Dual-band plastic waveguide transmission system

Abstract

According to the present disclosure, a dual-band plastic waveguide transmission system is provided. The system may include an RF receiver configured to receive a first signal and a second signal, the first and second signals being transmitted from an RF transmitter at a first carrier frequency and a second carrier frequency higher than the first carrier frequency, respectively; a plastic waveguide device configured to provide a communication channel between the RF transmitter and the RF receiver; and an interconnect device including a first microstrip-to-waveguide transition (MWT) configured to transmit the first signal from the plastic waveguide device to the RF receiver and a second MWT configured to transmit the second signal from the plastic waveguide device to the RF receiver. The frequency bandwidth of the first signal may be adjusted by the plastic waveguide device and the first MWT so that the first signal is received as an upper sideband signal, and the frequency bandwidth of the second signal may be adjusted by the plastic waveguide device and the second MWT so that the second signal is received as a lower sideband signal.

Description

Technical Field

[0001] The present disclosure relates to waveguide links, and more particularly to dual-band plastic waveguide transmission systems.

Background Art

[0002] The demand for greater input / output (I / O) bandwidth in data sensors is increasing due to the explosive growth of network traffic. However, conventional high-speed interconnects face challenges in functional and economic directions. Copper-based electrical links exhibit critical bandwidth limitations caused by skin loss. Optical links require significant capital costs for chip-to-fiber assemblies and E / O (Electrical / Optical) and O / E conversion devices in short-reach high-capacity links.

[0003] As an alternative to solve the problems of conventional high-speed interconnects, recent research has presented that plastic waveguide links, which exhibit inherent low loss and wide-band channel characteristics, can be a promising solution for power / cost-efficient high-speed interconnects. Along with this, there is a need to develop a transmission system that enables ultra-high-speed data transmission through plastic waveguide links.

Summary of the Invention

Problems to be Solved by the Invention

[0004] To solve such problems, an object of the present disclosure is to provide a dual-band plastic waveguide transmission system.

Means for Solving the Problems

[0005] According to one embodiment of the present disclosure, a dual-band plastic waveguide transmission system is provided. The system includes an RF receiver configured to receive a first signal and a second signal transmitted from an RF transmitter at a first carrier frequency and a second carrier frequency higher than the first carrier frequency, respectively; a plastic waveguide device configured to provide a communication channel between the RF transmitter and the RF receiver; and an interconnector including a first microstrip-to-waveguide transition MWT configured to transmit the first signal from the plastic waveguide device to the RF receiver and a second MWT configured to transmit the second signal from the plastic waveguide device to the RF receiver. The frequency bandwidth of the first signal may be adjusted by the plastic waveguide device and the first MWT so that the first signal is received as an upper sideband signal, and the frequency bandwidth of the second signal may be adjusted by the plastic waveguide device and the second MWT so that the second signal is received as a lower sideband signal.

[0006] The system may further include duplexers connected to the first MWT and the second MWT, respectively, for transmitting the first signal and the second signal from the plastic waveguide device.

[0007] Furthermore, the frequency bandwidth of the first signal can be adjusted by adjusting the lower cut-off frequency using the plastic waveguide device, and the frequency bandwidth of the second signal can be adjusted by adjusting the upper cut-off frequency using the plastic waveguide device.

[0008] Furthermore, the plastic waveguide device may include a dielectric tube having a rectangular cross-section. The lower cutoff frequency of the first signal and the upper cutoff frequency of the second signal can be adjusted based on the lateral and longitudinal lengths of the cross-section of the dielectric tube.

[0009] Furthermore, the frequency bandwidth of the first signal can be adjusted by adjusting the upper cutoff frequency using the first MWT, and the frequency bandwidth of the second signal can be adjusted by adjusting the lower cutoff frequency using the second MWT.

[0010] Furthermore, the first MWT and the second MWT may each include a probe element for receiving signals from a feeding line, and a slotted ground plane through which signals radiated from the probe element can be transmitted to the plastic waveguide device.

[0011] Furthermore, the upper cutoff frequency of the first signal may be adjusted based on the length of the probe element of the first MWT and the slot size of the slotted ground plane of the first MWT. The lower cutoff frequency of the second signal may be adjusted based on the length of the probe element of the second MWT and the slot size of the slotted ground plane of the second MWT.

