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| | Maybe you have buddies and co-workers who mention their lawyer as though it have been properly regular to have one. Even though the expenses of working with a attorney are prohibitive to the common individual, you will find strategies to have authorized associates on retainer for a small part of the price of selecting one in desperate situations. Go through on this page concerning how to locate these legal professionals and the way to set up the partnership.<br><br>Ask for a free of charge consultation. Many legal professionals will offer you a free consultation, so you can have [http://www.youtube.com/watch?v=D3fHaPD5K80 youtube.com/watch?v=D3fHaPD5K80] your queries answered. During the assessment, you may also see in case you are at ease with that legal representative. Usually check out multiple totally free consultation so you have a good mix of lawyers to select from.<br><br>Rule 1 of hiring a legal representative: Ambulance chasers are not so good news. Typically, these are typically cons that could monetarily injured you. Take the initiative to reach out to possible legal professionals and workout your straight to control the problem.<br><br>Come up with a spending budget in relation to investing in legal costs. If you contact an legal professional and are generally earlier mentioned your cost range, try to find someone else. While there is nothing wrong with moving just a little around your financial allowance, you may not would like to select a lawyer you will have problems seeking to pay.<br><br>Make sure that you possess a respectable connections with any lawyer before you make investments any money. You may have to invest a good length of time together with your legal representative, so it is crucial that you choose the one that you don't possess any problems working together with. Spend some time to take a seat with any potential law firms to see if you achieve an effective sense of them.<br><br>Just before your conference with potential lawyers, determine your best target. The first thing to request is whether you need a legal professional. You need a legal professional should you be in the separation and divorce, responsible for a criminal offense or come with an approaching lawsuit. No matter whether you are involved in these types of circumstances or not, you will still might need an attorney or a variety of other legal issues.<br><br>You ought to create a spending budget before you begin looking for a attorney. Review your financial situation and determine what you can manage to invest in a legal representative. You should not permit attorneys learn about your financial budget once you ask for quotes but this is a great strategy to restrict your homework.<br><br>It is essential to discuss service fees with the lawyer at the start, before you sign any deals using them. Discover the fee construction which they use to be sure that you can pay for their providers. Should it be from the price range, then you can certainly check around for a more affordable lawyer.<br><br>Try and complement the business that you just select with the significance of your scenario that you are currently in. Should you be within a critical combine, you will want to have got a large organization on your side. In case you are attempting to surpass a relocating breach, you may get a lawyer that is owned by a lesser firm.<br><br>A good hint to keep in mind if you're contemplating working with a legal professional is always to provide them with all the information since you can. The better [http://www.youtube.com/watch?v=D3fHaPD5K80 youtube.com/watch?v=D3fHaPD5K80] papers and data they already have that pertains to an instance, the higher your odds are of succeeding. If you think a papers may be useless, you attorney may believe normally.<br><br>Although you may have not been in issues or experienced legal needs just before, at this point you know could possibly occur whenever you want. For program legitimate paperwork or acquiring assistance with dealings, it usually helps you to have expert authorized oversight. Take whatever you have discovered in this article and set it to make use of to find the legal support tht you may need. |
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| == Introduction ==
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| [[Image:Antenna, monopole.JPG|thumb|40px|right|Monopole Antenna]]
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| A typical [[monopole antenna]], pictured to the right, has an omni-directional [[Radiation pattern|pattern]] and is limited in its frequency range. Please keep in mind that an omni-directional (see [[omnidirectional antenna]]) radiation pattern applies to the azimuth patterns and does exhibit a [[Null (radio)|null]] at [[zenith]].
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| A monopole antenna can be thought of as a [[dipole antenna]] where one end of the dipole antenna now becomes the ground plane for said monopole antenna. By this line of conceptual thinking, one can easily reach the conclusion that the radiation emanating from a monopole antenna exists in half the space of similar dipole antenna. Therefore, the maximum gain is twice that, or an addition 3dB, of the maximum gain of typical dipole. Hence the nominal value of maximum for a monopole antenna is about 5.15dBi.
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| Stutzman puts is succinctly as follows:
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| :''... A '''monopole''' is a dipole that has been divided in half at its center feed point and fed against a ground plane...''<ref name="Stutzman">Stutzman, Warren L., and Gary A. Theiele. ''Antenna Theory and Design''. 2nd Ed. New York: 1998. ISBN 0-471-02590-9</ref>
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| This article covers one type of dual band blade monopoles. This is the slot inside a monopole. Computational Electromagnetic Modeling (CEM) will be used to give some graphics of operations for a more conceptual understanding.
