8: Find the distance to Lat and Long in KM

I want to find the next things in the vicinity.

I have a radius in KM. For some of the data, there are no correct results for lat and long based on the radius.

        $ lat = 53.2734;
$ long = -7,778320;
$ radius = 5;

$ where = & # 39; ACOS (SIN (field_latitude * 0.0175) & # 39;
, # * SIN (: lat * 0.0175) + COS (field_latitude * 0.0175) & # 39;
, # * COS (: lat * 0.0175) * COS ((: long * 0.0175) - (field length * 0.0175)) & # 39;
, & # 39;) * 6371 <= :radius';

  $query->where ($ wo, [
    ':lat' => $lat,
    ':long' => $long,
    ':radius' => $radius,

$ results = $ query-> execute ();

So I have a query for DB above, but for some lat and long there are no correct results.

Can be output with lat, long calculation based on the radius?

Privacy – Where can I find a very long range WLAN antenna with a range of 50-100 km? Or is it a DIY project?

I want to increase personal safety by getting Wi-Fi connections 50-100 km away from the physical device location with high decibels in milliwatts (dbm) to overcome the dampening of the path through leaves and other obstacles. This would allow me to avoid the geographic restrictions imposed by the local ISP's Wi-Fi connections because I can access the Internet anywhere within the system (within a 100km radius).

I am considering using a Yagi directional antenna or perhaps a parabolic lattice, but the ones I've been able to find so far are limited in their range, at a maximum of 15-20 km, never more than 50 dBm. Where can I find a Yagi or Parabola grid with a range of 50-100 km? Do I have to buy radio devices for industrial applications for this WLAN frequency range or is it a hardware store project? If it is home improvement, what equipment is needed and are there instructions on how to build one?

Do you not know the RF theory at all, but can you increase the WLAN range, for example on a parabola grid of 15 to 20 km to 50 to 100 km?

gm.General Mathematics – What is the force on a steel cable of 100 km / h to a standstill

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