xpath搜索属性时出错

Hello I would like to extract with xpath all items with the name="Frequency" which contains a certain value but it doesn't give me anything. What Am I doing wrong?

XML File:

<products>
    <product>
        <title>PT2400</title>
        <ElectricSpecifications>
           <item name="Frequency">2310 - 2485 MHz (WLAN, BLUETOOTH, ZIGBEE</item>
        </ElectricSpecifications>
    </product>
</products>


foreach ($xpath->query("//product/ElectricSpecifications[@item='Frequency'][contains(., ' $value')]") as $item) {
    var_dump($item);
}

item is not an attribute of ElectricSpecifications, but its child node, so instead of

[@item='Frequency']

syntax, try

item[@name='Frequency']

And so complete XPath should be like

//product/ElectricSpecifications/item[@name='Frequency' and contains(., ' $value')]