[0012] The RF receiver may be further configured to receive a third signal and a fourth signal transmitted from the RF transmitter at a third carrier frequency lower than the first carrier frequency and a fourth carrier frequency higher than the second carrier frequency, respectively. The interconnecting device may further include a third MWT configured to transmit the third signal from the plastic waveguide device to the RF receiver, and a fourth MWT configured to transmit the fourth signal from the plastic waveguide device to the RF receiver. The frequency bandwidth of the third signal may be adjusted by the plastic waveguide device and the third MWT so that the third signal is received as an upper sideband signal, and the frequency bandwidth of the fourth signal may be adjusted by the plastic waveguide device and the fourth MWT so that the fourth signal is received as a lower sideband signal.

[0013] The system may further include a quadplexer for transmitting the first signal, the second signal, the third signal, and the fourth signal from the plastic waveguide device.

[0014] Furthermore, the frequency bandwidths of the first signal and the third signal can be adjusted by adjusting the lower cutoff frequency using the plastic waveguide device, and the frequency bandwidths of the second signal and the fourth signal can be adjusted by adjusting the upper cutoff frequency using the plastic waveguide device.

[0015] Furthermore, the frequency bandwidth of the first signal can be adjusted by adjusting the upper cutoff frequency with the first MWT, the frequency bandwidth of the second signal can be adjusted by adjusting the lower cutoff frequency with the second MWT, the frequency bandwidth of the third signal can be adjusted by adjusting the upper cutoff frequency with the third MWT, and the frequency bandwidth of the fourth signal can be adjusted by adjusting the lower cutoff frequency with the fourth MWT.

Advantages of the Invention

[0016] According to the present disclosure, a transmission system can be presented that enables ultra-high-speed data transmission by adjusting the frequency bandwidth for single-sideband transmission of dual-band or multi-band RF signals and transmitting and receiving them through a plastic waveguide link.

Brief Description of the Drawings

[0017] [Figure 1] It is an exemplary drawing showing single-sideband transmission.

[0018] [Figure 2] It is an exemplary drawing showing a dual-band plastic waveguide transmission system according to an embodiment of the present disclosure.

[0019] [Figure 3] It is an exemplary drawing showing the lower cut-off frequency and upper cut-off frequency of the plastic waveguide channel response.

[0020] [Figure 4] It is an exemplary drawing showing the configuration of a plastic waveguide device according to an embodiment of the present disclosure.

[0021] [Figure 5] It is an exemplary drawing showing a cross-sectional view of a package substrate including MWT according to an embodiment of the present disclosure.

[0022] [Figure 6a] It is an exemplary drawing showing the slotted ground plane of the A-A' plane in FIG. 5.

[0023] [Figure 6b] It is an exemplary drawing showing the probe element located in the B-B' plane of FIG. 5.

[0024] [Figure 7] This is an illustrative drawing showing a multiband plastic waveguide transmission system according to one embodiment of the contents of this disclosure. [Modes for carrying out the invention]

[0025] Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. First, it should be noted that when assigning reference numerals to the components in each drawing, the same component will be given the same reference numeral whenever possible, even if it is shown in other drawings. Furthermore, in describing the present invention, if it is determined that a specific description of a related known configuration or function may obscure the gist of the present invention, such a detailed description will be omitted.

[0026] Various aspects of the present invention are described below. It should be understood that the invention presented herein can be embodied in various forms, and any particular structure, function, or all thereof presented herein are merely illustrative. A person with ordinary skill in the art to which the present invention belongs will understand that one aspect presented herein can be embodied independently of any other aspect, and that two or more such aspects can be combined in various ways. For example, an apparatus can be embodied or a method can be implemented using any number of aspects described herein. In addition, such an apparatus can be embodied or a method can be implemented using one or more aspects described herein, or other structures, functions, or structures and functions instead of these aspects.

[0027] The radio frequency (RF) communication system described herein can be configured to communicate between an RF transmitter and an RF receiver via a plastic waveguide link exhibiting low-loss and wideband channel characteristics. Such a system can also improve transmission speed by enabling the simultaneous transmission and reception of two or more RF signals in dual-band or multi-band configurations through the plastic waveguide in their respective bandwidths. Furthermore, such a system can implement single-sideband transmission by adjusting the cutoff frequency bandwidth of each RF signal, thereby further improving transmission speed by enabling twice the data rate compared to double-sideband transmission.

[0028] Figure 1 is an illustrative diagram showing single-sideband transmission.

