$Username="Hugo"
# $Password="abcdefgh"

$ProxyUrl = "http://webproxy:8080"
$WebProxy = [System.Net.WebProxy]::new($ProxyUrl, $true)
$WebClient = [System.Net.Webclient]::new()
$WebClient.Proxy= $webproxy
$WebClient.Proxy.Credentials = Get-Credential $Username

# [System.Net.NetworkCredential]::new($Username, $Password)

# $url="http://aaa.bbb.ccc.ddd/rss.xml"