.. názov: RF Fresnel Zone Calculator
.. slimák: rf-fresnel-zone
.. dátum: 26. 12. 2025 15:00:00 UTC
.. tagy: sieť, kalkulačka, nástroj, RF, bezdrôtové
.. kategória: Kalkulačky
.. odkaz:
.. popis: Vypočítajte polomer Fresnelovej zóny pre bezdrôtové RF linky, aby ste zabezpečili správne šírenie signálu
.. typ: text
<style>
    .calc-container {
        max-width: 900px;
        margin: 20px auto;
        padding: 20px;
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</style>
<div class="calc-container">
<div class="calc-header">
<h2>Kalkulačka RF Fresnelovej zóny</h2>
<p>Vypočítajte polomer Fresnelovej zóny pre bezdrôtové RF spojenia. Fresnelova zóna je elipsovitá oblasť okolo vizuálnej viditeľnej dráhy, do ktorej sa šíria rádiové vlny po opustení antény.</p>
<div class="input-grid">
<div class="input-group">
<label for="frequency">Frekvencia:</label>
<div class="input-row">
<input id="frequency" placeholder="Enter frequency" type="text" value="2.4"/>
<select id="freunit">
<option value="ghz">GHz</option>
<option value="mhz">MHz</option>
<option value="khz">kHz</option>
<option value="hz">Hz</option>
</select>
</div>
</div>
<div class="input-group">
<label for="distance">vzdialenosť:</label>
<div class="input-row">
<input id="distance" placeholder="Enter distance" type="text" value="1"/>
<select id="unit">
<option value="feet">Miles</option>
<option value="meters">Kilometre</option>
</select>
</div>
</div>
</div>
<button class="calc-button" onclick="fresnelZone()">Vypočítajte Fresnelovu zónu</button>
</div>
<div class="result-section" id="results">
<div class="section-header">Výsledky výpočtu</div>
<div class="section-content">
<div class="data-row">
<div class="data-label">Polomer Fresnelovej zóny:</div>
<div class="data-value highlight" id="fnr">-</div>
</div>
<div class="data-row">
<div class="data-label">Umiestnenie stredového bodu:</div>
<div class="data-value" id="center">-</div>
</div>
</div>
</div>
<div class="info-box">
<h3>O Fresnelových zónach</h3>
<p>
<strong>Čo je Fresnelova zóna?</strong>Fresnelova zóna je eliptická oblasť okolo viditeľnej dráhy medzi dvoma anténami. Rádiové vlny sa šíria, keď sa pohybujú, a táto zóna predstavuje oblasť, kde tieto vlny môžu konštruktívne alebo deštruktívne interferovať.</p>
<p>
<strong>Prečo je to dôležité?</strong>Pre optimálny výkon RF spojenia by aspoň 60 % prvej Fresnelovej zóny nemalo byť bez prekážok (budovy, stromy, terén). Táto kalkulačka vám pomôže určiť požadovaný polomer vzdialenosti v strede vášho bezdrôtového spojenia.</p>
<p>
<strong>Ako používať:</strong>Zadajte svoju prevádzkovú frekvenciu a celkovú vzdialenosť medzi anténami. Kalkulačka vám ukáže polomer Fresnelovej zóny v jej najširšom bode (stred spojnice).</p>
</div>
</div>
<script>
function fresnelZone() {
    // Set variables from input
    var frequency = Number(document.getElementById("frequency").value);
    var freunit = document.getElementById("freunit").value;
    var distance = Number(document.getElementById("distance").value);
    var unit = document.getElementById("unit").value;

    if (freunit == "ghz") {
        var sf = frequency;
    } else if (freunit == "mhz") {
        var sf = frequency/1000;
    } else if (freunit == "khz") {
        var sf = frequency/1000000;
    } else {
        var sf = frequency/1000000000;
    }


    var d1 = distance / 2;
    var d2 = d1;
    if (unit == "feet") {
        //var radius = Math.round(72.05 * Math.sqrt((d1*d2/(sf))));
        var radius = Math.round(36.03 * Math.sqrt((distance/sf)))
        var distunit = "Miles"
    } else {
        //var radius = Math.round(17.32 * Math.sqrt((d1*d2/(sf))));
        var radius = Math.round(8.657 * Math.sqrt((distance/sf)))
        var distunit = "Kilometers"
    }

    document.getElementById("fnr").textContent = radius + " feet";
    document.getElementById("center").textContent = "Located " + d1 + " " + distunit + " from the first antenna";

    // Show results section
    document.getElementById("results").classList.add("show");

    // Scroll to results
    document.getElementById("results").scrollIntoView({ behavior: 'smooth', block: 'start' });
}

// Add enter key support
document.addEventListener('DOMContentLoaded', function() {
    document.getElementById("frequency").addEventListener('keypress', function(e) {
        if (e.key === 'Enter') {
            fresnelZone();
        }
    });

    document.getElementById("distance").addEventListener('keypress', function(e) {
        if (e.key === 'Enter') {
            fresnelZone();
        }
    });
});
</script>