[0029] The present disclosure allows for the application of single-sideband transmission, as illustrated in Figure 1, to achieve twice the data rate compared to double-sideband transmission. In one embodiment, the present disclosure can adjust the slope of the upper cut-off frequency band of the signal, thereby suppressing the upper sideband signal by causing the link frequency characteristics to roll off sharply at the upper cut-off frequency (i.e., to have a high roll-off), and providing the receiver with a transmission signal centered on the lower sideband signal. In another embodiment, the present disclosure can adjust the slope of the lower cut-off frequency band, thereby suppressing the lower sideband signal by causing the link frequency characteristics to roll off sharply at the lower cut-off frequency (i.e., to have a high roll-off), and providing the receiver with a transmission signal centered on the upper sideband signal.

[0030] As described later, this disclosure provides a waveguide link channel that can transmit a larger amount of data while maintaining the power spectrum for each signal by applying the aforementioned single-sideband transmission technique to the low-band (LB) signal and high-band (HB) signal that constitute the dual-band system.

[0031] Figure 2 is an exemplary drawing showing a dual-band plastic waveguide transmission system according to one embodiment of the present disclosure.

[0032] As illustrated in Figure 2, such a system may include an RF transmitter 110, an RF receiver 120, a transmitter-side interconnecting device including microstrip-to-waveguide transitions MWT 140, 141, a receiver-side interconnecting device including MWT 142, 143, duplexers 150, 151, and a bidirectional plastic waveguide (hereinafter referred to as "E-TUBE") device 130.

[0033] The RF transmitter 110 may be configured to transmit a first signal (Data In[0]) and a second signal (Data In[1]) that are upconverted to a first carrier frequency (f1) and a second carrier frequency (f2) higher than the first carrier frequency, respectively. For this purpose, the RF transmitter 110 may include mixers 111, 112 and power amplifiers (PAs) 113, 114 for upconverting the first and second signals to the first and second carrier frequencies, respectively. Although not shown in the separate drawings, the RF transmitter 110 may also include a phase-fixed loop (PLL) for providing a clock signal to the RF transmitter 110, a frequency multiplier for converting the clock signal to the carrier frequency, and so on.

[0034] The RF receiver 120 may be configured to receive first and second signals, which are received at a first carrier frequency and a second carrier frequency, respectively, by downconverting them. The RF receiver 120 may be configured to include appropriate components for receiving signals from the RF transmitter 110. For example, the RF receiver 120 may include low-noise amplifiers (LNAs) 121, 122 and downconverting mixers 123, 124, and may also include a phase sync device, PLL, frequency multiplier, etc., although these are not shown in the separate drawings.

[0035] The E-TUBE device 130 may be configured to provide a communication channel between the RF transmitter 110 and the RF receiver 120. The E-TUBE device 130 may include a plastic (or dielectric) waveguide for signal transmission and reception and metal cladding surrounding it. The metal cladding can confine the radio wave and prevent electromagnetic leakage. In one embodiment, the E-TUBE device 130 may include a plastic waveguide having a rectangular cross-section, but the shape of the waveguide is not limited thereto and may be configured to have a different shape, such as a circular cross-section.

[0036] The transmitting interconnector may be configured to connect the RF transmitter 110 and the E-TUBE device 130 and may include transmitting MWTs 140, 141. The receiving interconnector may be configured to connect the E-TUBE device 130 and the RF receiver 120 and may include receiving MWTs 142, 143. By embodiment, such interconnectors may be embodied in microstrips, strips, coplanar waveguides, etc.

[0037] The first MWT 142 may be configured to transmit a first signal from the E-TUBE device 130 to the RF receiver 120, and the second MWT 143 may be configured to transmit a second signal from the E-TUBE device 130 to the RF receiver 120. The duplexer 151 may be connected to the first MWT 142 and the second MWT 143, respectively, to transmit the first and second signals from the E-TUBE device 130. The duplexer 151 may also be configured to combine or separate the first and second signals and to prevent crosstalk between the first and second signals. Accordingly, a duplexer 150 and MWTs 140, 141 may be provided between the E-TUBE device 130 and the RF transmitter 110.