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| == Theory ==
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| ===Monopoles===
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| Monopole equations can be arrived by inspection of [[dipole antenna]] derivations with the knowledge that all radiation occurs in half the volume when compared to said dipole antenna. This leads to the following equations:
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| ''[[Directivity]]''
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| <math>D_{mono}=\frac{4\pi}{\Omega_{A,mono}}=2D_{dipole}</math><ref name="Stutzman" />
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| This leads directly to the earlier stated maximum gain relation to a dipole by the definition of gain a <math>G=\epsilon D</math> where <math>\epsilon</math> is the antenna radiation efficiency.
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| ''[[Electrical impedance|Impedance]]''
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| <math>Z_{A,mono}=\frac{1}{2}Z_{A,Dipole}</math><ref name="Stutzman" />
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| ''[[Radiation Resistance]]''
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| <math>R_{r,mono}=\frac{1}{2}R_{r,mono}</math><ref name="Stutzman" />
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| As can be seen in section 1 of the linked [[radiation resistance]] article.
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| ====Blade Antennas====
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| A blade antenna is an attempt to create a broader band monopole (when compared to a thin wire monopole). Most blade antennas are [[trapezoid]]al in shape. Variations have been made on this shape for [[aerodynamics|aerodynamic]] purposes and notches have been introduced in order to achieve a better broad band performance. These type of monopole antennas are generally used in aviation for [[Very High Frequency|VHF]] and [[Ultra High Frequency|UHF]] frequency ranges.
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| For more information see the ''Antenna Engineering Handbook''.<ref name="Ant_hndbk">''Antenna Engineering Handbook''. Ed. Richard C. Johnson. Ed. Henry Jasik. 3rd ed. New York: McGraw-Hill 1993. ISBN 0-07-032381-X</ref>
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| ===Slot Antennas===
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| A [[slot antenna]] can be viewed as a dipole with opposite polarization. This is due to the typical feed which sets the orientation of the E-field across the smallest linear dimension of the slot. The following equations can be used to 'translate' a vertical or horizontal slot antenna into its complement (dipole):
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| <math>E_{\theta s} = H_{\theta c} \qquad E_{\phi s} = H_{\phi c} \qquad H_{\theta s} = \,-\frac{E_{\theta c}}{\eta_o^2} \qquad H_{\phi s} = \, -\frac{E_\phi c}{\eta_o^2}</math><ref name="Balanis">Balanis, Constantine A. ''Antenna Theory, Analysis and Design''. 3rd Ed. New Jersey: John Wiley & Sons, INC., 2005. ISBN 0-471-66782-X</ref>
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| Where the subscript S denotes the opening on the screen and the subscript C denotes its complement (a dipole). In addition, <math>\eta = \sqrt{\tfrac{\mu}{\epsilon}}</math> where <math>\mu</math> is the complex [[permeability (electromagnetism)|permeability]] and <math>\epsilon</math> is the complex [[permittivity]] of the medium into which one is radiating. This assumes an unbounded medium. In addition, all of the slot equations assume a screen thickness much less than a wavelength (<math>< \tfrac{\lambda}{10}</math>). If these were not held to be true, fringing and the existence of modes could not be ignored.
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| This is defined by [[Babinet's principle]] and Booker's Extension further expands this
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| principle to include polarization. The simple equations from Babinet's principle are stated on the linked page for which the author has had input.
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| ===Dual Band Antennas===
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| Dual band antennas are not a new idea. For years many manufactures have combined multiple elements to create antennas that operate in two separate bands (do not get this confused with so-called frequency independent antennas such as a [[log-periodic antenna]]).
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| One way to create a dual band blade antenna is to create a slot in a blade antenna that is less than or on the order of <math> \tfrac{\lambda}{10} </math> so that the lower frequency does not 'see' the slot (it is a general rule of thumb that the perturbation created by a discontinuity less than <math> \tfrac{\lambda}{10} </math> on a structure is negligible).
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| == Computational Electromagnetic Modeling (CEM) ==
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| Computational Electromagnetic Modeling (CEM)uses various methods to numerically calculate an antenna pattern.
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| To the untrained eye, this may seem a trivial process. Although, with some research and thought, one will realize that all local structures affect the radiation pattern either by reflection, absorption, refraction, fringing, or being a part of the radiating structure. Some structure which is not local will also cause these items and more including blockage and 're-radiation'. With this in mind, the calculation can become cumbersome.
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| Multiple algorithms exist in CEM. These include but are not limited to Method of Moments (MoM), Finite Element Method (FEM), and Uniform Theory of Diffraction (UTD). Two examples of software packages that use these methods in free-space are [[FEKO]] and WIPL-D. The examples shown here come from WIPL-D. Please keep in mind, these software packages must be used by someone who understands the process and can decide whether the calculated is real or if an error in the model and input data generated false output data (the old adage of garbage in equals garbage out).
