The HackRF One is an open-source, USB-powered half-duplex software-defined radio transceiver (so it can transmit) operating across a frequency range of 1 MHz to 6 GHz.

The Portapack H2 pairs with a HackRF One and is generally flashed with Mayhem firmware (but there are others). It includes a 2000mAh battery, a 3.5mm audio jack, and a rotary control knob for easy field navigation without needing an external computer. The whole setup is fairly expensive but you get what you pay for - it could hear a leaky microwave on the other side of the country. It also has a low noise amplifier.

RTL-SDR is a realtek very cheap USB based TV tuner which can be used to receive from around 500kHz thru around 1.7GHz. It is pretty deaf to be honest. The windows software HDSDR used with the USB dongle.