[0038] The first signal is a low-band (LB) signal 160, whose frequency bandwidth can be adjusted so that it can be received as an upper-sideband signal 162 having a preset bandwidth with reference to the first carrier frequency. The second signal is a high-band (HB) signal 170, whose frequency bandwidth can be adjusted so that it can be received as a lower-sideband signal 172 having a preset bandwidth with reference to the second carrier frequency. For this purpose, as will be described later, the frequency bandwidth of the first signal can be adjusted by the E-TUBE device 130 and the first MWT 140, and the frequency bandwidth of the second signal can be adjusted by the E-TUBE device 130 and the second MWT 141. Through this, the first and second signals, with their bandwidths adjusted, can be received by the RF receiver 120 via the E-TUBE device 130 as single-sideband transmissions, and the RF receiver 120 can receive the first signal 162 and the second signal 172 with their bandwidths adjusted accordingly. In other words, such a system can provide a waveguide link channel that reflects a dual single-sideband transmission scheme.

[0039] For example, the first carrier frequency (f1) may be 115 GHz and the second carrier frequency (f2) may be 170 GHz, and the first and second signals may be adjusted to be transmitted with a bandwidth of ~30 GHz relative to their respective carrier frequencies and received through the E-TUBE device 130. In such a case, the first and second signals may be transmitted together through the plastic waveguide of the E-TUBE device 130 as the upper sideband low band (LB) signal and the lower sideband high band (HB) signal, respectively, in a bandwidth of 115 GHz to 170 GHz, thereby realizing dual-band wideband ultra-high-speed transmission.

[0040] Figure 3 is an exemplary diagram showing the lower and upper cutoff frequencies of the plastic waveguide channel response.

[0041] The frequency bandwidths of the first signal (i.e., the low-band signal) and the second signal (i.e., the high-band signal) can be adjusted by adjusting the lower cutoff frequency and the upper cutoff frequency, respectively. As shown in Figure 2, for the first signal (i.e., the low-band signal) 160, the frequency bandwidth of the first signal can be adjusted by adjusting the lower cutoff frequency using the E-TUBE device 130, and by adjusting the upper cutoff frequency using the first MWT 142. In the same manner, for the second signal (i.e., the high-band signal) 170, the frequency bandwidth of the second signal can be adjusted by adjusting the upper cutoff frequency using the E-TUBE device 130, and also by adjusting the lower cutoff frequency using the second MWT 143.

[0042] Figure 4 is an exemplary drawing showing the configuration of a plastic waveguide device according to one embodiment of the present disclosure.

[0043] As shown in Figure 4, the E-TUBE apparatus 130 may include a plastic waveguide (i.e., dielectric tube) 310 having a rectangular cross-section and metal cladding 320 surrounding the dielectric tube 310. In such a case, the lower cutoff frequency of the first signal and the upper cutoff frequency of the second signal may be adjusted based on the lateral length (b) and longitudinal length (a) of the cross-section of the dielectric tube 310.

[0044] Specifically, the cutoff frequency (fnm) for the dielectric tube illustrated in Figure 4 can be determined by the following formula:

[0045]

number

[0046] Here, c represents the wave velocity of the dielectric tube and can be determined based on the dielectric constant (ε1) and permeability (μ1) of the dielectric tube. a represents the longitudinal length of the dielectric tube, b represents the transverse length of the dielectric tube, and n and m are integers representing the mode coefficients of the wave.

[0047] Figure 5 is an illustrative drawing showing a cross-sectional view of a package substrate including an MWT according to one embodiment of the present disclosure.

[0048] The transmission system relating to this disclosure may be configured to connect a transmitter board and a receiver board via an E-TUBE device 130, and each board may include an IC package. The IC package may include an RF chip (die) 410 and a package substrate 400 on which MWTs 140, 141, 142, and 143 are formed. The IC package may be connected to a printed circuit board (PCB) (not shown) via solder balls 420.

[0049] In one embodiment, the RF chip 410 may be positioned at the lower end of the package substrate 400 and may be attached to the package substrate 400 using bumps 421. In addition, vias 422 may be formed between the RF chip 410 and the package substrate 400, which serve as transmission paths for RF signals.

[0050] MWT140, 141, 142, 143 may include a feeding line 430, a probe element 440, and a slotted ground plane 450. The feeding line 430 can supply RF signals through vias 422 formed between the RF chip 410 and the package substrate 400. The probe element 440 can receive RF signals from the feeding line 430 and radiate them to the slotted ground plane 450. The slotted ground plane 450 can allow the signals radiated from the probe element 440 to pass through and be transmitted to the E-TUBE device 130. MWT140, 141, 142, 143 may be connected to the E-TUBE device 130 via duplexers 150, 151.