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| ===Dual Band Blade Antenna Example===
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| This example will use a design for an approximate frequency for Biomedical Telemetry at 460 MHz and [[GPS]] frequency L1 (1575.42 MHz) in a single package (I hesitate to say a single antenna because there are two radiating elements which would require two baluns for matching). Please keep in mind, these are not match to any transmission line. Therefore the design will not be practical for use. It is only for demonstration purposes.
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| Below you will see the simple used for the simulations. The ground plane is twice the [[wavelength]] at 460 MHz.
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| [[Image:Dual Band Blade Antenna model.jpg|thumb|600px|center|Model used for Simulation]]
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| Below is a comparison of the horizontal radiation patterns at L1 for both the blade and the slot. The slot exhibits the figure 8 dipole pattern with decent gain. While the blade still radiates, the gain is lower and the pattern is very loby creating nulls. Please note, for a larger image, follow the link in each caption or just click on the image (it will be better quality if you click the image).
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| <gallery caption="L1 Horizontal Radiation Patterns" widths="400px" heights="300px" perrow="2"> | |
| Image:Hpol_dual_band_blade_antenna_slot_L1_3D.jpg|Horizontal Polarization Radiation Pattern for the Slot at L1 [[Media:Hpol dual band blade antenna slot L1 3D.jpg|Link]].
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| Image:Hpol_dual_band_blade_antenna_blade_L1_3D.jpg|Horizontal Polarization Radiation Pattern for the Blade at L1 [[Media:Hpol dual band blade antenna blade L1 3D.jpg|Link]].
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| </gallery> | |
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| One will also note the polarization of the two elements. As stated before, the polarization of the slot is due to its feed which is generally across the smallest linear dimension. Hence, this slot is Horizontally polarized with respect to the ground plane and the blade is vertically polarized with respect to the ground plane.
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| <gallery caption="L1 Vertical Radiation Patterns" widths="400px" heights="300px" perrow="2">
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| Image:Vpol_dual_band_blade_antenna_slot_L1_3D.jpg|Vertical Polarization Radiation Pattern for the Slot at L1 [[Media:Vpol dual band blade antenna slot L1 3D.jpg|Link]].
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| Image:Vpol_dual_band_blade_antenna_blade_L1_3D.jpg|Vertical Polarization Radiation Pattern for the Blade at L1 [[Media:Vpol dual band blade antenna blade L1 3D.jpg|Link]].
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| </gallery>
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| Here we are seeing the vertically polarized radiation patters or Vpol for 460 MHz.
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| <gallery caption="460MHz Vertical Radiation Patterns" widths="400px" heights="300px" perrow="2">
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| Image:Vpol_dual_band_blade_antenna_slot_460_3D.jpg|Vertical Polarization Radiation Pattern for the Slot at 460 MHz [[Media:Vpol dual band blade antenna slot 460 3D.jpg|Link]].
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| Image:Vpol_dual_band_blade_antenna_blade_460_3D.jpg|Vertical Polarization Radiation Pattern for the Blade at 460 MHz [[Media:Vpol dual band blade antenna blade 460 3D.jpg|Link]].
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| </gallery> | |
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| Whereas presented here we can see the Hpol radiation pattern for both the blade and slot elements.
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| <gallery caption="460MHz Horizontal Radiation Patterns" widths="400px" heights="300px" perrow="2"> | |
| Image:Hpol_dual_band_blade_antenna_slot_460_3D.jpg|Horizontal Polarization Radiation Pattern for the Slot at 460 MHz [[Media:Hpol dual band blade antenna slot 460 3D.jpg|Link]].
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| Image:Hpol_dual_band_blade_antenna_blade_460_3D.jpg|Horizontal Polarization Radiation Pattern for the Blade at 460 MHz [[Media:Hpol dual band blade antenna blade 460 3D.jpg|Link]].
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| </gallery>
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| ==Conclusion==
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| By the preceding section, it is seen that a dual band blade antenna can be polarity diverse as well as dual band. The bands chosen for this example are relatively close in frequency and give a poor example of the power of such a device, yet it nicely illustrates what can be completed. Given enough real-estate, one can cover two very diverse bands with good coverage and opposite polarization.
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| It also clearly illustrates that the impact of the rectangular slot radiating element is negligible on the radiation pattern of the lower frequency monopole. This is due to the previously mentioned rule of thumb stating it is wise to keep the slot smaller than one-tenth the frequency of operation of the blade. Hence, that frequency does not 'see' the slot.
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| By combining two elements in this manner, one saves costs in manufacturing and saves real-estate in mounting the antenna. It is noteworthy to mention again that each radiating element must have a different feed structure and most likely a different matching network.
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| == References ==
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| {{reflist}}
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| [[Category:Radio frequency antenna types]]
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