indoor Communication Systems (ICS). As the current DBS technology uses both horizontal and vertical polarizations, and then the microstrip arrays with orthogonal polarizations are needed. While in PCS and ICS, waves are scattered by the environment and the signal takes several paths from a transmitter to a receiver, with resulting fluctuations in amplitude because of multipath fading effect. To overcome this effect, it is necessary to implement a polarization diversity technique, for which antenna arrays with orthogonal polarizations and very low cross couplings are needed.

On the other hand, it is recognized as a common problem in TV to the multipath reception, where signals from the same station can reach the reception antenna by two or more distinct paths which differ significantly in length (web site: http://www. electusdistribution.com.au/images\_uploaded/tvrecepe.pdf, May 2011).

In (Brown et al., 2007) it was shown that dipoles and other linear antennas can sometimes, although not always, have a large degree of polarization diversity if they have different polarization orientations. A typical configuration of polarization diversity system consists of one transmit and one dual-polarized receive antenna (i.e., maximal diversity order of two) (Kapinas et al., 2007).

Dual linear polarization is characterized by two orthogonal linear polarizations on the same antenna. Dual polarization antennas have the benefit of allowing two signals, with different orientations, to be broadcast or received on the same antenna (Smith, 2008).

#### **1.1 Mexican TV system**

The TV channels in Mexico, in the VHF band are divided in two sub-bands: From 2 to 6, they are in the range from 54 MHz to 88 MHz, and from 7 to 13 are transmitted from 174

single dipoles and combinations of Yagi arrays. A decrease in sizes is noted in some cases. An example of design development of antenna for TV transmission for outdoor broadcasts can be found in (Rathod, 2010), at 750 MHz as the center frequency, where the antenna was fabricated on FR-4, with substrate sizes of 40x40 cm2. This antenna was designed for the

For indoor use, there are also several options of relative small sizes, and under different geometries. Recently, new commercial options based on patch or microstrip antennas have been proposed, which can be located on the rear part of the TV display that means, hidden to the user. But there is not available technical information about its design. An UHF planar O-shaped antenna has been proposed and studied (Barir & Hamid, 2010), which was fabricated on FR-4, with a dimension area of 20x20 cm2, with an enough bandwidth to cover

Other special case is formed by the antennas for TV reception in cars. In (Neelakanta & Chatterjee, 2003), a V-structure dipole, which is part of the dipole families, has been conceived for the purpose of TV reception (VHF/UHF bands), which gives a directional pattern with horizontal polarization. An active loop antenna suitable as automobile television receiving antenna, for channels 13-62 (from 470-770 MHz in Japan) can be found

In (Wang & Lecours, 1999), an antenna array with orthogonal polarization finds applications in Direct Broadcasting Systems (DBS), Personal Communication Services (PCS) and Indoor Communication Systems (ICS). As the current DBS technology uses both horizontal and vertical polarizations, and then the microstrip arrays with orthogonal polarizations are needed. While in PCS and ICS, waves are scattered by the environment and the signal takes several paths from a transmitter to a receiver, with resulting fluctuations in amplitude because of multipath fading effect. To overcome this effect, it is necessary to implement a polarization diversity technique, for which antenna arrays with orthogonal polarizations

On the other hand, it is recognized as a common problem in TV to the multipath reception, where signals from the same station can reach the reception antenna by two or more distinct paths which differ significantly in length (web site: http://www.

In (Brown et al., 2007) it was shown that dipoles and other linear antennas can sometimes, although not always, have a large degree of polarization diversity if they have different polarization orientations. A typical configuration of polarization diversity system consists of one transmit and one dual-polarized receive antenna (i.e., maximal diversity order of two)

Dual linear polarization is characterized by two orthogonal linear polarizations on the same antenna. Dual polarization antennas have the benefit of allowing two signals, with different

The TV channels in Mexico, in the VHF band are divided in two sub-bands: From 2 to 6, they are in the range from 54 MHz to 88 MHz, and from 7 to 13 are transmitted from 174

electusdistribution.com.au/images\_uploaded/tvrecepe.pdf, May 2011).

orientations, to be broadcast or received on the same antenna (Smith, 2008).

study of rural areas in India.

Indonesian broadcasters.

in (Taguchi et al., 1996).

(Kapinas et al., 2007).

**1.1 Mexican TV system** 

and very low cross couplings are needed.

MHz to 216 MHz. Some channels are divided between the two most important television companies as follows: the broadcast channels of Televisa are 2, 4, 5 and 9 (a repetition of channel 2); and the corresponding of TV Azteca are 7 and 13 (channels in operation in D.F. in 2006 (Jalife & Sosa, 2007)). Some channels can be transmitted in different frequencies depending of the corresponding Mexican states.

In addition, in each Mexican state, there are additional channels by concession, for example in Morelos, channel 6 corresponds to the Instituto Politécnico Nacional, 3 to the Government of the Morelos State, 11 to Radio Televisora de Mexico Norte S. A. de C. V., 28 to TV Azteca, and 22 to the Presidencia Municipal de Zacatepec (Comisión Federal de Telecomunicaciones [COFETEL], 2008). From channels 14 to 83, they correspond to UHF band.

In our country, for some analogical active channels, temporary it is assigned an additional channel (mirror) to transmit the same information, but with a digital format, until the transition to the digital terrestrial television in Mexico concludes. The last period of transition was planned from 2019 up to 2021, but recently it has been established until December 31, 2015. The temporary digital channels assigned are shown in Table 1. The analogical channels will be returned when the transition will be finished.


Table 1. Digital assigned channels as mirrors.

In this works, our interest is focused in a patch antenna array prototype for openly TV frequency ranges in Mexico, with polarization diversity, for outdoor use. In Section 2, the design of the antenna array will be described and the corresponding simulations will be provided in Section 3. The first tests results are discussed in Section 4, and finally, in Section 5, some concluding remarks are given.