[0051] As mentioned above, the first signal (i.e., the low-band signal) may be transmitted to the first MWT 142, and the second signal (i.e., the high-band signal) may be transmitted to the second MWT 143. Here, the probe element 440 and slotted ground plane 450 of each MWT may be used to adjust the frequency bandwidth of the respective signals. Specifically, the upper cutoff frequency of the first signal may be adjusted based on the length of the probe element 440 of the first MWT 142 and the slot size of the slotted ground plane 450 of the first MWT 142. Similarly, the lower cutoff frequency of the second signal may be adjusted based on the length of the probe element 440 of the second MWT 143 and the slot size of the slotted ground plane 450 of the second MWT 143.

[0052] Figure 6a is an exemplary drawing showing the slotted ground plane in the A-A' plane of Figure 5.

[0053] As shown in Figure 6a, slots for low-band signals (LB) and high-band signals (HB) can be formed on the slotted ground plane 450. Here, increasing the lateral lengths 510, 511 of the slots may decrease the cutoff of the corresponding signals, and decreasing the lateral lengths 510, 511 may increase the cutoff of the corresponding signals.

[0054] Figure 6b is an illustrative diagram showing a probe element located in the B-B' plane of Figure 5.

[0055] As shown in Figure 6b, probe elements 440 for low-band signals (LB) and probe elements 440 for high-band signals (HB) can be formed on the B-B' plane of the package substrate 400. Here, increasing the vertical lengths 520 and 521 of the probe elements 440 may decrease the cutoff of the corresponding signal, and decreasing the vertical lengths 520 and 521 may increase the cutoff of the corresponding signal.

[0056] Figure 7 is an exemplary drawing showing a multiband plastic waveguide transmission system according to one embodiment of the present disclosure.

[0057] The plastic waveguide transmission system described herein can be implemented not only as a dual-band transmission system that transmits two RF signals, but also as a multi-band transmission system that can transmit multiple RF signals. The multi-band transmission system can be implemented by adding low-band signals even lower than the dual-band low-band signals and high-band signals even higher than the high-band signals.

[0058] As illustrated in Figure 7, when implemented in a multiband transmission system capable of transmitting four RF signals, the RF receiver 620 may be configured to receive a first signal transmitted from the RF transmitter 610 at a first carrier frequency (f1), a second signal transmitted at a second carrier frequency (f2) higher than the first carrier frequency, a third signal transmitted at a third carrier frequency (f0) lower than the first carrier frequency, and a fourth signal transmitted at a fourth carrier frequency (f3) higher than the second carrier frequency.

[0059] In such a multiband transmission system, the interconnector may include a first MWT 640 configured to transmit a first signal from the E-TUBE device 130 to the RF receiver 620, a second MWT 641 configured to transmit a second signal from the E-TUBE device 130 to the RF receiver 620, a third MWT 642 configured to transmit a third signal from the E-TUBE device 130 to the RF receiver 620, and a fourth MWT 643 configured to transmit a fourth signal from the E-TUBE device 130 to the RF receiver 620.

[0060] The frequency bandwidth of the first signal can be adjusted by the E-TUBE device 130 and the first MWT 640 so that the first signal is received as an upper sideband signal. The frequency bandwidth of the second signal can be adjusted by the E-TUBE device 130 and the second MWT 641 so that the second signal is received as a lower sideband signal. The frequency bandwidth of the third signal can be adjusted by the E-TUBE device 130 and the third MWT 642 so that the third signal is received as an upper sideband signal. The frequency bandwidth of the fourth signal can be adjusted by the E-TUBE device 130 and the fourth MWT 643 so that the fourth signal is received as a lower sideband signal.

[0061] Such a multiband transmission system may include a quadplexer 650 for transmitting the first, second, third, and fourth signals from the E-TUBE device 130.

[0062] Furthermore, the RF transmitter 610 may be configured to include corresponding components for transmitting signals to the RF receiver 620, and a corresponding quadplexer and MWT may be provided between the E-TUBE device 130 and the RF transmitter 610.

[0063] In such cases, the frequency bandwidths of the first signal and the third signal can be adjusted by adjusting the lower cutoff frequency using the E-TUBE device 130, and the frequency bandwidths of the second signal and the fourth signal can be adjusted by adjusting the upper cutoff frequency using the E-TUBE device 130.

[0064] Furthermore, the frequency bandwidth of the first signal can be adjusted by adjusting the upper cutoff frequency using the first MWT640, the frequency bandwidth of the second signal can be adjusted by adjusting the lower cutoff frequency using the second MWT641, the frequency bandwidth of the third signal can be adjusted by adjusting the upper cutoff frequency using the third MWT642, and the frequency bandwidth of the fourth signal can be adjusted by adjusting the lower cutoff frequency using the fourth MWT643.

[0065] The lower and upper cutoff frequencies can be adjusted using the E-TUBE device 130 and MWT 640, 641, 642, and 643 in the same manner as described above in relation to Figures 3 to 6.

[0066] The descriptions of the examples presented are provided so that any person with ordinary skill in the art of the present invention can utilize or practice the invention. Various modifications to such examples are obvious to a person with ordinary skill in the art of the present invention, and the general principles defined herein can be applied to other examples without departing from the scope of the invention. Therefore, the present invention is not limited to the examples presented herein and should be interpreted in the broadest sense consistent with the principles and novel features presented herein.

Claims

1. RF communication system, An RF receiver configured to receive a first signal and a second signal transmitted from an RF transmitter at a first carrier frequency and a second carrier frequency higher than the first carrier frequency, respectively. A plastic waveguide device configured to provide a communication channel between the RF transmitter and the RF receiver and to transmit the first signal and the second signal, The interconnection device includes a first microstrip-to-waveguide transition (MWT) configured to transmit the first signal from the plastic waveguide device to the RF receiver, and a second MWT configured to transmit the second signal from the plastic waveguide device to the RF receiver, The frequency bandwidth of the first signal is adjusted by adjusting the lower cutoff frequency with the plastic waveguide device and adjusting the upper cutoff frequency with the first MWT so that the first signal is received as an upper sideband signal. An RF communication system in which the frequency bandwidth of the second signal is adjusted by adjusting the upper cutoff frequency with the plastic waveguide and adjusting the lower cutoff frequency with the second MWT, such that the second signal is received as a lower sideband signal.

2. The RF communication system according to claim 1, further comprising duplexers connected to the first MWT and the second MWT, respectively, for transmitting the first signal and the second signal from the plastic waveguide device.

3. The plastic waveguide device includes a dielectric tube having a rectangular cross-section, The RF communication system according to claim 1, wherein the lower cutoff frequency of the first signal and the upper cutoff frequency of the second signal are adjusted based on the lateral and longitudinal lengths of the cross-section of the dielectric tube.

4. The first MWT and the second MWT are, A probe element that receives signals from a feeding line; and The RF communication system according to claim 1, further comprising a slotted ground plane through which signals radiated from the probe element are transmitted to the plastic waveguide device.

5. The upper cutoff frequency of the first signal is adjusted based on the length of the probe element of the first MWT and the slot size of the slotted ground plane of the first MWT. The RF communication system according to claim 4, wherein the lower cutoff frequency of the second signal is adjusted based on the length of the probe element of the second MWT and the slot size of the slotted ground plane of the second MWT.

6. The RF receiver is The system is further configured to receive a third signal and a fourth signal transmitted from the RF transmitter at a third carrier frequency lower than the first carrier frequency and a fourth carrier frequency higher than the second carrier frequency, respectively. The aforementioned interconnection device is A third MWT configured to transmit the third signal from the plastic waveguide device to the RF receiver; and The device further includes a fourth MWT configured to transmit the fourth signal from the plastic waveguide device to the RF receiver, The RF communication system according to claim 1, wherein the frequency bandwidth of the third signal is adjusted by the plastic waveguide and the third MWT so that the third signal is received as an upper sideband signal, and the frequency bandwidth of the fourth signal is adjusted by the plastic waveguide and the fourth MWT so that the fourth signal is received as a lower sideband signal.

7. The RF communication system according to claim 6, further comprising a quadplexer for transmitting the first signal, the second signal, the third signal, and the fourth signal from the plastic waveguide device.

8. The RF communication system according to claim 6, wherein the frequency bandwidth of the third signal is adjusted by adjusting the lower cutoff frequency with the plastic waveguide device, and the frequency bandwidth of the fourth signal is adjusted by adjusting the upper cutoff frequency with the plastic waveguide device.

9. The RF communication system according to claim 6, wherein the frequency bandwidth of the third signal is adjusted by adjusting the upper cutoff frequency with the third MWT, and the frequency bandwidth of the fourth signal is adjusted by adjusting the lower cutoff frequency with the fourth MWT.

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